Management of Water Use in Agriculture

I Water Resources and Water Quality.- 1 Global Water Resources and Agricultural Use.- 1.1 Introduction.- 1.2 Global and Continental Water Resources.- 1.2.1 World Water Cycle and Budget.- 1.2.2 Continental Water Resources.- 1.2.3 Global Water Uses.- 1.3 Agricultural Uses of Water.- 1.3.1 United States Agricultural Water Uses.- 1.3.2 United States Irrigation Budget.- 1.3.3 Global Agricultural Water Uses.- 1.4 Anticipated Impacts on Future Agricultural Water Use.- 1.4.1 Competition for Water Quantity and Quality from Other Sectors.- 1.4.2 Increasing Regulation on Agricultural Waters.- 1.4.3 Ecological Impacts.- 1.5 Strategies for the Future.- 1.5.1 New Water Supplies.- 1.5.2 Water Conservation.- 1.5.3 Better Use of Rainwater.- 1.5.4 Institutional and Policy Changes.- 1.6 Summary and Conclusions.- References.- 2 Water Suitability for Agriculture.- 2.1 Introduction.- 2.2 Water Quality - Origin Dependence.- 2.2.1 Natural Origin.- 2.2.2 Man’s Activities as the Origin.- 2.3 Quality Parameters Relevant to Crop Production.- 2.3.1 Salinity.- 2.3.2 Acidity-Alkalinity.- 2.3.3 Specific Ion Effect.- 2.3.4 The Effect of Micropollutants.- 2.4 Quality Parameters Relevant to Animal Production.- 2.4.1 Chemical Parameters.- 2.4.2 Biological Parameters.- 2.5 Water Quality - Soil Quality Relationship.- 2.5.1 Soils.- 2.5.1.1 Salts.- 2.5.1.2 Trace Elements.- 2.5.1.3 Organic Micropollutants.- 2.5.2 Soil Hydraulic Properties.- 2.5.2.1 Salinity - Alkalinity Effect.- 2.5.2.2 Effects of Suspended Particles.- 2.5.3 Soil Microflora.- References.- II Water Conservation and Technology.- 3 Crop Irrigation.- 3.1 Crop Water Status and Its Components.- 3.2 Evapotranspiration and Crop Water Requirement.- 3.2.1 Direct Methods.- 3.2.2 Indirect Methods.- 3.3 Irrigation Timing.- 3.3.1 Soil Moisture Content.- 3.3.2 Soil Water Tension.- 3.3.3 Evapotranspiration Rate.- 3.3.4 Plant Parameters.- 3.4 Implication of Irrigation Method on Scheduling.- 3.4.1 Surface Irrigation.- 3.4.2 Sprinkler Irrigation.- 3.4.3 Trickle and Drip Irrigation.- 3.5 Effect of Crop Growth Stage on Irrigation Practices.- 3.5.1 Vegetative Growth.- 3.5.2 Flowering.- 3.5.3 Fruit Development.- 3.5.4 Irrigation at Different Growth Stages Under Limited Irrigation Water.- 3.6 Irrigation Management in Humid Areas.- References.- 4 Irrigation Techniques and Evaluations.- 4.1 Introduction.- 4.1.1 Farm Irrigation Methods.- 4.1.2 Definitions of Efficiency and Uniformity.- 4.1.3 Project or River Basin Considerations.- 4.2 Surface Irrigation.- 4.2.1 Classification of Types.- 4.2.2 Conditions of Applicability.- 4.2.3 Practices.- 4.2.4 Constraints to Adoption.- 4.2.4.1 Constraint to Efficient Use of Water.- 4.2.5 Evaluation Methods.- 4.3 Sprinkler Irrigation.- 4.3.1 Classification of Types.- 4.3.1.1 Fixed Sprinklers.- 4.3.1.2 Continuous-Move Sprinklers.- 4.3.1.3 Types of Sprinkler Outlets and Nozzles.- 4.3.2 Conditions of Applicability.- 4.3.3 Practices.- 4.3.4 Constraints to Adoption.- 4.3.4.1 Constraints to Efficient Use of Water.- 4.3.5 Evaluation Methods.- 4.4 Micro-irrigation.- 4.4.1 Classification of Types.- 4.4.2 Conditions of Applicability.- 4.4.3 Practices.- 4.4.4 Constraints to Adoption.- 4.4.4.1 Constraints to Efficient Use of Water.- 4.4.5 Evaluation Methods.- 4.5 Considerations in Irrigation Method Selection.- References.- 5 Drainage and Subsurface Water Management.- 5.1 Introduction.- 5.2 Drainage Requirements.- 5.2.1 Trafficability.- 5.2.2 Protection from Excessive Soil Water Conditions.- 5.2.3 Salinity Control.- 5.2.4 Limiting Factors and Constraints.- 5.3 Subirrigation.- 5.4 Design and Analysis of Drainage Systems.- 5.4.1 Drainage Methods.- 5.4.2 Drainage Theory and Simulation Models.- 5.5 Simulation Analyses.- 5.5.1 Drainage.- 5.5.2 Subirrigation.- 5.6 Economic Analyses.- 5.7 Off-Site Impacts.- References.- 6 Runoff Irrigation.- 6.1 Introduction.- 6.2 Present Development and Expansion of Runoff Irrigation.- 6.3 Generation of Runoff.- 6.3.1 General Principles.- 6.3.2 Rainfall Simulators.- 6.3.3 Runoff as a Result of Crust Formation.- 6.3.4 Physical Models of Runoff Formation in Crusting Soils.- 6.4 Modeling Watershed Runