ASSESSMENT OF DEFICIT SUB-SURFACE DRIP- IRRIGATION AND MULCHING SYSTEMS ON WATER PRODUCTIVITY UNDER TOMATO CROP HELLEN JEROTICH SANG A Research Proposal submitted to the Graduate School in Partial fulfillment for the Requirements of Master of Science Degree in Agricultural Engineering of Egerton University Egerton University August

ASSESSMENT OF DEFICIT SUB-SURFACE DRIP- IRRIGATION AND MULCHING SYSTEMS ON WATER PRODUCTIVITY UNDER TOMATO CROP
HELLEN JEROTICH SANG
A Research Proposal submitted to the Graduate School in Partial fulfillment for the Requirements of Master of Science Degree in Agricultural Engineering of Egerton University

Egerton University
August, 2018

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DECLARATION AND RECOMMENDATIONDECLARATION
I do declare that this is my original work and that it has not been presented before in any other institution for any award.

Signature………………………………………… Date …………………………………
Name:Hellen Jerotich Sang
Reg. No:BM11/11755/16
RECOMMENDATION
This Research proposal has been submitted for examination with our recommendation and approval as University supervisors.

Signature …………………………………. Date ……………………………………..

Dr. Raphael M. Wambua,
Department of Agricultural Engineering
Egerton University
Signature …………………………………. Date ……………………………………..

Dr. (Eng). James M. Raude,Soil, Water & Environmental Engineering Department,Jomo Kenyatta University of Agriculture & Technology

ABSTRACTThe great challenge of the agricultural sector is to produce more food from less water. The problem facing tomato growers in Njoro Sub County is to optimize fruit quality and yield through water management. This requires maximizing yield per unit of water consumed. However, it is unclear which water management strategy, or deficit irrigation, would maximize yield and quality of fruit using drip irrigation. The objective of this study is to assess the effect of deficit drip – irrigation and mulching systems on water productivity of tomato (Lycopersicon esculentum mill) in Njoro sub county. The study will be carried out on experimental plots of 4m2 in a shade at Egerton University, Njoro campus using factorial experimental design with twelve treatments and three replications. The estimated crop water requirement will be applied to the respective plots based on the various irrigation levels and the agronomic parameters and yield measurements taken on weekly basis. The tomato water productivity under deficit drip – irrigation and mulching practices for the sub county will then be evaluated from the water use efficiency. Climatic data will be obtained from the weather station while the soil and crop parameters will be determined during the study in the experimental field as input to the AQUA Crop model to simulate the tomato water requirement to test its applicability to estimate the crop water requirements. The optimal and economical tomato water requirement will be obtained for application to ensure high production with less water. This will benefit farmers by enabling them to produce more with available less water and by extension poverty reduction by improving the agri-business of the small scale farmers in the sub county.

TABLE OF CONTENTS TOC o “1-3” h z u DECLARATION AND RECOMMENDATION PAGEREF _Toc520974914 h iiABSTRACT PAGEREF _Toc520974915 h iiiTABLE OF CONTENTS PAGEREF _Toc520974916 h ivLIST OF FIGURES PAGEREF _Toc520974917 h viiLIST OF TABLES PAGEREF _Toc520974918 h viiiLIST OF APPENDICES PAGEREF _Toc520974919 h ixLIST OF SYMBOLS AND ABBREVIATIONS PAGEREF _Toc520974920 h xCHAPTER ONE PAGEREF _Toc520974921 h 1INTRODUCTION PAGEREF _Toc520974922 h 11.1Background PAGEREF _Toc520974923 h 11.2Statement of the Problem PAGEREF _Toc520974924 h 21.3 Objectives PAGEREF _Toc520974925 h 21.3.1 Main Objective PAGEREF _Toc520974926 h 21.3.2 Specific Objectives PAGEREF _Toc520974927 h 31.4 Research Questions PAGEREF _Toc520974928 h 31.5 Justification PAGEREF _Toc520974929 h 31.6 Scope PAGEREF _Toc520974930 h 4CHAPTER TWO PAGEREF _Toc520974931 h 5LITERATURE REVIEW PAGEREF _Toc520974932 h 52.1 Overview of Water Saving and Irrigation PAGEREF _Toc520974933 h 52.1.1 Irrigation PAGEREF _Toc520974934 h 52.2 Climate Change and the Impacts PAGEREF _Toc520974935 h 62.2.1 Climate Change Impact on Environmental Resources PAGEREF _Toc520974936 h 72.2.2 Climate Change Impacts on Population Growth PAGEREF _Toc520974937 h 72.2.3 Climate Change Impact on Water Use efficiency PAGEREF _Toc520974938 h 72.3 Water Saving Irrigation Strategies PAGEREF _Toc520974939 h 82.3.1 Deficit irrigation PAGEREF _Toc520974940 h 82.3.2 Mulching PAGEREF _Toc520974941 h 92.4 Strategies for Improving Vegetable Farming Productivity PAGEREF _Toc520974942 h 102.5 Interactive Impacts of Deficit Irrigation and Mulching PAGEREF _Toc520974943 h 112.6 Vegetables PAGEREF _Toc520974944 h 122.7 Reference evapotranspiration ETO Estimation Methods PAGEREF _Toc520974945 h 122.7.1 Penman–Monteith method PAGEREF _Toc520974946 h 122.7.2 Blaney-Criddle Method PAGEREF _Toc520974947 h 132.7.3 Hargreaves Method PAGEREF _Toc520974948 h 132.8 Crop Water Requirement Simulation Models PAGEREF _Toc520974949 h 152.8.1 CROPWAT model PAGEREF _Toc520974950 h 152.8.2 AQUA Crop Model PAGEREF _Toc520974951 h 15CHAPTER THREE PAGEREF _Toc520974952 h 17MATERIALS AND METHODS PAGEREF _Toc520974953 h 173.1 Description of Study Area PAGEREF _Toc520974954 h 173.1.1 Location of Study Area PAGEREF _Toc520974955 h 173.1.2 Climatic conditions PAGEREF _Toc520974956 h 173.1.3 Soil Conditions PAGEREF _Toc520974957 h 183.1.4 Experimental Set up and Data Acquisition PAGEREF _Toc520974958 h 183.1.5 Land preparation, Seedbed preparation and transplanting PAGEREF _Toc520974959 h 193.1.6 Drip Irrigation System Layout PAGEREF _Toc520974960 h 203.2 Estimation of Tomato Crop Water Requirement PAGEREF _Toc520974961 h 203.2.1 Estimation of Reference Evapotranspiration (ETo) PAGEREF _Toc520974962 h 213.2.2 Estimation of Crop Coefficient PAGEREF _Toc520974963 h 213.3 Determination of Tomato Water Productivity PAGEREF _Toc520974964 h 213.3.1 Water Use Efficiency PAGEREF _Toc520974965 h 213.3.2 Crop Coefficient (kc) PAGEREF _Toc520974966 h 223.3.3 Irrigation Water Requirement PAGEREF _Toc520974967 h 233.4 Estimating the Crop Water Requirement of Tomato using AQUA Crop Model for the Njoro Sub County PAGEREF _Toc520974968 h 233.4.1 Soil Data PAGEREF _Toc520974969 h 243.4.2 Climatic data PAGEREF _Toc520974970 h 253.4.3 Crop Parameters PAGEREF _Toc520974971 h 253.5 Statistical Analysis PAGEREF _Toc520974972 h 263.5.1 Root Mean Square Error (RMSE) PAGEREF _Toc520974973 h 263.5.2 Nash and Sutcliffe Efficiency PAGEREF _Toc520974974 h 263.6 Expected Results PAGEREF _Toc520974975 h 274.0 WORK PLAN PAGEREF _Toc520974976 h 285.0 BUDGET PAGEREF _Toc520974977 h 29REFERENCES PAGEREF _Toc520974978 h 30APPENDICES PAGEREF _Toc520974979 h 33

LIST OF FIGURES TOC h z c “Figure 3.” Figure 3. 1 : Location of Njoro Sub County PAGEREF _Toc522193015 h 19Figure 3. 2 : Experimental plots layout PAGEREF _Toc522193016 h 21

LIST OF TABLES TOC h z c “Table 3.” Table 3. 1: Treatments and water levels PAGEREF _Toc522193017 h 21Table 3. 2: The Aqua Crop model input data and model output PAGEREF _Toc522193018 h 26
LIST OF APPENDICES TOC h z c “Table 1.” Table 1. 1 Mean daily percentage (p) of annual day time hours for different latitudes PAGEREF _Toc522193019 h 37Table 1. 2 Crop coefficients for specific crops PAGEREF _Toc522193020 h 38
LIST OF SYMBOLS AND ABBREVIATIONSSymbol Description
CB Cost Benefit
CPE Cumulative Pan Evaporation
CWR Crop Water Requirement
DI Deficit Irrigation
ETa Actual Evapotranspiration
ETc Crop Evapotranspiration
ETo Reference Evapotranspiration
IWR Irrigation Water Requirement
Kc Crop Coefficient
MC Moisture Content
PWP Permanent Wilting Point
TAW Total Available water
WP Water Productivity
WUE Water Use Efficiency
Kg Kilogram

CHAPTER ONEINTRODUCTIONBackgroundTomato is one of the most widely grown vegetables in the world. In many parts of the world, tomato is produced under irrigation. However, due to the global expansion of irrigated areas and the limited availability of irrigation water due to weather changes and competition for fresh water resources, there is need to optimize water use in order to maximize crop yields under water deficit conditions. Agronomic measures such as varying tillage practices, mulching and use of anti-transpirants can increase water productivity. Another option is deficit irrigation, which is a process of exposing the plant to a certain level of water stress during a particular growing period, or throughout the whole growing season, without significant reduction in yield ADDIN EN.CITE <EndNote><Cite><Author>Birhanu</Author><Year>2010</Year><RecNum>59</RecNum><DisplayText>(Birhanu and Tilahun, 2010)</DisplayText><record><rec-number>59</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>59</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Birhanu, K</author><author>Tilahun, Ketema</author></authors></contributors><titles><title>Fruit yield and quality of drip-irrigated tomato under deficit irrigation</title><secondary-title>African Journal of Food, Agriculture, Nutrition and Development</secondary-title></titles><periodical><full-title>African Journal of Food, Agriculture, Nutrition and Development</full-title></periodical><volume>10</volume><number>2</number><dates><year>2010</year></dates><isbn>1684-5374</isbn><urls></urls></record></Cite></EndNote>(Birhanu and Tilahun, 2010).

Drip irrigation in combination with mulch is an appropriate system, which can significantly improve the crop water productivity. Surface mulch has been used to improve soil water retention, reduction of soil temperature and reduction of wind velocity at the soil surface on agricultural land. For commercial production of vegetable crops in many regions of the world, the use of mulch has become an important cultural practice to maximize water use efficiency by the plant and to improve the growth. When mulch is placed over the soil surface, a favourable soil-water-plant relation is created ADDIN EN.CITE <EndNote><Cite><Author>Singh</Author><Year>2016</Year><RecNum>57</RecNum><DisplayText>(Singh, 2016)</DisplayText><record><rec-number>57</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>57</key></foreign-keys><ref-type name=”Thesis”>32</ref-type><contributors><authors><author>Singh, Davinder</author></authors></contributors><titles><title>Growth, yield and quality of chilli (Capsicum annuum L.) in relation to use of various types of mulches</title></titles><dates><year>2016</year></dates><publisher>Punjab Agricultural University, Ludhiana</publisher><urls></urls></record></Cite></EndNote>(Singh, 2016).

It is very critical to make efficient use of water and bring more area under irrigation through available water resources. This can be achieved by introducing advanced methods of irrigation and improved water management practices. The possibility of applying water at very slow rates offers drip irrigation system the means to deliver water to the soil in small and frequent quantities at a relatively low cost compared to other pressurized systems such as sprinkler irrigation ADDIN EN.CITE <EndNote><Cite><Author>Amare</Author><Year>2017</Year><RecNum>60</RecNum><DisplayText>(Amare<style face=”italic”> et al.</style>, 2017)</DisplayText><record><rec-number>60</rec-number><foreign-keys><key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″>60</key></foreign-keys><ref-type name=”Thesis”>32</ref-type><contributors><authors><author>Amare, Haileslassie</author><author>Asfaw, Kebede</author><author>Kassahun, Alebachew</author></authors></contributors><titles><title>Evaluation of Deficit Irrigation and Mulching on Water Productivity of Tomato (Lycopersicon esculentum Mill) Under Drip Irrigation System at Kallu Woreda, South Wollo, Ethiopia</title></titles><dates><year>2017</year></dates><publisher>Harmaya University</publisher><urls></urls></record></Cite></EndNote>(Amare et al., 2017).

Correct irrigation frequency can provide optimum growing conditions to the crop and minimize over use of water. Use of organic, or inorganic, mulch may improve crop yield by conserving soil water ADDIN EN.CITE <EndNote><Cite><Author>Mukherjee</Author><Year>2018</Year><RecNum>58</RecNum><DisplayText>(Mukherjee<style face=”italic”> et al.</style>, 2018)</DisplayText><record><rec-number>58</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>58</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Mukherjee, Asis</author><author>Sarkar, S</author><author>Sarkar, A</author></authors></contributors><titles><title>Productivity and Profitability of Tomato Due to Irrigation Frequency and Mulch</title><secondary-title>International Journal of Vegetable Science</secondary-title></titles><periodical><full-title>International Journal of Vegetable Science</full-title></periodical><pages>43-57</pages><volume>24</volume><number>1</number><dates><year>2018</year></dates><isbn>1931-5260</isbn><urls></urls></record></Cite></EndNote>(Mukherjee et al., 2018). In Nakuru-North Sub County, tomato is one of the major vegetable crops, in terms of acreage. The crop is largely grown in the open-field and is mainly rain-fed. The vulnerability of tomatoes to weather conditions has several consequences. For instance low crop production, high food demand and consequently high food prices. In the same vein, unfavorable weather may lead to reduced farm returns. With changing weather conditions, greenhouse tomato production is likely to become more popular as it provides protection against unfavorable weather conditions ADDIN EN.CITE <EndNote><Cite><Author>Wachira</Author><Year>2012</Year><RecNum>61</RecNum><DisplayText>(Wachira, 2012)</DisplayText><record><rec-number>61</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>61</key></foreign-keys><ref-type name=”Thesis”>32</ref-type><contributors><authors><author>Wachira, John Mwangi</author></authors></contributors><titles><title>Comparative analysis of greenhouse versus open-field small-scale tomato production in Nakuru-North District, Kenya</title></titles><dates><year>2012</year></dates><urls></urls></record></Cite></EndNote>(Wachira, 2012).

Statement of the ProblemThere is water scarcity for agricultural production in Njoro Sub County in the months of March and December due to competition for water resources due to the rapid growth of population, industrialization and urbanization The goal therefore, is to determine the optimum tomato water requirement to increase productivity, which is to produce high yields from less water under good management practices. Unfortunately, the challenge facing tomato growers in Njoro Sub County is to optimize fruit quality and yield through water management since it is unclear which water management strategy, or deficit irrigation, would maximize yield and quality of fruit using drip irrigation. Limited research has been conducted to study the effect of deficit drip – irrigation in combination with mulching on the agricultural land. Water, inspite of being a limiting factor for agricultural production, irrigation with water deficit index provides greater economic return than total irrigation. Deficit irrigation management is possible when crop production function is estimated. When properly applied, the technique shows great potential to increase water use efficiency, especially in areas of low water availability ADDIN EN.CITE <EndNote><Cite><Author>Monte</Author><Year>2013</Year><RecNum>101</RecNum><DisplayText>(Monte<style face=”italic”> et al.</style>, 2013)</DisplayText><record><rec-number>101</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>101</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Monte, José A</author><author>Carvalho, Daniel F de</author><author>Medici, Leonardo O</author><author>da Silva, Leonardo DB</author><author>Pimentel, Carlos</author></authors></contributors><titles><title>Growth analysis and yield of tomato crop under different irrigation depths</title><secondary-title>Revista Brasileira de Engenharia Agrícola e Ambiental</secondary-title></titles><periodical><full-title>Revista Brasileira de Engenharia Agrícola e Ambiental</full-title></periodical><pages>926-931</pages><volume>17</volume><number>9</number><dates><year>2013</year></dates><isbn>1415-4366</isbn><urls></urls></record></Cite></EndNote>(Monte et al., 2013). This study will therefore work to improve the agro-business management by determining the optimal tomato water requirement that results to increased water productivity.

1.3 Objectives 1.3.1 Main ObjectiveThe main objective of this study is to evaluate the effects of deficit drip – irrigation and mulching systems on tomato water productivity in Njoro Sub County, Nakuru County.

1.3.2 Specific ObjectivesThe specific objectives of this study are to:
Estimate crop water requirement for tomato using both Blaney – Criddle and Hargreaves methods for Njoro Sub County.

Determine the interactive effect of deficit drip – irrigation and mulching on water use efficiency (WUE) for different growth stages of tomato production in the sub county.

Determine tomato water productivity under different scenarios (deficit drip – irrigation and mulching systems) using AQUA Crop model in the sub county.

Optimize irrigation relative to water delivery and application schemes under different water management regimes (densities).

1.4 Research QuestionsHow is the distribution of tomato crop water requirement using Blaney – Criddle and Hargreaves methods respectively in Njoro Sub County?
How does the interactive impact of deficit drip – irrigation and mulching affect water use efficiency for different stages of tomato production in the sub county?
How is the tomato water productivity under different scenarios (deficit drip – irrigation and grass mulch) using AQUA Crop model for the sub county?
How is the optimization of irrigation relative to water delivery and application schemes under different water management regimes (densities)?
1.5 JustificationWhen water supplies are limiting, the farmer’s goal should be to maximize net income per unit water used rather than per land unit. Recently, emphasis has been placed on the concept of water productivity (WP), defined either as the yield or net income per unit of water used in ET. WP increases under Deficit Irrigation (DI), relative to its value under full irrigation, as shown experimentally for many crops ADDIN EN.CITE ;EndNote;;Cite;;Author;Fereres;/Author;;Year;2006;/Year;;RecNum;62;/RecNum;;DisplayText;(Fereres and Soriano, 2006);/DisplayText;;record;;rec-number;62;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;62;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Fereres, Elias;/author;;author;Soriano, María Auxiliadora;/author;;/authors;;/contributors;;titles;;title;Deficit irrigation for reducing agricultural water use;/title;;secondary-title;Journal of experimental botany;/secondary-title;;/titles;;periodical;;full-title;Journal of experimental botany;/full-title;;/periodical;;pages;147-159;/pages;;volume;58;/volume;;number;2;/number;;dates;;year;2006;/year;;/dates;;isbn;1460-2431;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Fereres and Soriano, 2006).

Deficit irrigation scheduling is one way of maximizing water use efficiency for higher yields per unit of irrigation water applied; the crop is exposed to a certain level of water stress either during a particular period or throughout the whole growing period. The expectation is that any yield reduction resulting from the water stress will be insignificant compared with the benefits gained through diverting the saved water to irrigate other crops. Crop varieties most suitable for deficit irrigation are those with a short growing season and are tolerant to drought. In implementing deficit irrigation, consideration must be given to soil retention capacity, as well as, modification of agronomic practices like plant population, date of planting and fertilizer application. Tomato plants are sensitive to water stress and show high correlation between evapo-transpiration and crop yield ADDIN EN.CITE ;EndNote;;Cite;;Author;Ramalan;/Author;;Year;2010;/Year;;RecNum;63;/RecNum;;DisplayText;(Ramalan;style face=”italic”; et al.;/style;, 2010);/DisplayText;;record;;rec-number;63;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;63;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Ramalan, AA;/author;;author;Nega, H;/author;;author;Oyebode, MA;/author;;/authors;;/contributors;;titles;;title;Effect of deficit irrigation and mulch on water use and yield of drip irrigated onions;/title;;secondary-title;WIT Transactions on Ecology and the Environment;/secondary-title;;/titles;;periodical;;full-title;WIT Transactions on Ecology and the Environment;/full-title;;/periodical;;pages;39-50;/pages;;volume;134;/volume;;dates;;year;2010;/year;;/dates;;isbn;1845644468;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Ramalan et al., 2010). Studies reveal that drip irrigation with mulch has an explicit role in increasing the yield and water productivity of tomato ADDIN EN.CITE ;EndNote;;Cite;;Author;Amare;/Author;;Year;2017;/Year;;RecNum;60;/RecNum;;DisplayText;(Amare;style face=”italic”; et al.;/style;, 2017);/DisplayText;;record;;rec-number;60;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;60;/key;;/foreign-keys;;ref-type name=”Thesis”;32;/ref-type;;contributors;;authors;;author;Amare, Haileslassie;/author;;author;Asfaw, Kebede;/author;;author;Kassahun, Alebachew;/author;;/authors;;/contributors;;titles;;title;Evaluation of Deficit Irrigation and Mulching on Water Productivity of Tomato (Lycopersicon esculentum Mill) Under Drip Irrigation System at Kallu Woreda, South Wollo, Ethiopia;/title;;/titles;;dates;;year;2017;/year;;/dates;;publisher;Harmaya University;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Amare et al., 2017). Grass mulch will be used for the study since it is cheap and readily available ADDIN EN.CITE ;EndNote;;Cite;;Author;Kere;/Author;;Year;2003;/Year;;RecNum;70;/RecNum;;DisplayText;(Kere;style face=”italic”; et al.;/style;, 2003);/DisplayText;;record;;rec-number;70;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;70;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Kere, GM;/author;;author;Nyanjage, MO;/author;;author;Liu, G;/author;;author;Nyalala, SPO;/author;;/authors;;/contributors;;titles;;title;Influence of drip irrigation schedule and mulching materials on yield and quality of greenhouse tomato (Lycopersicon esculentum Mill.’Money Maker’);/title;;secondary-title;Asian Journal of Plant Sciences;/secondary-title;;/titles;;periodical;;full-title;Asian Journal of Plant Sciences;/full-title;;/periodical;;pages;1052-1058;/pages;;volume;2;/volume;;number;14;/number;;dates;;year;2003;/year;;/dates;;isbn;1682-3974;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Kere et al., 2003).

1.6 Scope and limitations
Tomato crop water requirements will be investigated in a shade and therefore the impact of possible climate variation will not be taken into consideration during the study. Climatic factors will only be considered for simulations and calibrations of the AQUA Crop model. There are many management practices that tend to increase water productivity. This study will focus on the use of grass mulch of different densities and application of different drip irrigation levels. The study will be carried out through experimental plots in a shelter at Egerton University, Njoro. Soil analysis from the site will be done to determine moisture content, texture, field capacity, bulk density and permanent wilting point. The secondary data that will be required for crop water requirement simulation using AQUA Crop model will be rainfall, sunshine hours, minimum and maximum air temperature, wind speed and relative humidity.

The study will only assess the impact of deficit drip irrigation and mulching while the impact of pest and disease investment will not be accounted for but measures to remedy them will be taken into consideration.

CHAPTER TWOLITERATURE REVIEW2.1 Overview of Water Saving and IrrigationIrrigation management and water saving involves controlling crop water use which is a function of reference crop evapotranspiration (ETo), soil water extraction, soil evaporation, soil water balance and the rooting depth. Water saving strategies in agriculture include; irrigation type, capturing and storing water, drought-tolerant crops, dry farming, compost, cover crops and conservation tillage ADDIN EN.CITE ;EndNote;;Cite;;Author;Molden;/Author;;Year;2010;/Year;;RecNum;56;/RecNum;;DisplayText;(Molden;style face=”italic”; et al.;/style;, 2010);/DisplayText;;record;;rec-number;56;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;56;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Molden, David;/author;;author;Oweis, Theib;/author;;author;Steduto, Pasquale;/author;;author;Bindraban, Prem;/author;;author;Hanjra, Munir A;/author;;author;Kijne, Jacob;/author;;/authors;;/contributors;;titles;;title;Improving agricultural water productivity: Between optimism and caution;/title;;secondary-title;Agricultural Water Management;/secondary-title;;/titles;;periodical;;full-title;Agricultural Water Management;/full-title;;/periodical;;pages;528-535;/pages;;volume;97;/volume;;number;4;/number;;dates;;year;2010;/year;;/dates;;isbn;0378-3774;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Molden et al., 2010).
2.1.1 IrrigationIrrigation is a process of providing controlled amounts of water to plants, agricultural crops, orchards and landscapes at required intervals. An irrigation system is a system applying water to land by means of artificial canals, ditches, and pipes, especially to promote the growth of food crops. The irrigation water is conveyed and delivered to the crop through various water distribution methods. The common distribution methods include; sprinkler irrigation, surface irrigation (basin, flooding, and furrow), sub-surface irrigation and drip irrigation ADDIN EN.CITE ;EndNote;;Cite;;Author;Orang;/Author;;Year;2008;/Year;;RecNum;57;/RecNum;;DisplayText;(Orang;style face=”italic”; et al.;/style;, 2008);/DisplayText;;record;;rec-number;57;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;57;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Orang, Morteza N;/author;;author;Scott Matyac, J;/author;;author;Snyder, Richard L;/author;;/authors;;/contributors;;titles;;title;Survey of irrigation methods in California in 2001;/title;;secondary-title;Journal of Irrigation and Drainage Engineering;/secondary-title;;/titles;;periodical;;full-title;Journal of Irrigation and Drainage Engineering;/full-title;;/periodical;;pages;96-100;/pages;;volume;134;/volume;;number;1;/number;;dates;;year;2008;/year;;/dates;;isbn;0733-9437;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Orang et al., 2008). The methods are discussed as follows;
2.1.2 Sprinkler Irrigation
Sprinkler water distribution method is a method of applying irrigation water in way that it mimics natural rainfall. Water is distributed through a system of pipes usually by pumping, then sprayed into the air through sprinklers so that it breaks up into small water drops which fall to the ground ADDIN EN.CITE ;EndNote;;Cite;;Author;Ahaneku;/Author;;Year;2010;/Year;;RecNum;106;/RecNum;;DisplayText;(Ahaneku, 2010);/DisplayText;;record;;rec-number;106;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;106;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Ahaneku, Isiguzo E;/author;;/authors;;/contributors;;titles;;title;Performance evaluation of portable sprinkler irrigation system in Ilorin, Nigeria;/title;;secondary-title;Indian Journal of Science and Technology;/secondary-title;;/titles;;periodical;;full-title;Indian Journal of Science and Technology;/full-title;;/periodical;;pages;853-857;/pages;;volume;3;/volume;;number;8;/number;;dates;;year;2010;/year;;/dates;;isbn;0974-5645;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Ahaneku, 2010). Sprinkler distribution method has a layout of the mainline, submainline, laterals and nozzles as shown in Plate 2.1.

Sprinkler distribution method has high initial cost, loss of water due to evaporation from the area during irrigation and its field application efficiency of 75% is lower, hence will not be used in this study.

2.1.3 Surface Irrigation
Basin Irrigation
Basin water distribution method is the most used irrigation method in the world. This irrigation method is used mostly for rice and other crops and also orchard tree crops. In the basin irrigation system water surface is levelled in the basins. In the basins there are perimeter dams which allow the infiltration after the cut off and prevent the runoff ADDIN EN.CITE ;EndNote;;Cite;;Author;Hakala;/Author;;Year;2008;/Year;;RecNum;102;/RecNum;;DisplayText;(Hakala and Pekonen, 2008);/DisplayText;;record;;rec-number;102;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;102;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Hakala, Anne;/author;;author;Pekonen, Liisa;/author;;/authors;;/contributors;;titles;;title;The Impact of the Irrigation System and Agricultural Production on Water Quality in Chókwé;/title;;/titles;;dates;;year;2008;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Hakala and Pekonen, 2008). Basin distribution method has erosion risks, wastage of water due to evaporation and percolation and a lower application efficiency of 60%, hence it will not be used in this study.

Furrow irrigation
Furrow water distribution method is one of the surface irrigation methods in which small regular channels direct water across the field. Furrow irrigation method is best suited to deep, moderately permeable soils with uniform flat or gentle slope of 0.1-0.5% for crops that are cultivated in rows such as vegetables, maize, cotton, tomato and potatoes ADDIN EN.CITE ;EndNote;;Cite;;Author;Teklu;/Author;;Year;2016;/Year;;RecNum;108;/RecNum;;DisplayText;(Teklu, 2016);/DisplayText;;record;;rec-number;108;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;108;/key;;/foreign-keys;;ref-type name=”Thesis”;32;/ref-type;;contributors;;authors;;author;Teklu, L;/author;;/authors;;/contributors;;titles;;title;Effect of Furrow Irrigation Methods Under Deficit Irrigation on Growth, Yield and Water Productivity of Tomato (Solanum Lycopersicum L.) at Dugda District, East Shewa Zone, Eastern Oromia, Ethiopia;/title;;/titles;;dates;;year;2016;/year;;/dates;;publisher;Haramaya University;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Teklu, 2016). Furrow distribution method consists of an inlet, furrows (holding water), bunds and an outlet ADDIN EN.CITE ;EndNote;;Cite;;Author;Akay;/Author;;Year;2015;/Year;;RecNum;109;/RecNum;;DisplayText;(Akay, 2015);/DisplayText;;record;;rec-number;109;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;109;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Akay, Ufuk;/author;;/authors;;/contributors;;titles;;title;Optimization of a tool for the choice of an irrigation system based on local parameters;/title;;/titles;;dates;;year;2015;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Akay, 2015) as shown in Plate 2.2. In Furrow distribution method, there is wastage of water and dependency on soil slope. The method also has a lower field application efficiency of 60% and hence will not be used in this study.

2.1.4 Drip irrigation system
In drip irrigation water distribution, also called trickle irrigation or localized irrigation, the water is led to the field through a pipe system. On the field, next to the row of plants or trees, a tube is installed. At regular intervals, near the plants or trees, a hole is made in the tube and equipped with an emitter. The water is supplied slowly, drop by drop, to the plants through the emitters ADDIN EN.CITE ;EndNote;;Cite;;Author;BAMOHUNI;/Author;;Year;2011;/Year;;RecNum;105;/RecNum;;DisplayText;(Bamohuni, 2011);/DisplayText;;record;;rec-number;105;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;105;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Bamohuni, S;/author;;/authors;;/contributors;;titles;;title;Design proposal of drip irrigation system for an efficient management of irrigation water for maize improved seeds production in a part of seeds farm of loumbila;/title;;secondary-title;Universita degli Studi di Firenze Facolta di Agraria;/secondary-title;;/titles;;periodical;;full-title;Universita degli Studi di Firenze Facolta di Agraria;/full-title;;/periodical;;pages;33-40;/pages;;dates;;year;2011;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Bamohuni, 2011). A drip distribution method layout consist of a source, mainline, sub mainline, laterals and emitters ADDIN EN.CITE ;EndNote;;Cite;;Author;Keshtgar;/Author;;Year;2012;/Year;;RecNum;107;/RecNum;;DisplayText;(Keshtgar, 2012);/DisplayText;;record;;rec-number;107;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;107;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Keshtgar, Amir;/author;;/authors;;/contributors;;titles;;title;Optimum design of drip irrigation system using microtubes as emitters;/title;;/titles;;dates;;year;2012;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Keshtgar, 2012) as shown in Plate 2.3.

Drip distribution method has little water loss due to evaporation or runoff and is good for mulched areas because it can directly soak the soil without washing away the mulch. Drip irrigation applies water only to the point of interest and thus has a high application efficiency of 90% with less labour cost, hence the method will be used in this study.

2.2 Climate Change and the Impacts
Climate change refers to seasonal changes over a long period with respect to the growing accumulation of greenhouse gases in the atmosphere. Climate change can impact on; environmental resources, population growth, water use efficiency, hydrology, agriculture and water resources.

2.2.1 Climate Change Impact on Environmental ResourcesThe possible impacts of climate change and environmental variability are already evident in most parts of the world that is realizing increased temperature rates and prolonged flood or drought conditions that alter agricultural activities and livelihoods. More erratic rainfall patterns and unpredictable high temperature spells will consequently reduce crop productivity ADDIN EN.CITE ;EndNote;;Cite;;Author;Mngumi;/Author;;Year;2016;/Year;;RecNum;118;/RecNum;;DisplayText;(Mngumi, 2016);/DisplayText;;record;;rec-number;118;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;118;/key;;/foreign-keys;;ref-type name=”Thesis”;32;/ref-type;;contributors;;authors;;author;Mngumi, Julius W;/author;;/authors;;/contributors;;titles;;title;Perceptions of climate change, environmental variability and the role of agricultural adaptation strategies by small-scale farmers in Africa: the case of Mwanga district in Northern Tanzania;/title;;/titles;;dates;;year;2016;/year;;/dates;;publisher;University of Glasgow;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Mngumi, 2016).

The future water resources will be increasingly stressed by climate change causing the gap between water supply and demand for water to expand. With warmer weather, water demand is expected to increase while water supply is expected to decrease. Agricultural consumption, which is the major user for water supply, will be increased due to both decreasing precipitation and increasing evapotranspiration ADDIN EN.CITE ;EndNote;;Cite;;Author;Nasr Azadani;/Author;;Year;2012;/Year;;RecNum;120;/RecNum;;DisplayText;(Nasr Azadani, 2012);/DisplayText;;record;;rec-number;120;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;120;/key;;/foreign-keys;;ref-type name=”Thesis”;32;/ref-type;;contributors;;authors;;author;Nasr Azadani, Fariborz;/author;;/authors;;/contributors;;titles;;title;Modeling the impact of climate change on water resources case study: Arkansas River Basin in Colorado;/title;;/titles;;dates;;year;2012;/year;;/dates;;publisher;Colorado State University. Libraries;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Nasr Azadani, 2012).

2.2.2 Climate Change Impacts on Population GrowthBecause of climate change the economic cost is likely to be increased and the overall crop yield may decline, increasing the risk of poverty and hunger and hence declination in the population growth ADDIN EN.CITE ;EndNote;;Cite;;Author;Abbaspour;/Author;;Year;2009;/Year;;RecNum;119;/RecNum;;DisplayText;(Abbaspour;style face=”italic”; et al.;/style;, 2009);/DisplayText;;record;;rec-number;119;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;119;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Abbaspour, Karim C;/author;;author;Faramarzi, Monireh;/author;;author;Ghasemi, Samaneh Seyed;/author;;author;Yang, Hong;/author;;/authors;;/contributors;;titles;;title;Assessing the impact of climate change on water resources in Iran;/title;;secondary-title;Water resources research;/secondary-title;;/titles;;periodical;;full-title;Water resources research;/full-title;;/periodical;;volume;45;/volume;;number;10;/number;;dates;;year;2009;/year;;/dates;;isbn;1944-7973;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Abbaspour et al., 2009).

2.2.3 Climate Change Impact on Water Use efficiencyHuman activity is leading to increase in greenhouse gas concentrations, which leads to changes in climate. Irrigation water requirements vary according to the balance between precipitation and evapotranspiration and hence fluctuations in soil moisture status. Global warming influences temperature and rainfall patterns, thus leading to direct impacts on soil moisture ADDIN EN.CITE ;EndNote;;Cite;;Author;De Silva;/Author;;Year;2007;/Year;;RecNum;117;/RecNum;;DisplayText;(De Silva;style face=”italic”; et al.;/style;, 2007);/DisplayText;;record;;rec-number;117;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;117;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;De Silva, CS;/author;;author;Weatherhead, EK;/author;;author;Knox, J Wo;/author;;author;Rodriguez-Diaz, JA;/author;;/authors;;/contributors;;titles;;title;Predicting the impacts of climate change—A case study of paddy irrigation water requirements in Sri Lanka;/title;;secondary-title;Agricultural water management;/secondary-title;;/titles;;periodical;;full-title;Agricultural water management;/full-title;;/periodical;;pages;19-29;/pages;;volume;93;/volume;;number;1-2;/number;;dates;;year;2007;/year;;/dates;;isbn;0378-3774;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(De Silva et al., 2007).

Climate change impacts on soil water balance leads to changes of soil evaporation and plant transpiration and the crop growth period may shorten in the future impacting on water productivity. Crop yields affected by climate change are projected to be different in various areas, in some areas crop yields may increase and for other areas it may decrease depending on the latitude of the area and irrigation application. Modelling results showed that an increase in precipitation increases crop yield and crop yield is more sensitive to the precipitation than temperature ADDIN EN.CITE ;EndNote;;Cite;;Author;Kang;/Author;;Year;2009;/Year;;RecNum;116;/RecNum;;DisplayText;(Kang;style face=”italic”; et al.;/style;, 2009);/DisplayText;;record;;rec-number;116;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;116;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Kang, Yinhong;/author;;author;Khan, Shahbaz;/author;;author;Ma, Xiaoyi;/author;;/authors;;/contributors;;titles;;title;Climate change impacts on crop yield, crop water productivity and food security–A review;/title;;secondary-title;Progress in Natural Science;/secondary-title;;/titles;;periodical;;full-title;Progress in Natural Science;/full-title;;/periodical;;pages;1665-1674;/pages;;volume;19;/volume;;number;12;/number;;dates;;year;2009;/year;;/dates;;isbn;1002-0071;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Kang et al., 2009). With reduced water availability in the future, soils of high water holding capacity would be better to reduce the impact of drought while maintaining crop yield. With the temperature increasing and precipitation fluctuations in the future, water availability and crop production are likely to decrease in the future. If the irrigated areas are expanded, the total crop production will increase, however, food and environmental quality may degrade ADDIN EN.CITE ;EndNote;;Cite;;Author;Roudier;/Author;;Year;2011;/Year;;RecNum;58;/RecNum;;DisplayText;(Roudier;style face=”italic”; et al.;/style;, 2011);/DisplayText;;record;;rec-number;58;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;58;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Roudier, Philippe;/author;;author;Sultan, Benjamin;/author;;author;Quirion, Philippe;/author;;author;Berg, Alexis;/author;;/authors;;/contributors;;titles;;title;The impact of future climate change on West African crop yields: What does the recent literature say?;/title;;secondary-title;Global Environmental Change;/secondary-title;;/titles;;periodical;;full-title;Global Environmental Change;/full-title;;/periodical;;pages;1073-1083;/pages;;volume;21;/volume;;number;3;/number;;dates;;year;2011;/year;;/dates;;isbn;0959-3780;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Roudier et al., 2011).

This study is focused on irrigation water saving techniques as a means of maintaining food production in the future in case of climate changes. The future climate change may be reduction in rainfall amount and increase in temperature thus increasing evapotranspiration and hence reduction in crop yields.

2.3 Crop Water Requirement (CWR)
The crop water requirement (ETc) is the depth (or amount) of water needed to meet the water loss through evapotranspiration or the amount of water needed by the various crops to grow optimally ADDIN EN.CITE ;EndNote;;Cite;;Author;Savva;/Author;;Year;2002;/Year;;RecNum;71;/RecNum;;DisplayText;(Savva and Frenken, 2002);/DisplayText;;record;;rec-number;71;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;71;/key;;/foreign-keys;;ref-type name=”Book”;6;/ref-type;;contributors;;authors;;author;Savva, Andreas P;/author;;author;Frenken, Karen;/author;;/authors;;/contributors;;titles;;title;Crop water requirements and irrigation scheduling;/title;;/titles;;dates;;year;2002;/year;;/dates;;publisher;FAO Sub-Regional Office for East and Southern Africa Harare;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Savva and Frenken, 2002). The crop water need mainly depends on:
The climate: in a sunny and hot climate crops need more water per day than in a cloudy and cool climate.

The crop type: crops like maize or sugarcane need more water than crops like millet or sorghum.

The growth stage of the crop; fully grown crops need more water than crops that have just been planted.

A number of techniques have been developed and applied in simulating crop water requirements. Some of the common models include; AQUA Crop, CROPWAT, Cropsyst, CERES and DDSSAT. The models are discussed as follows;
2.3.1 CROPWAT modelUnderstanding crop water requirements (CWR) in semi-arid region is essential for better irrigation practices, scheduling and efficient use of water since the water supply through rainfall is limited. ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Bouraima;/Author;;Year;2015;/Year;;RecNum;96;/RecNum;;DisplayText;Bouraima;style face=”italic”; et al.;/style; (2015);/DisplayText;;record;;rec-number;96;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;96;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Bouraima, Abdel-Kabirou;/author;;author;Weihua, Zhang;/author;;author;Chaofu, Wei;/author;;/authors;;/contributors;;titles;;title;Irrigation water requirements of rice using Cropwat model in Northern Benin;/title;;secondary-title;International Journal of Agricultural and Biological Engineering;/secondary-title;;/titles;;periodical;;full-title;International Journal of Agricultural and Biological Engineering;/full-title;;/periodical;;pages;58;/pages;;volume;8;/volume;;number;2;/number;;dates;;year;2015;/year;;/dates;;isbn;1934-6344;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;Bouraima et al. (2015) estimated the crop reference and actual evapotranspiration (ETo and ETc) respectively and the irrigation water requirement of rice in Benin’s sub-basin of Niger River (BSBNR), using CROPWAT model. The Crop coefficients (Kc) from the phenomenological stages of rice were applied to adjust and estimate the actual evapotranspiration ETc through a water balance of the irrigation water requirements (IR). From the results the BSBNR crop evapotranspiration ETc and the crop irrigation requirements were estimated at 651 mm and 383 mm, respectively in rainy season and 920 mm and 1 148 mm, respectively within a dry season.

ADDIN EN.CITE <EndNote><Cite AuthorYear=”1″><Author>Karanja</Author><Year>2006</Year><RecNum>97</RecNum><DisplayText>Karanja (2006)</DisplayText><record><rec-number>97</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>97</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Karanja, Fredrick K</author></authors></contributors><titles><title>Cropwat model analysis of crop water use in six districts in Kenya</title><secondary-title>CEEPA DP35, University of Pretoria, South Africa</secondary-title></titles><periodical><full-title>CEEPA DP35, University of Pretoria, South Africa</full-title></periodical><dates><year>2006</year></dates><urls></urls></record></Cite></EndNote>Karanja (2006) used CROPWAT method to evaluate the crop water requirements of six selected agricultural districts, Kiambu, Makueni, Kwale, Laikipia, Vihiga and Migori, distributed across six provinces of Kenya: Central, Eastern, Coast, Rift Valley, Western and Nyanza respectively. The districts were selected to reflect the diversity of the country’s agro-ecological zones. Their results showed that an increase in temperature increases the percentage change in crop water use and that the changes in crop water use from the output of the CCCM scenario were lower than those from the GFDL3 for all the districts studied.

2.3.2 AQUA Crop ModelThe FAO Aqua Crop model predicts crop productivity, water requirement, and water use efficiency (WUE) under water-limiting conditions. The ease of use of the Aqua Crop model, the low requirement of input parameters, and its sufficient degree of simulation accuracy make it a valuable tool for estimating crop productivity. It has been used under rainfed conditions, supplementary, deficit irrigation, and on-farm water management strategies for improving the efficiency of water use in agriculture ADDIN EN.CITE ;EndNote;;Cite;;Author;Heng;/Author;;Year;2009;/Year;;RecNum;94;/RecNum;;DisplayText;(Heng;style face=”italic”; et al.;/style;, 2009);/DisplayText;;record;;rec-number;94;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;94;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Heng, Lee Kheng;/author;;author;Hsiao, Theodore;/author;;author;Evett, Steve;/author;;author;Howell, Terry;/author;;author;Steduto, Pasquale;/author;;/authors;;/contributors;;titles;;title;Validating the FAO AquaCrop model for irrigated and water deficient field maize;/title;;secondary-title;Agronomy Journal;/secondary-title;;/titles;;periodical;;full-title;Agronomy Journal;/full-title;;/periodical;;pages;488-498;/pages;;volume;101;/volume;;number;3;/number;;dates;;year;2009;/year;;/dates;;isbn;1435-0645;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Heng et al., 2009). ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Salemi;/Author;;Year;2011;/Year;;RecNum;95;/RecNum;;DisplayText;Salemi;style face=”italic”; et al.;/style; (2011);/DisplayText;;record;;rec-number;95;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;95;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Salemi, Hamidreza;/author;;author;Soom, Mohd Amin Mohd;/author;;author;Lee, Teang Shui;/author;;author;Mousavi, Sayed Farhad;/author;;author;Ganji, Arman;/author;;author;Yusoff, Mohd Kamil;/author;;/authors;;/contributors;;titles;;title;Application of AquaCrop model in deficit irrigation management of winter wheat in arid region;/title;;secondary-title;African Journal of Agricultural Research;/secondary-title;;/titles;;periodical;;full-title;African Journal of Agricultural Research;/full-title;;/periodical;;pages;2204-2215;/pages;;volume;6;/volume;;number;10;/number;;dates;;year;2011;/year;;/dates;;isbn;1991-637X;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;Salemi et al. (2011) studied the potential of Aqua Crop model in deficit irrigation practice for winter wheat in Gavkhuni river basin. From the results it was observed that the model provided excellent simulations of canopy cover, grain yield and water productivity and found that water productivity for the studied crop was in the range of 0.91 to 1.49 kg m-3 and its maximum value was in 40% deficit irrigation treatment.
ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Darko;/Author;;Year;2016;/Year;;RecNum;98;/RecNum;;DisplayText;Darko;style face=”italic”; et al.;/style; (2016);/DisplayText;;record;;rec-number;98;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;98;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Darko, Ransford Opoku;/author;;author;Shouqi, Yuan;/author;;author;Haofang, Yan;/author;;author;Liu, Junping;/author;;author;Abbey, Agnes;/author;;/authors;;/contributors;;titles;;title;Calibration and validation of AquaCrop for deficit and full irrigation of tomato;/title;;secondary-title;International Journal of Agricultural and Biological Engineering;/secondary-title;;/titles;;periodical;;full-title;International Journal of Agricultural and Biological Engineering;/full-title;;/periodical;;pages;104-110;/pages;;volume;9;/volume;;number;3;/number;;dates;;year;2016;/year;;/dates;;isbn;1934-6352;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;Darko et al. (2016) carried out field experiments in the tropical humid coastal savanna zone in Mfantseman district of the Central Region of Ghana to calibrate and test Aqua Crop model for tomato (Lycopersicon esculentum) grown under deficit and full irrigation. They used data from the first experiment to calibrate the model while data obtained from the second experiment were used to validate the model. The calibrated Aqua Crop model concentrated on its performance to predict crop yield and seasonal crop water requirement where four treatments were investigated: no irrigation after plant establishment, 50% ETc restoration, 100% ETc restoration up to beginning of flowering, then 50% ETc restoration and 100% ETc restoration. From the results it was revealed that the model was able to simulate the seasonal water requirements to an appreciable degree in both experiments.
In this study AQUA Crop model will be used because of its ability to simulate yields in response to water, simplicity and small number of parameter requirement.
2.4 Water Saving Irrigation StrategiesThere are several water saving irrigation strategies which include scientific irrigation scheduling (deficit irrigation), managed full season drought management, Partial Season Drought Management and mulching systems ADDIN EN.CITE ;EndNote;;Cite;;Author;Evans;/Author;;Year;2008;/Year;;RecNum;115;/RecNum;;DisplayText;(Evans and Sadler, 2008);/DisplayText;;record;;rec-number;115;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;115;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Evans, Robert G;/author;;author;Sadler, E John;/author;;/authors;;/contributors;;titles;;title;Methods and technologies to improve efficiency of water use;/title;;secondary-title;Water resources research;/secondary-title;;/titles;;periodical;;full-title;Water resources research;/full-title;;/periodical;;volume;44;/volume;;number;7;/number;;dates;;year;2008;/year;;/dates;;isbn;1944-7973;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Evans and Sadler, 2008).

2.4.1 Deficit IrrigationDeficit irrigation is the process of applying less irrigation water than the full requirement of the crop that is the crop is to face certain amount of stress. ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Haidula;/Author;;Year;2016;/Year;;RecNum;104;/RecNum;;DisplayText;Haidula (2016);/DisplayText;;record;;rec-number;104;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;104;/key;;/foreign-keys;;ref-type name=”Thesis”;32;/ref-type;;contributors;;authors;;author;Haidula, Simon;/author;;/authors;;/contributors;;titles;;title;Irrigation water use and vegetable production efficiency assessment between sprinkler and drip irrigation systems at North Central Namibia (NCN):(Study on three vegetable crops: tomato, cabbage, and pepper);/title;;/titles;;dates;;year;2016;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;Haidula (2016), defined Deficit Irrigation as a regulated irrigation techniques that minimize water use, with minimal impacts on crop yield and quality to ensure sustainable agricultural productivity. ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Salokhe;/Author;;Year;2005;/Year;;RecNum;75;/RecNum;;DisplayText;Salokhe;style face=”italic”; et al.;/style; (2005);/DisplayText;;record;;rec-number;75;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;75;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Salokhe, VM;/author;;author;Babel, MS;/author;;author;Tantau, HJ;/author;;/authors;;/contributors;;titles;;title;Water requirement of drip irrigated tomatoes grown in greenhouse in tropical environment;/title;;secondary-title;Agricultural Water Management;/secondary-title;;/titles;;periodical;;full-title;Agricultural water management;/full-title;;/periodical;;pages;225-242;/pages;;volume;71;/volume;;number;3;/number;;dates;;year;2005;/year;;/dates;;isbn;0378-3774;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;Salokhe et al. (2005) carried out an experiment on four different levels of drip fertigated irrigation equivalent to 100, 75, 50 and 25% of crop evapotranspiration (ETc), based on Penman–Monteith (PM) method, for their effect on crop growth, crop yield, and water productivity. They grew Tomato (Lycopersicon esculentum, Troy 489variety) in a poly-net greenhouse and compared the results with the open cultivation system as a control. Their results revealed that drip irrigation at 75% of ETc provided the maximum crop yields and irrigation water productivity. In an alternative irrigation level varying technique, ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Ku?çu;/Author;;Year;2014;/Year;;RecNum;76;/RecNum;;DisplayText;Ku?çu;style face=”italic”; et al.;/style; (2014);/DisplayText;;record;;rec-number;76;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;76;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Ku?çu, Hayrettin;/author;;author;Turhan, Ahmet;/author;;author;Demir, Ali Osman;/author;;/authors;;/contributors;;titles;;title;The response of processing tomato to deficit irrigation at various phenological stages in a sub-humid environment;/title;;secondary-title;Agricultural Water Management;/secondary-title;;/titles;;periodical;;full-title;Agricultural water management;/full-title;;/periodical;;pages;92-103;/pages;;volume;133;/volume;;dates;;year;2014;/year;;/dates;;isbn;0378-3774;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;Ku?çu et al. (2014) conducted field studies in Bursa province, Turkey to determine the response of processing tomato (Lycopersicon esculentum Mill) to deficit irrigation in order to guide programs for the development of improved irrigation management practices for sub-humid zones. They subjected Industrial tomato plants to different levels of irrigation using a drip system in the field on a clay-loam Entisol soil for two years where well – watered plants were irrigated at 100% crop evapotranspiration (ETc) at three day intervals. In other treatments irrigation was not applied during the vegetative, flowering, yield formation or ripening stages or during combination of these stages. The results from the authors showed that full irrigation during the whole growing season was preferable for higher yield and net income. Recommendations were that the application of full irrigation until the beginning of the fruit ripening stage and cessation of full irrigation after that time was optimal.
Deficit irrigation allows saving up to 20 – 40% irrigation water at yield reductions below 10%. The recommended deficit irrigation levels are thus 100% ETc, 90%ETc, 80%ETC, 70%ETC and 60%ETc. ADDIN EN.CITE ;EndNote;;Cite;;Author;Kögler;/Author;;Year;2017;/Year;;RecNum;121;/RecNum;;DisplayText;(Kögler and Söffker, 2017);/DisplayText;;record;;rec-number;121;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;121;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Kögler, F;/author;;author;Söffker, D;/author;;/authors;;/contributors;;titles;;title;Water (stress) models and deficit irrigation: System-theoretical description and causality mapping;/title;;secondary-title;Ecological Modelling;/secondary-title;;/titles;;periodical;;full-title;Ecological Modelling;/full-title;;/periodical;;pages;135-156;/pages;;volume;361;/volume;;dates;;year;2017;/year;;/dates;;isbn;0304-3800;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Kögler and Söffker, 2017). The studies did not consider the effect of mulching in the water productivity of tomatoes as will be taken into account in this study.
2.4.2 MulchingMulching involves covering, as of paddy straw, sugarcane bark, dry grass, trees leaves and even newspaper, wool, animal manure, saw dust, wood chips and peat moss, spread on the ground around plants for conservation of soil moisture, improving fertility and health of the soil, reducing weed growth and enhancing the visual appeal of the area ADDIN EN.CITE ;EndNote;;Cite;;Author;Jordán;/Author;;Year;2011;/Year;;RecNum;100;/RecNum;;DisplayText;(Jordán;style face=”italic”; et al.;/style;, 2011);/DisplayText;;record;;rec-number;100;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;100;/key;;/foreign-keys;;ref-type name=”Book Section”;5;/ref-type;;contributors;;authors;;author;Jordán, Antonio;/author;;author;Zavala, Lorena M;/author;;author;Muñoz-Rojas, Miriam;/author;;/authors;;/contributors;;titles;;title;Mulching, effects on soil physical properties;/title;;secondary-title;Encyclopedia of agrophysics;/secondary-title;;/titles;;pages;492-496;/pages;;dates;;year;2011;/year;;/dates;;publisher;Springer;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Jordán et al., 2011). There are also two types of plastic mulches which are transparent and black, that are used to determine the productivity of different crops ADDIN EN.CITE ;EndNote;;Cite;;Author;Yaghi;/Author;;Year;2013;/Year;;RecNum;59;/RecNum;;DisplayText;(Yaghi;style face=”italic”; et al.;/style;, 2013);/DisplayText;;record;;rec-number;59;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;59;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Yaghi, T;/author;;author;Arslan, A;/author;;author;Naoum, F;/author;;/authors;;/contributors;;titles;;title;Cucumber (Cucumis sativus, L.) water use efficiency (WUE) under plastic mulch and drip irrigation;/title;;secondary-title;Agricultural water management;/secondary-title;;/titles;;periodical;;full-title;Agricultural Water Management;/full-title;;/periodical;;pages;149-157;/pages;;volume;128;/volume;;dates;;year;2013;/year;;/dates;;isbn;0378-3774;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Yaghi et al., 2013).

ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Saeed;/Author;;Year;2009;/Year;;RecNum;77;/RecNum;;DisplayText;Saeed and Ahmad (2009);/DisplayText;;record;;rec-number;77;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;77;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Saeed, Rafat;/author;;author;Ahmad, Rafiq;/author;;/authors;;/contributors;;titles;;title;Vegetative growth and yield of tomato as affected by the application of organic mulch and gypsum under saline rhizosphere;/title;;secondary-title;Pak. J. Bot;/secondary-title;;/titles;;periodical;;full-title;Pak. J. Bot;/full-title;;/periodical;;pages;3093-3105;/pages;;volume;41;/volume;;number;6;/number;;dates;;year;2009;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;Saeed and Ahmad (2009) carried out a study to observe the effects of organic mulch with and without gypsum on vegetative growth and reproductive yield of tomato plant (Lycopersicon esculentum Mill.) under control (non-saline) and saline rhizosphere. The authors’ results revealed a significant decrease in vegetative growth and reproductive yield proportionate to increasing salinity levels. The application of mulch treatments revealed significant increase under both the conditions. The application of organic mulches with or without gypsum to soil being irrigated with saline water increases the yield by reducing salinity hazards which could be quantified on growth of tomato plant.

ADDIN EN.CITE <EndNote><Cite AuthorYear=”1″><Author>Ortiz</Author><Year>2015</Year><RecNum>78</RecNum><DisplayText>Ortiz (2015)</DisplayText><record><rec-number>78</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>78</key></foreign-keys><ref-type name=”Book”>6</ref-type><contributors><authors><author>Ortiz, Vicente</author></authors></contributors><titles><title>Effects of Different Mulching Techniques for Improving Irrigation Water Use Efficiency and Yields for Cherry Tomato Produced by Del Cabo Farm in Baja California, México</title></titles><dates><year>2015</year></dates><publisher>Wageningen University</publisher><urls></urls></record></Cite></EndNote>Ortiz (2015) carried out a study to evaluate different management techniques to increase soil water status, enhance water use efficiency, plant performance, crop yield and fruit quality using treatments of different compost rates in combination with different mulching techniques such as garlic straw, oat straw, plastic and no mulch. Plant performance (plant height, canopy density and canopy volume) were monitored at weekly interval, together with crop yield (specific fruit weight and weekly yields) and fruit quality (brix degrees and fruit size). The study revealed that the use of straw mulch has the potential to increase soil water retention and may also increase yields and improve soil quality but additional research is needed to look at long-term benefits in terms of fruit yield, soil quality, potential water savings and profitability. The effect of deficit irrigation on the productivity of tomatoes was not considered as is proposed in this study. This study will assess the effect of different grass mulch densities on the water productivity of tomatoes.
2.5 Strategies for Improving Vegetable Farming ProductivityThere are several strategies for improving vegetable farming productivity that increase yield. They include; crop rotation, irrigation, mulching and cultural practices ADDIN EN.CITE <EndNote><Cite><Author>La Pena</Author><Year>2007</Year><RecNum>122</RecNum><DisplayText>(La Pena and Hughes, 2007)</DisplayText><record><rec-number>122</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>122</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>La Pena, R de</author><author>Hughes, J</author></authors></contributors><titles><title>Improving vegetable productivity in a variable and changing climate</title></titles><dates><year>2007</year></dates><urls></urls></record></Cite></EndNote>(La Pena and Hughes, 2007).

2.5.1 Crop rotation
Good crop rotations minimize pests and disease build up and enhances soil fertility.

2.5.2 Water-saving irrigation management.
The quality and efficiency of water management determine the yield and quality of vegetable products. The optimum frequency and amount of applied water is depends on climatic and weather conditions, crop species, variety, stage of growth and rooting characteristics, soil water retention capacity and texture, irrigation system and management factor.

2.5.3 Cultural practices that conserve water and protect crops:
Various crop management practices such as mulching and the use of shelters and raised beds help to conserve soil moisture, prevent soil degradation, and protect vegetables from heavy rains, high temperatures, and flooding. The use of organic and inorganic mulches is common in high-value vegetable production systems. These protective coverings help reduce evaporation, moderate soil temperature, reduce soil runoff and erosion, protect fruits from direct contact with soil and minimize weed growth. Also, the use of organic materials as mulch can help enhance soil fertility, structure and other soil properties.

This study will employ irrigation and mulching systems as strategies for improving tomato water productivity.

2.6 Interactive Impacts of Deficit Irrigation and MulchingDeficit irrigation and mulching are both techniques of conserving moisture in the soil. Their combination is expected to increase the water productivity of tomato. AUTHOR * FirstCap * MERGEFORMAT Fereres and Soriano, (2006) conducted a field experiment at Water Technology Centre, to study the effect of drip irrigation levels and mulching on tomato productivity laid out in strip plot design with three drip irrigation levels as main treatments (100% ETc, 80% ETc, 60% ETc) and four mulches (bio-degradable mulch, polythene mulch, paddy straw and no mulch) as the sub treatments with three replications. From the author’s study, it was concluded that drip irrigation scheduling at 100% ETc with application of polythene mulch would be the best combination for getting higher tomato productivity under the Agro climatic conditions of the semi – arid tropics.
HYPERLINK l “_ENREF_40” o “Mukherjee, 2018 #58″ ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Mukherjee;/Author;;Year;2018;/Year;;RecNum;58;/RecNum;;DisplayText;Mukherjee;style face=”italic”; et al.;/style; (2018);/DisplayText;;record;;rec-number;58;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;58;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Mukherjee, Asis;/author;;author;Sarkar, S;/author;;author;Sarkar, A;/author;;/authors;;/contributors;;titles;;title;Productivity and Profitability of Tomato Due to Irrigation Frequency and Mulch;/title;;secondary-title;International Journal of Vegetable Science;/secondary-title;;/titles;;periodical;;full-title;International Journal of Vegetable Science;/full-title;;/periodical;;pages;43-57;/pages;;volume;24;/volume;;number;1;/number;;dates;;year;2018;/year;;/dates;;isbn;1931-5260;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;Mukherjee et al. (2018) grew tomato during November-March 2003-2005 under the irrigation regimes: rainfed, irrigation when cumulative pan evaporation (CPE) reached 50 mm (CPE50), or 25 mm (CPE25),with mulch treatments: none, rice straw, white, or black polyethylene. The results presented revealed that the fruit yield increased with increased irrigation frequency and mulch. Mulching enhanced fruit yield by 23-58% over no mulch. It was concluded that the use of black polyethylene, when water is scarce (rainfed, CPE50), had the potential to increase income compared to plants in bare soil when water is plentiful. As seen from the past studies tomato is very sensitive to moisture stress and the water stress levels will be monitored closely at 100% ETc, 90% ETc, 80% ETc, and 70% ETc in combination with mulching in the present study unlike in many studies where the stress levels are widely apart, for example 100% ETc, 80% ETc and 60% ETc.

The combined effects of deficit irrigation under drip irrigation system and mulches on yield and water-use efficiency on tomato production at Miawa Farmer Training center, south Wollo, and Kallu worda during 2016 irrigation season was investigated. A factorial combination of three levels of water (namely 70%, 80% and 90% ETc) combined with three mulch treatments (namely, without mulch (WM), sugarcane mulch (SM) and bulrush mulch (BM)) with three replications was used. The highest water use efficiency was obtained 142.96 kg/ha/mm with 80% water application under sugarcane mulch. The study thus reveals that drip irrigation with mulch has an explicit role in increasing the yield and water productivity of tomato. However the effect of full water supply and under supply was not studied to assess the impact of all the possible water levels on tomato water requirement ADDIN EN.CITE ;EndNote;;Cite;;Author;Amare;/Author;;Year;2017;/Year;;RecNum;60;/RecNum;;DisplayText;(Amare;style face=”italic”; et al.;/style;, 2017);/DisplayText;;record;;rec-number;60;/rec-number;;foreign-keys;;key app=”EN” db-id=”r5ws5edxa0d296e0d0pxrx5nsf2s2saavzr0″;60;/key;;/foreign-keys;;ref-type name=”Thesis”;32;/ref-type;;contributors;;authors;;author;Amare, Haileslassie;/author;;author;Asfaw, Kebede;/author;;author;Kassahun, Alebachew;/author;;/authors;;/contributors;;titles;;title;Evaluation of Deficit Irrigation and Mulching on Water Productivity of Tomato (Lycopersicon esculentum Mill) Under Drip Irrigation System at Kallu Woreda, South Wollo, Ethiopia;/title;;/titles;;dates;;year;2017;/year;;/dates;;publisher;Harmaya University;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Amare et al., 2017). However the effect of lower water levels was not taken into account and also such study will be done in Njoro sub county because the conditions are different of those in which studies have been undertaken.
In this study the interactive impacts of both deficit drip – irrigation and mulching systems will be used to evaluate the tomato water productivity because of their ability to save irrigation water.

2.7 VegetablesVegetables are an essential component of human diet as they are the only source of nutrients, vitamins and minerals. They are good remunerative to the farmer as they fetch higher price in the market, however like other crops, they are also being affected by the consequences of climate change. Under changing climatic conditions crop failures, shortage of yields, reduction in quality and increasing pest and disease problems are common and they render the vegetable cultivation unprofitable. As many physiological processes and enzymatic activities are temperature dependent, they are going to be largely effected. Drought and salinity are the important consequences of increase in temperature lowering vegetable cultivation ADDIN EN.CITE ;EndNote;;Cite;;Author;Ayyogari;/Author;;Year;2014;/Year;;RecNum;123;/RecNum;;DisplayText;(Ayyogari;style face=”italic”; et al.;/style;, 2014);/DisplayText;;record;;rec-number;123;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;123;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Ayyogari, Kondinya;/author;;author;Sidhya, Palash;/author;;author;Pandit, MK;/author;;/authors;;/contributors;;titles;;title;Impact of climate change on vegetable cultivation-a review;/title;;secondary-title;International Journal of Agriculture, Environment and Biotechnology;/secondary-title;;/titles;;periodical;;full-title;International Journal of Agriculture, Environment and Biotechnology;/full-title;;/periodical;;pages;145;/pages;;volume;7;/volume;;number;1;/number;;dates;;year;2014;/year;;/dates;;isbn;0974-1712;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Ayyogari et al., 2014). In this study tomato, which is a vegetable will be assessed because of its shorter maturity period and high prices in the market hence more profitable to the farmer.

2.8 Reference Evapotranspiration ETO Estimation MethodsReference evapotranspiration (ETo) is the rate of evapotranspiration from a hypothetical reference crop with an assumed crop height of 0.12 m, a fixed surface resistance of 70 sec m-1 and an albedo of 0.23, closely resembling the evapotranspiration from an extensive surface of green grass of uniform height, actively growing, well-watered, and completely shading the ground. ETo can be estimated using different methods depending on the availability of climatic data. The different methods of ETo estimation are FAO-24 Penman –Monteith, FAO-24 Blaney-Criddle, Hargreaves and Christiansen Pan ADDIN EN.CITE ;EndNote;;Cite;;Author;George;/Author;;Year;2012;/Year;;RecNum;81;/RecNum;;DisplayText;(George and Raghuwanshi, 2012);/DisplayText;;record;;rec-number;81;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;81;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;George, Biju A;/author;;author;Raghuwanshi, NS;/author;;/authors;;/contributors;;titles;;title;Inter-comparison of reference evapotranspiration estimated using six methods with data from four climatological stations in India;/title;;secondary-title;Journal of Indian Water Resources Society;/secondary-title;;/titles;;periodical;;full-title;Journal of Indian Water Resources Society;/full-title;;/periodical;;pages;15-22;/pages;;volume;32;/volume;;number;3? 4;/number;;dates;;year;2012;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(George and Raghuwanshi, 2012). The methods are discussed as follows;
2.8.1 Blaney-Criddle MethodThe Blaney Criddle equation is used to estimate the reference evapotranspiration and is simple with low parameter requirement ADDIN EN.CITE ;EndNote;;Cite;;Author;Xu;/Author;;Year;2002;/Year;;RecNum;83;/RecNum;;DisplayText;(Xu and Singh, 2002);/DisplayText;;record;;rec-number;83;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;83;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Xu, C-Y;/author;;author;Singh, VP;/author;;/authors;;/contributors;;titles;;title;Cross comparison of empirical equations for calculating potential evapotranspiration with data from Switzerland;/title;;secondary-title;Water Resources Management;/secondary-title;;/titles;;periodical;;full-title;Water Resources Management;/full-title;;/periodical;;pages;197-219;/pages;;volume;16;/volume;;number;3;/number;;dates;;year;2002;/year;;/dates;;isbn;0920-4741;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Xu and Singh, 2002). It is expressed as;
(2.2)
Where,
ETO = potential evapotranspiration from a reference crop for the period in which p is expressed (mm day-1),
Ta = mean temperature (?C)
p = percentage of total daytime hours for the used period (daily or monthly) out of total daytime hours of the year (365 × 12). The value of p can be estimated from table1 (dimensionless).

k = monthly consumptive use coefficient, depending on vegetation type, location and season and for the growing season (May to October), k varies from 0.5 for orange tree to 1.2 for dense natural vegetation (dimensionless).
Blaney Criddle method of estimating reference evapotranspiration will be used in this study because of its simplicity and low parameter requirement.

2.8.2 Hargreaves MethodThe Hargreaves equation is simple method for estimating reference evapotranspiration and requires few parameters ADDIN EN.CITE ;EndNote;;Cite;;Author;Talaee;/Author;;Year;2014;/Year;;RecNum;84;/RecNum;;DisplayText;(Talaee, 2014);/DisplayText;;record;;rec-number;84;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;84;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Talaee, Parisa Hosseinzadeh;/author;;/authors;;/contributors;;titles;;title;Performance evaluation of modified versions of Hargreaves equation across a wide range of Iranian climates;/title;;secondary-title;Meteorology and Atmospheric Physics;/secondary-title;;/titles;;periodical;;full-title;Meteorology and Atmospheric Physics;/full-title;;/periodical;;pages;65-70;/pages;;volume;126;/volume;;number;1-2;/number;;dates;;year;2014;/year;;/dates;;isbn;0177-7971;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Talaee, 2014). It has not been used by most researchers and will be used in this study to estimate the crop water requirement and compare the results with the Blaney Criddle method results for accuracy. It is expressed as;
(2.3)
Where,
ETO = grass reference evapotranspiration (mm day-1),
Tmax, Tmin and Ta = are the maximum, minimum and mean air temperatures (oC), respectively.

Ra = the water equivalent of the extraterrestrial radiation (mm day-1)
The water equivalent of the extraterrestrial radiation, Ra According to ADDIN EN.CITE ;EndNote;;Cite AuthorYear=”1″;;Author;Allen;/Author;;Year;1998;/Year;;RecNum;85;/RecNum;;DisplayText;Allen;style face=”italic”; et al.;/style; (1998);/DisplayText;;record;;rec-number;85;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;85;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Allen, Richard G;/author;;author;Pereira, Luis S;/author;;author;Raes, Dirk;/author;;author;Smith, Martin;/author;;/authors;;/contributors;;titles;;title;Crop evapotranspiration-Guidelines for computing crop water requirements-FAO Irrigation and drainage paper 56;/title;;secondary-title;FAO, Rome;/secondary-title;;/titles;;periodical;;full-title;FAO, Rome;/full-title;;/periodical;;pages;D05109;/pages;;volume;300;/volume;;number;9;/number;;dates;;year;1998;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;Allen et al. (1998), is expressed as;
(2.4)
Where,
Gsc = Solar constant = 0.0820MJ/M2/min
dr = Inverse relative distance Earth – Sun
(2.5)
J = No. of the day in the year between 1 (1stJanuary) and 365 or 366 (31st December)
?s = sunset hour angle (rad)

? = latitude (rad)
? = Solar declination
(2.6)
In this study the Hargreaves method will not be used to estimate reference evapotranspiration because though they are simple and requres low parameter requirement and for comparison between the methods.

2.8.3 Penman–Monteith methodThe Penman – Monteith method is considered as a standard and the most precise method to estimate reference evapotranspiration though its limitation is several parameter requirement ADDIN EN.CITE ;EndNote;;Cite;;Author;Sentelhas;/Author;;Year;2010;/Year;;RecNum;112;/RecNum;;DisplayText;(Sentelhas;style face=”italic”; et al.;/style;, 2010);/DisplayText;;record;;rec-number;112;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;112;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Sentelhas, Paulo C;/author;;author;Gillespie, Terry J;/author;;author;Santos, Eduardo A;/author;;/authors;;/contributors;;titles;;title;Evaluation of FAO Penman–Monteith and alternative methods for estimating reference evapotranspiration with missing data in Southern Ontario, Canada;/title;;secondary-title;Agricultural Water Management;/secondary-title;;/titles;;periodical;;full-title;Agricultural water management;/full-title;;/periodical;;pages;635-644;/pages;;volume;97;/volume;;number;5;/number;;dates;;year;2010;/year;;/dates;;isbn;0378-3774;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Sentelhas et al., 2010). The function is expressed as;
(2.1)
Where,
ET0 = grass reference evapotranspiration (mm day-1),
? = the slope of the saturated vapor pressure curve (kPa oC-1),
(2.2)
Rn = the net radiation (MJ m-2 day-1),
G = the soil heat flux density (MJ m-2). It is null for daily estimates,
T = daily mean air temperature (oC) at 2m based on the average of maximum and minimum temperature
(2.3)
U2 = average wind speed at 2m height (ms-1)
es = the saturation vapour pressure (kPa),
(2.4)
(2.5)
(2.6)
ea = the actual vapour pressure (kPa)
(2.7)
(2.8)
e°(Twet) = saturation vapour pressure at wet bulb temperature kPa
Twet = Wet bulb temperature
? psy = psychrometric constant of the instrument kPa °C-1
(2.9)
? = psychrometric constant kPa °C-1
P = atmospheric pressure kPa
? = latent heat of vaporization, 2.45 MJ kg-1
cp = specific heat at constant pressure, 1.013 10-3 MJ kg-1 °C-1
? = ratio molecular weight of water vapour/dry air = 0.622
(2.10)
P = atmospheric pressure kPa
z = elevation above sea level m
Tdry-Twet = wet bulb depression, with Tdry the dry bulb and Twet the wet bulb temperature °C
Tdry = Dry bulb temperature;oij
(es – ea) = the saturation vapour pressure deficit (?e, kPa ) and
? = the psychrometric constant (0.0677 kPa oC)
The Penman – Monteith method is considered as a standard and the most precise method to estimate reference evapotranspiration and will be used in this study.

CHAPTER THREEMATERIALS AND METHODS3.1 Description of Study Area3.1.1 Location of Study AreaThe study will be carried out in Njoro Sub County, Nakuru County. Njoro Sub County covers an area of about 780 km2. Njoro Town is the headquarters of Njoro Sub County and is located about 200 km North West of Nairobi and 18 km south west of Nakuru Town. With an average altitude of 2400 meters above sea level, Njoro lies between Latitude 0º 15″0 and 0º 42″30 south and Longitude 35º 45″0 and 36º 10″ 0 East (Figure 3.1).

1022350762000100012522726650319087453340
Figure 3. SEQ Figure_3. * ARABIC 1 : Location of Njoro Sub County3.1.2 Climatic conditionsNjoro’s climate is classified as warm and temperate. Annual rainfall averages 937 mm. The least amount of rainfall occurs in January with the average being 20 mm. Most of the precipitation falls in April, averaging 140 mm. There are two rainfall seasons – long and short rains. The short rains yield on average 423 mm while the long rains yield 337 mm. The average mean annual temperature for the area is 21° C being highest on average in March, at around 17.3 °C while August is the coldest month, with temperatures averaging 15.1 °C. The area has a bimodal precipitation pattern with long rains occurring from April to May and short rains occurring from July to August. Mean annual rainfall measured at Egerton University from 1987-2016 was 1073 mm. The average mean annual temperature for the area is 21° C.

3.1.3 Soil ConditionsThe drainage classes of the soil in Njoro sub county range from poorly drained, moderately well drained, well drained to excessively drained, with textures ranging from loam, clay to clay loam and structures in the range of moderately strong to strong ADDIN EN.CITE <EndNote><Cite><Author>Mainuri</Author><Year>2013</Year><RecNum>110</RecNum><DisplayText>(Mainuri and Owino, 2013)</DisplayText><record><rec-number>110</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>110</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Mainuri, Zachary G</author><author>Owino, James O</author></authors></contributors><titles><title>Effects of land use and management on aggregate stability and hydraulic conductivity of soils within River Njoro Watershed in Kenya</title><secondary-title>International Soil and Water Conservation Research</secondary-title></titles><periodical><full-title>International Soil and Water Conservation Research</full-title></periodical><pages>80-87</pages><volume>1</volume><number>2</number><dates><year>2013</year></dates><isbn>2095-6339</isbn><urls></urls></record></Cite></EndNote>(Mainuri and Owino, 2013).

3.1.4 Experimental Set up and Data AcquisitionThe experimental plots layout will be as shown in figure 3.2. the layout consists of the supply, mainline, sub-mainline and the drip-lines.

Figure 3. SEQ Figure_3. * ARABIC 2 : Experimental plots layout3.1.5 Field experiments
A total area of 150 m2 will be used for the study. Experimental plots 2m by 2m will be usedop. Different treatments will be administered in the plots using factorial experimental design with three replications.

Number of treatments = 12
Number of replications = 3
Total number of plots = 36
Table 3. SEQ Table_3. * ARABIC 1: Treatments and water levelsTreatment no. Irrigation level (%ETc) Mulching system
T1 100 Grass mulch (7,5,3) kg
T2 90 Grass mulch (7,5,3) kg
T3 80 Grass mulch (7,5,3) kg
T4 70 Grass mulch (7,5,3) kg
T5 60 Grass mulch (7,5,3) kg
T6 50 Grass mulch (7,5,3) kg
T7 100 No mulch
T8 90 No mulch
T9 80 No mulch
T10 70 No mulch
T11 60 No mulch
T12 50 No mulch
Tomato is to be planted in single rows of 50-cm space, each having 4 plants of 40cm spacing in between rows ADDIN EN.CITE <EndNote><Cite><Author>Kirimi</Author><Year>2011</Year><RecNum>92</RecNum><DisplayText>(Kirimi<style face=”italic”> et al.</style>, 2011)</DisplayText><record><rec-number>92</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>92</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Kirimi, JK</author><author>Itulya, FM</author><author>Mwaja, VN</author></authors></contributors><titles><title>Effects of nitrogen and spacing on fruit yield of tomato</title><secondary-title>African Journal of Horticultural Science</secondary-title></titles><periodical><full-title>African Journal of Horticultural Science</full-title></periodical><volume>5</volume><dates><year>2011</year></dates><isbn>1998-9326</isbn><urls></urls></record></Cite></EndNote>(Kirimi et al., 2011). One type of mulch (grass) of different densities and six levels of deficit irrigation levels will be used which are 100% ETc, 90% ETc, 80% ETc, 70% ETc, 60%ETc and 50%ETc.

3.1.5 Land preparation, Seedbed preparation and transplantingA seedbed will be prepared and tomato seeds sown. After 30 – 40 days the seedlings will be transplanted to the experimental plots. The experimental site will be ploughed using a jembe and harrowed using a hoe and a rake. After the preparation grass mulch will be applied to the appropriate plots at 5kgm-2 ADDIN EN.CITE <EndNote><Cite><Author>Kader</Author><Year>2017</Year><RecNum>103</RecNum><DisplayText>(Kader<style face=”italic”> et al.</style>, 2017)</DisplayText><record><rec-number>103</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>103</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Kader, Mohammad Abdul</author><author>Senge, Masateru</author><author>Mojid, Mohammad Abdul</author><author>Nakamura, Kimihito</author></authors></contributors><titles><title>Mulching type-induced soil moisture and temperature regimes and water use efficiency of soybean under rain-fed condition in central Japan</title><secondary-title>International Soil and Water Conservation Research</secondary-title></titles><periodical><full-title>International Soil and Water Conservation Research</full-title></periodical><pages>302-308</pages><volume>5</volume><number>4</number><dates><year>2017</year></dates><isbn>2095-6339</isbn><urls></urls></record></Cite></EndNote>(Kader et al., 2017).

3.1.6 Drip Irrigation System LayoutThe mainline will be made of PVC of internal diameter 60mm. The sub mainline will be made of PVC of internal diameter 40mm. The lateral line will be made of PVC of internal diameter 20mm and spacing of laterals will be 0.66 m. The spacing of emitters along the lateral will be 0.50 m ADDIN EN.CITE <EndNote><Cite><Author>Arshad</Author><Year>2014</Year><RecNum>86</RecNum><DisplayText>(Arshad<style face=”italic”> et al.</style>, 2014)</DisplayText><record><rec-number>86</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>86</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Arshad, Imran</author><author>Savona, Paolo</author><author>Khan, Zaheer Ahmed</author></authors></contributors><titles><title>Analysis of Trickle/Drip Irrigation Uniformity by IRRIPRO Simulations</title><secondary-title>International Journal of Research (IJR)</secondary-title></titles><periodical><full-title>International Journal of Research (IJR)</full-title></periodical><pages>635-649</pages><volume>1</volume><number>8</number><dates><year>2014</year></dates><urls></urls></record></Cite></EndNote>(Arshad et al., 2014). A 1000 litre tank will be raised at a height of 1m above the ground for supplying water to the experimental plots through the mainline, sub mainlines and the laterals.

3.1.7 Uniformity Coefficient
The uniformity coefficient considers the major important factor in the uniformity of water application and measures the variation of emitter flow in a drip irrigation system ADDIN EN.CITE <EndNote><Cite><Author>Mohammed</Author><Year>2017</Year><RecNum>113</RecNum><DisplayText>(Mohammed, 2017)</DisplayText><record><rec-number>113</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>113</key></foreign-keys><ref-type name=”Thesis”>32</ref-type><contributors><authors><author>Mohammed, Afnan Babiker Khalil Mahmoud</author></authors></contributors><titles><title>Evaluation Of Hydraulic Performance Of Drip Irrigation System Under Khartoum State Conditions</title></titles><dates><year>2017</year></dates><publisher>University of Khartoum</publisher><urls></urls></record></Cite></EndNote>(Mohammed, 2017). The coefficient is expressed as;
(3.1)
Where,
UC = coefficient of uniformity (%)
D = average of the absolute values of the deviation from the mean discharge (m3/s)
D (3.2)
M = average of discharge values (m3/s)
M (3.3)
Xi = emitter discharge (m3/s)
n = number of observed discharge values (dimensionless)
3.2 Estimation of Tomato Crop Water RequirementThe crop water requirement of tomato for Njoro Sub County will be estimated using the function below;
(3.4)
Where,
ETC = Crop evapotranspiration (mm day-1)
ETo = Reference evapotranspiration (mm day-1)
Kc = Crop coefficient (dimensionless)
3.2.1 Estimation of Reference Evapotranspiration (ETo)Reference Evapotranspiration is the evapotranspiration from a hypothetical grass reference crop with an assumed crop height of 0.12 m, a fixed surface resistance of 70 s/m and an albedo of 0.23. The reference evapotranspiration (ETO) will be estimated using Blaney – Criddle and Hargreaves methods defined by Equations 2.2 in section 2.5.2 and 2.3 in section 2.5.3 respectively.
The mean, maximum and minimum air temperature and latitude data for ten years will be obtained from the Egerton University weather station. The percentage of total daytime hours, monthly consumptive use coefficient, No. of the day in the year between 1 (1stJanuary) and 365 or 366 (31st December) and Solar declination for the study area will be estimated using the available information.

3.2.2 Estimation of Crop Coefficient
Crop coefficient is an estimate of consumptive water use by crops based on evapotranspiration values. Crop coefficient incorporates crop characteristics and averaged effects of evaporation from the soil. There are tabulated typical values for Kc ini, Kc mid and Kc end for various agricultural crops in which the tomato crop coefficient (kc) will be estimated from table 2 in the appendices. The crop evapotranspiration will then be estimated from the reference evapotranspiration and the crop coefficient values evaluated.

3.3 Determination of Tomato Water ProductivityThe tomato water productivity will be evaluated using the water use efficiency.

3.3.1 Water Use EfficiencyThe water productivity will be evaluated by the Water use efficiency (WUE) ADDIN EN.CITE <EndNote><Cite><Author>Payero</Author><Year>2008</Year><RecNum>73</RecNum><DisplayText>(Payero<style face=”italic”> et al.</style>, 2008)</DisplayText><record><rec-number>73</rec-number><foreign-keys><key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″>73</key></foreign-keys><ref-type name=”Journal Article”>17</ref-type><contributors><authors><author>Payero, José O</author><author>Tarkalson, David D</author><author>Irmak, Suat</author><author>Davison, Don</author><author>Petersen, James L</author></authors></contributors><titles><title>Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate</title><secondary-title>Agricultural water management</secondary-title></titles><periodical><full-title>Agricultural water management</full-title></periodical><pages>895-908</pages><volume>95</volume><number>8</number><dates><year>2008</year></dates><isbn>0378-3774</isbn><urls></urls></record></Cite></EndNote>(Payero et al., 2008).
The water use efficiency based on the biomass will be evaluated from the expression:

Where,
= Water use efficiency (kg of biomass/m3of water)
= Total biomass after n weeks of transplanting (kg)
= Irrigation water use at time n
The water use efficiency based on the tomato yield will be evaluated using the expression below:
(3.5)

Where,
= Water use efficiency (kg/m3)
= Total yield (kg/m2)
= Irrigation water use (m3/m2)
Tomato fruits will be harvested at an interval of one week from the maturity period to the end of harvest period. Tomatoes will be weighed after every harvest and the readings recorded. The total weight will then be determined at the end of the harvesting period and the total yield expressed in kg/ha. The yield from each treatment will be determined for estimation of the water productivity.

The total irrigation water use will be determined considering the water application levels in the different plots. The total irrigation water use in the different water levels will be evaluated as;
(3.6)
Where,
= Total Water Use (mm/day)
= Reference evapotranspiration (mm/day)
= crop coefficient (dimensionless)
= Irrigation level (dimensionless)
The total water use at every irrigation level will be;
At 100% ETc, TWU = ETO * Kc * 1
At 90% ETc, TWU = ETO * Kc * 0.9
At 80% ETc, TWU = ETO * Kc * 0.8
At 70% ETc, TWU = ETO * Kc * 0.7
At 60% ETc, TWU = ETO * Kc * 0.6
At 50% ETc, TWU = ETO * Kc * 0.5
The water use efficiency at every water level will then be calculated to determine the water productivity at each level.

3.3.2 Crop Coefficient (kc)The crop coefficient is the ratio of the actual crop evapotranspiration (ETc) to reference crop evapotranspiration (ETo) and it integrates the effects of characteristics that distinguish field crops from grass, like ground cover, canopy properties and aerodynamic resistance. The crop coefficient (Kc) takes into account the crop type and crop development to adjust the ETo for that specific crop. There may be several crop coefficients used for a single crop throughout an irrigation season depending on the crop’s stage of development. Crop growth periods will be divided into four distinct growth stages; initial, crop development, mid-season and late season ADDIN EN.CITE ;EndNote;;Cite;;Author;Lazzara;/Author;;Year;2010;/Year;;RecNum;90;/RecNum;;DisplayText;(Lazzara and Rana, 2010);/DisplayText;;record;;rec-number;90;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;90;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Lazzara, Paola;/author;;author;Rana, Gianfranco;/author;;/authors;;/contributors;;titles;;title;The crop coefficient (kc) values of the major crops grown under Mediterranean climate;/title;;secondary-title;Mediterranean Dialogue on Integrated Water Management, FP6 INCO-MED Funded Project;/secondary-title;;/titles;;periodical;;full-title;Mediterranean Dialogue on Integrated Water Management, FP6 INCO-MED Funded Project;/full-title;;/periodical;;dates;;year;2010;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Lazzara and Rana, 2010). The crop coefficients at the different growth stages will be estimated from the relation;
(3.7)
Where,
kc = Crop coefficient (dimensionless)
wp = width of plant canopy (cm)
wb = bed spacing (cm)
The width of the plant canopy and the bed spacing will be measured using a tape measure at the different growth stages of the tomato.

3.3.3 Irrigation Water RequirementThe irrigation water need of a certain crop is the difference between the crop water need and that part of the rainfall which can be used by the crop (the effective rainfall) ADDIN EN.CITE ;EndNote;;Cite;;Author;Brouwer;/Author;;Year;1986;/Year;;RecNum;93;/RecNum;;DisplayText;(Brouwer and Heibloem, 1986);/DisplayText;;record;;rec-number;93;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;93;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Brouwer, C;/author;;author;Heibloem, M;/author;;/authors;;/contributors;;titles;;title;Irrigation water management: irrigation water needs;/title;;secondary-title;Training manual;/secondary-title;;/titles;;periodical;;full-title;Training manual;/full-title;;/periodical;;volume;3;/volume;;dates;;year;1986;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Brouwer and Heibloem, 1986). It is expressed as;
(3.8)
Where,
IWR = irrigation water requirement (mm)
ETc = crop water requirement (mm)
Pe = effective rainfall (mm)
The effective rainfall will be estimated using rainfall data from table 3.2 in the appendices.

3.4 Estimation of CWR of Tomato using AQUA Crop Model The FAO developed Aqua Crop as the new approach in modelling crop water productivity. The reference evapotranspiration and crop water requirement will be estimated by the AQUA Crop model with the input data to the model being climatic, soil and crop data. The AQUA Crop model input and output are summarized in Table 3.1 below.

Table 3. SEQ Table_3. * ARABIC 2: The Aqua Crop model input data and model outputSoil data Climatic data Crop data Model output
Saturated hydraulic conductivity
Daily rainfall Plant density
Crop productivity
Volumetric water content at saturation
Maximum and minimum air temperature Yield
Crop water requirements
Volumetric water content at saturation
Relative humidity Biomass
Permanent wilting point
Sunshine duration Harvest index
Soil texture analysis
Wind speed Effective rooting depth
Co2 concentration Flowering and maturity time
Green canopy cover
3.4.1 Soil DataDouble ring infiltrometer method will be used to determine the hydraulic conductivity in the field experimental site ADDIN EN.CITE ;EndNote;;Cite;;Author;Pettyjohn;/Author;;Year;2014;/Year;;RecNum;114;/RecNum;;DisplayText;(Pettyjohn, 2014);/DisplayText;;record;;rec-number;114;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;114;/key;;/foreign-keys;;ref-type name=”Thesis”;32;/ref-type;;contributors;;authors;;author;Pettyjohn, William Randall;/author;;/authors;;/contributors;;titles;;title;Infiltration rate and hydraulic conductivity of sand-silt soils in the Piedmont physiographic region;/title;;/titles;;dates;;year;2014;/year;;/dates;;publisher;Georgia Institute of Technology;/publisher;;urls;;/urls;;/record;;/Cite;;/EndNote;(Pettyjohn, 2014). Volumetric water content at saturation of a soil sample is equal to the porosity of the soil. Porosity will be estimated from the relation;
(3.9)Where,
n = Porosity (Ratio)
= Bulk density (g/cm3)
= Particle density (g/cm3)
The bulk density of the soil will be determined using the core method. A soil sample will be oven dried at 105oC after determining its volume ADDIN EN.CITE ;EndNote;;Cite;;Author;Grossman;/Author;;Year;2002;/Year;;RecNum;65;/RecNum;;DisplayText;(Grossman and Reinsch, 2002);/DisplayText;;record;;rec-number;65;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;65;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Grossman, RB;/author;;author;Reinsch, TG;/author;;/authors;;/contributors;;titles;;title;2.1 Bulk density and linear extensibility;/title;;secondary-title;Methods of soil analysis: part 4 physical methods;/secondary-title;;/titles;;periodical;;full-title;Methods of soil analysis: part 4 physical methods;/full-title;;/periodical;;pages;201-228;/pages;;number;methodsofsoilan4;/number;;dates;;year;2002;/year;;/dates;;isbn;0891188932;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Grossman and Reinsch, 2002). The bulk density will then be calculated using the relation;
(3.10)
Where,
?b = Bulk density (g/cm3)
ms = Mass of dry soil (g)
vs = Volume of soil (cm3)
The particle density of soil is estimated to be 2.66g/cm3
Field capacity will be determined in the laboratory using pressure plate apparatus at 1/3 atmospheric pressure for soil samples obtained from different plots ADDIN EN.CITE ;EndNote;;Cite;;Author;Cresswell;/Author;;Year;2008;/Year;;RecNum;74;/RecNum;;DisplayText;(Cresswell;style face=”italic”; et al.;/style;, 2008);/DisplayText;;record;;rec-number;74;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;74;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Cresswell, HP;/author;;author;Green, TW;/author;;author;McKenzie, NJ;/author;;/authors;;/contributors;;titles;;title;The adequacy of pressure plate apparatus for determining soil water retention;/title;;secondary-title;Soil Science Society of America Journal;/secondary-title;;/titles;;periodical;;full-title;Soil Science Society of America Journal;/full-title;;/periodical;;pages;41-49;/pages;;volume;72;/volume;;number;1;/number;;dates;;year;2008;/year;;/dates;;isbn;1435-0661;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Cresswell et al., 2008). The permanent wilting point of the soil samples will be determined in the laboratory by the pressure plate equipment ADDIN EN.CITE ;EndNote;;Cite;;Author;Romano;/Author;;Year;2002;/Year;;RecNum;69;/RecNum;;DisplayText;(Romano and Santini, 2002);/DisplayText;;record;;rec-number;69;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;69;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Romano, Nunzio;/author;;author;Santini, Alessandro;/author;;/authors;;/contributors;;titles;;title;3.3. 3 Field;/title;;secondary-title;Methods of Soil Analysis: Part 4 Physical Methods;/secondary-title;;/titles;;periodical;;full-title;Methods of soil analysis: part 4 physical methods;/full-title;;/periodical;;pages;721-738;/pages;;number;methodsofsoilan4;/number;;dates;;year;2002;/year;;/dates;;isbn;0891188932;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Romano and Santini, 2002). Hydrometer method of soil texture analysis will be used and soil samples from different plots will be analyzed ADDIN EN.CITE ;EndNote;;Cite;;Author;Gee;/Author;;Year;2002;/Year;;RecNum;72;/RecNum;;DisplayText;(Gee and Or, 2002);/DisplayText;;record;;rec-number;72;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;72;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Gee, Glendon W;/author;;author;Or, Dani;/author;;/authors;;/contributors;;titles;;title;2.4 Particle-size analysis;/title;;secondary-title;Methods of soil analysis. Part;/secondary-title;;/titles;;periodical;;full-title;Methods of soil analysis. Part;/full-title;;/periodical;;pages;255-293;/pages;;volume;4;/volume;;number;598;/number;;dates;;year;2002;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Gee and Or, 2002).
3.4.2 Climatic dataThe climatic data in Table 3.1 will be obtained from the Egerton University weather station for the growing period of the tomato.

3.4.3 Crop ParametersThe plant density of a certain bed of plants is described by the number of plants within a given unit of area. This will be carried out by counting the number of plants per plot and dividing by the area of the plot. The fruit yield per hectare will be determined by weighing the fruits harvested weekly from the field using a weighing balance and adding to obtain the total yield. Biomass is the total quantity or weight of organisms in a given area or volume. This will be done by weighing the tomato crop per plot and dividing by the area of the plot. Harvest index is the weight of the harvested product as a percentage of the total plant weight of the tomato. This will be done weighing the fruits harvested in the field and dividing by the total weight of the crop in the field. Effective rooting depth is the depth of soil used by the main body of the plant roots to obtain most of the stored moisture and plant food under proper irrigation. This will be done by uprooting and measuring the rooting depth of the crop. Flowering and maturity time will be estimated in terms of days from planting date to flowering and maturity dates respectively. Green canopy cover is the aboveground portion of a plant community or crop, formed by the collection of individual plant crowns. Crop germination is the period of the tomato germination in days and will be determined from the sowing time to germination time.
3.5 Irrigation optimality relative to water delivery and application schemes under different water management regimes
3.5 Statistical AnalysisThe performance of the AQUA Crop model will be evaluated using the following statistical parameters; Root Mean Square Error and Nash and Sutcliffe Efficiency ADDIN EN.CITE ;EndNote;;Cite;;Author;Heng;/Author;;Year;2009;/Year;;RecNum;88;/RecNum;;DisplayText;(Heng;style face=”italic”; et al.;/style;, 2009);/DisplayText;;record;;rec-number;88;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;88;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Heng, Lee Kheng;/author;;author;Hsiao, Theodore;/author;;author;Evett, Steve;/author;;author;Howell, Terry;/author;;author;Steduto, Pasquale;/author;;/authors;;/contributors;;titles;;title;Validating the FAO AquaCrop model for irrigated and water deficient field maize;/title;;secondary-title;Agronomy Journal;/secondary-title;;/titles;;periodical;;full-title;Agronomy Journal;/full-title;;/periodical;;pages;488-498;/pages;;volume;101;/volume;;number;3;/number;;dates;;year;2009;/year;;/dates;;isbn;1435-0645;/isbn;;urls;;/urls;;/record;;/Cite;;/EndNote;(Heng et al., 2009).

3.5.1 Root Mean Square Error (RMSE)The RMSE is expressed as;
(3.11)
3.5.2 Nash and Sutcliffe Efficiency (NSE)
Nash and Sutcliffe Efficiency is a normalized statistic that determines the relative magnitude of the residual compared to the measured data variance. NSE ranges between ?? and 1.0 (1 inclusive), with NSE = 1 being the optimal value. Values between 0.0 and 1.0 are generally viewed as acceptable levels of performance, whereas values ;0.0 indicates that the mean observed value is a better predictor than the simulated value, which indicates unacceptable performance. The Nash and Sutcliffe efficiency is expressed as;
(3.12)
Where,
Si = simulated values
Oi = observed (measured) values
= mean value of Oi N = number of observations
NSE ranges between ?? and 1.0 (1 inclusive), with NSE = 1 being the optimal value. Values between 0.0 and 1.0 are generally viewed as acceptable levels of performance, whereas values ? 0.0 indicates that the mean observed value is a better predictor than the simulated value, which indicates unacceptable performance ADDIN EN.CITE ;EndNote;;Cite;;Author;Moriasi;/Author;;Year;2007;/Year;;RecNum;87;/RecNum;;DisplayText;(Moriasi;style face=”italic”; et al.;/style;, 2007);/DisplayText;;record;;rec-number;87;/rec-number;;foreign-keys;;key app=”EN” db-id=”rpd09pppmft2e1eetx25zfr7faxxz0prrz02″;87;/key;;/foreign-keys;;ref-type name=”Journal Article”;17;/ref-type;;contributors;;authors;;author;Moriasi, Daniel N;/author;;author;Arnold, Jeffrey G;/author;;author;Van Liew, Michael W;/author;;author;Bingner, Ronald L;/author;;author;Harmel, R Daren;/author;;author;Veith, Tamie L;/author;;/authors;;/contributors;;titles;;title;Model evaluation guidelines for systematic quantification of accuracy in watershed simulations;/title;;secondary-title;Transactions of the ASABE;/secondary-title;;/titles;;periodical;;full-title;Transactions of the ASABE;/full-title;;/periodical;;pages;885-900;/pages;;volume;50;/volume;;number;3;/number;;dates;;year;2007;/year;;/dates;;urls;;/urls;;/record;;/Cite;;/EndNote;(Moriasi et al., 2007).

3.6 Expected ResultsEstimated crop water requirement at different growth stages for tomato in Njoro Sub County.

Water use efficiency and optimal tomato water requirement for Njoro Sub County under limited water use.

CWR based on calibrated AQUA Crop model for Njoro Sub County.

4.0 WORK PLANACTIVITY DURATION Year 2018 2019 Month Mar Apr Ma Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Proposal writing Proposal defense(Dep. and Faculty) and Correction Reconnaissance and acquisition of equipment Data collection Data compilation Data analysis Thesis compilation and defense Thesis correction and submission
5.0 BUDGETS/NO ITEMS UNIT COST (KES) NUMBER OF UNITS TOTAL COST (KES)
1 Soil sampling and analysis 1000 30 30000
2 Experimental set up lump sum lump sum 155000
3 Subsistence for field work 1000 60 60000
4 Research assistant 1000 60 60000
6 Publication of journal papers 20000 2 40000
7 Internet services 1000 10 10000
8 Printing and lamination 1500 10 15000
Total 400000

REFERENCES ADDIN EN.REFLIST Abbaspour, K. C., Faramarzi, M., Ghasemi, S. S., and Yang, H. (2009). Assessing the impact of climate change on water resources in Iran. Water resources research, 45(10). Ahaneku, I. E. (2010). Performance evaluation of portable sprinkler irrigation system in Ilorin, Nigeria. Indian Journal of Science and Technology, 3(8), 853-857. Akay, U. (2015). Optimization of a tool for the choice of an irrigation system based on local parameters. Allen, R. G., Pereira, L. S., Raes, D., and Smith, M. (1998). Crop evapotranspiration-Guidelines for computing crop water requirements-FAO Irrigation and drainage paper 56. FAO, Rome, 300(9), D05109. Amare, H., Asfaw, K., and Kassahun, A. (2017). Evaluation of Deficit Irrigation and Mulching on Water Productivity of Tomato (Lycopersicon esculentum Mill) Under Drip Irrigation System at Kallu Woreda, South Wollo, Ethiopia. Harmaya University. Arshad, I., Savona, P., and Khan, Z. A. (2014). Analysis of Trickle/Drip Irrigation Uniformity by IRRIPRO Simulations. International Journal of Research (IJR), 1(8), 635-649. Ayyogari, K., Sidhya, P., and Pandit, M. (2014). Impact of climate change on vegetable cultivation-a review. International Journal of Agriculture, Environment and Biotechnology, 7(1), 145. Bamohuni, S. (2011). Design proposal of drip irrigation system for an efficient management of irrigation water for maize improved seeds production in a part of seeds farm of loumbila. Universita degli Studi di Firenze Facolta di Agraria, 33-40. Birhanu, K., and Tilahun, K. (2010). Fruit yield and quality of drip-irrigated tomato under deficit irrigation. African Journal of Food, Agriculture, Nutrition and Development, 10(2). Bouraima, A.-K., Weihua, Z., and Chaofu, W. (2015). Irrigation water requirements of rice using Cropwat model in Northern Benin. International Journal of Agricultural and Biological Engineering, 8(2), 58. Brouwer, C., and Heibloem, M. (1986). Irrigation water management: irrigation water needs. Training manual, 3. Cresswell, H., Green, T., and McKenzie, N. (2008). The adequacy of pressure plate apparatus for determining soil water retention. Soil Science Society of America Journal, 72(1), 41-49. Darko, R. O., Shouqi, Y., Haofang, Y., Liu, J., and Abbey, A. (2016). Calibration and validation of AquaCrop for deficit and full irrigation of tomato. International Journal of Agricultural and Biological Engineering, 9(3), 104-110. De Silva, C., Weatherhead, E., Knox, J. W., and Rodriguez-Diaz, J. (2007). Predicting the impacts of climate change—A case study of paddy irrigation water requirements in Sri Lanka. Agricultural water management, 93(1-2), 19-29. Evans, R. G., and Sadler, E. J. (2008). Methods and technologies to improve efficiency of water use. Water resources research, 44(7). Fereres, E., and Soriano, M. A. (2006). Deficit irrigation for reducing agricultural water use. Journal of experimental botany, 58(2), 147-159. Gee, G. W., and Or, D. (2002). 2.4 Particle-size analysis. Methods of soil analysis. Part, 4(598), 255-293. George, B. A., and Raghuwanshi, N. (2012). Inter-comparison of reference evapotranspiration estimated using six methods with data from four climatological stations in India. Journal of Indian Water Resources Society, 32(3? 4), 15-22. Grossman, R., and Reinsch, T. (2002). 2.1 Bulk density and linear extensibility. Methods of soil analysis: part 4 physical methods(methodsofsoilan4), 201-228. Haidula, S. (2016). Irrigation water use and vegetable production efficiency assessment between sprinkler and drip irrigation systems at North Central Namibia (NCN):(Study on three vegetable crops: tomato, cabbage, and pepper). Hakala, A., and Pekonen, L. (2008). The Impact of the Irrigation System and Agricultural Production on Water Quality in Chókwé. Heng, L. K., Hsiao, T., Evett, S., Howell, T., and Steduto, P. (2009). Validating the FAO AquaCrop model for irrigated and water deficient field maize. Agronomy Journal, 101(3), 488-498. Jordán, A., Zavala, L. M., and Muñoz-Rojas, M. (2011). Mulching, effects on soil physical properties Encyclopedia of agrophysics (pp. 492-496): Springer.Kader, M. A., Senge, M., Mojid, M. A., and Nakamura, K. (2017). Mulching type-induced soil moisture and temperature regimes and water use efficiency of soybean under rain-fed condition in central Japan. International Soil and Water Conservation Research, 5(4), 302-308. Kang, Y., Khan, S., and Ma, X. (2009). Climate change impacts on crop yield, crop water productivity and food security–A review. Progress in Natural Science, 19(12), 1665-1674. Karanja, F. K. (2006). Cropwat model analysis of crop water use in six districts in Kenya. CEEPA DP35, University of Pretoria, South Africa. Kere, G., Nyanjage, M., Liu, G., and Nyalala, S. (2003). Influence of drip irrigation schedule and mulching materials on yield and quality of greenhouse tomato (Lycopersicon esculentum Mill.’Money Maker’). Asian Journal of Plant Sciences, 2(14), 1052-1058. Keshtgar, A. (2012). Optimum design of drip irrigation system using microtubes as emitters. Kirimi, J., Itulya, F., and Mwaja, V. (2011). Effects of nitrogen and spacing on fruit yield of tomato. African Journal of Horticultural Science, 5. Kögler, F., and Söffker, D. (2017). Water (stress) models and deficit irrigation: System-theoretical description and causality mapping. Ecological Modelling, 361, 135-156. Ku?çu, H., Turhan, A., and Demir, A. O. (2014). The response of processing tomato to deficit irrigation at various phenological stages in a sub-humid environment. Agricultural water management, 133, 92-103. La Pena, R. d., and Hughes, J. (2007). Improving vegetable productivity in a variable and changing climate. Lazzara, P., and Rana, G. (2010). The crop coefficient (kc) values of the major crops grown under Mediterranean climate. Mediterranean Dialogue on Integrated Water Management, FP6 INCO-MED Funded Project. Mainuri, Z. G., and Owino, J. O. (2013). Effects of land use and management on aggregate stability and hydraulic conductivity of soils within River Njoro Watershed in Kenya. International Soil and Water Conservation Research, 1(2), 80-87. Mngumi, J. W. (2016). Perceptions of climate change, environmental variability and the role of agricultural adaptation strategies by small-scale farmers in Africa: the case of Mwanga district in Northern Tanzania. University of Glasgow. Mohammed, A. B. K. M. (2017). Evaluation Of Hydraulic Performance Of Drip Irrigation System Under Khartoum State Conditions. University of Khartoum. Molden, D., Oweis, T., Steduto, P., Bindraban, P., Hanjra, M. A., and Kijne, J. (2010). Improving agricultural water productivity: Between optimism and caution. Agricultural Water Management, 97(4), 528-535. Monte, J. A., Carvalho, D. F. d., Medici, L. O., da Silva, L. D., and Pimentel, C. (2013). Growth analysis and yield of tomato crop under different irrigation depths. Revista Brasileira de Engenharia Agrícola e Ambiental, 17(9), 926-931. Moriasi, D. N., Arnold, J. G., Van Liew, M. W., Bingner, R. L., Harmel, R. D., and Veith, T. L. (2007). Model evaluation guidelines for systematic quantification of accuracy in watershed simulations. Transactions of the ASABE, 50(3), 885-900. Mukherjee, A., Sarkar, S., and Sarkar, A. (2018). Productivity and Profitability of Tomato Due to Irrigation Frequency and Mulch. International Journal of Vegetable Science, 24(1), 43-57. Nasr Azadani, F. (2012). Modeling the impact of climate change on water resources case study: Arkansas River Basin in Colorado. Colorado State University. Libraries. Orang, M. N., Scott Matyac, J., and Snyder, R. L. (2008). Survey of irrigation methods in California in 2001. Journal of Irrigation and Drainage Engineering, 134(1), 96-100. Ortiz, V. (2015). Effects of Different Mulching Techniques for Improving Irrigation Water Use Efficiency and Yields for Cherry Tomato Produced by Del Cabo Farm in Baja California, México: Wageningen University.Payero, J. O., Tarkalson, D. D., Irmak, S., Davison, D., and Petersen, J. L. (2008). Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate. Agricultural water management, 95(8), 895-908. Pettyjohn, W. R. (2014). Infiltration rate and hydraulic conductivity of sand-silt soils in the Piedmont physiographic region. Georgia Institute of Technology. Ramalan, A., Nega, H., and Oyebode, M. (2010). Effect of deficit irrigation and mulch on water use and yield of drip irrigated onions. WIT Transactions on Ecology and the Environment, 134, 39-50. Romano, N., and Santini, A. (2002). 3.3. 3 Field. Methods of soil analysis: part 4 physical methods(methodsofsoilan4), 721-738. Roudier, P., Sultan, B., Quirion, P., and Berg, A. (2011). The impact of future climate change on West African crop yields: What does the recent literature say? Global Environmental Change, 21(3), 1073-1083. Saeed, R., and Ahmad, R. (2009). Vegetative growth and yield of tomato as affected by the application of organic mulch and gypsum under saline rhizosphere. Pak. J. Bot, 41(6), 3093-3105. Salemi, H., Soom, M. A. M., Lee, T. S., Mousavi, S. F., Ganji, A., and Yusoff, M. K. (2011). Application of AquaCrop model in deficit irrigation management of winter wheat in arid region. African Journal of Agricultural Research, 6(10), 2204-2215. Salokhe, V., Babel, M., and Tantau, H. (2005). Water requirement of drip irrigated tomatoes grown in greenhouse in tropical environment. Agricultural water management, 71(3), 225-242. Savva, A. P., and Frenken, K. (2002). Crop water requirements and irrigation scheduling: FAO Sub-Regional Office for East and Southern Africa Harare.Sentelhas, P. C., Gillespie, T. J., and Santos, E. A. (2010). Evaluation of FAO Penman–Monteith and alternative methods for estimating reference evapotranspiration with missing data in Southern Ontario, Canada. Agricultural water management, 97(5), 635-644. Singh, D. (2016). Growth, yield and quality of chilli (Capsicum annuum L.) in relation to use of various types of mulches. Punjab Agricultural University, Ludhiana. Talaee, P. H. (2014). Performance evaluation of modified versions of Hargreaves equation across a wide range of Iranian climates. Meteorology and Atmospheric Physics, 126(1-2), 65-70. Teklu, L. (2016). Effect of Furrow Irrigation Methods Under Deficit Irrigation on Growth, Yield and Water Productivity of Tomato (Solanum Lycopersicum L.) at Dugda District, East Shewa Zone, Eastern Oromia, Ethiopia. Haramaya University. Wachira, J. M. (2012). Comparative analysis of greenhouse versus open-field small-scale tomato production in Nakuru-North District, Kenya. Xu, C.-Y., and Singh, V. (2002). Cross comparison of empirical equations for calculating potential evapotranspiration with data from Switzerland. Water Resources Management, 16(3), 197-219. Yaghi, T., Arslan, A., and Naoum, F. (2013). Cucumber (Cucumis sativus, L.) water use efficiency (WUE) under plastic mulch and drip irrigation. Agricultural Water Management, 128, 149-157.

APPENDICES
Plate 2.1: sprinkler irrigation system

Plate 2.2: Furrow irrigation system layout

Plate 2.3: Drip irrigation layout
Table 1. SEQ Table_1. * ARABIC 1 Mean daily percentage (p) of annual day time hours for different latitudes
Table 1. SEQ Table_1. * ARABIC 2 Crop coefficients for specific crops
Table 3.2: Rainfall and effective rainfall

x

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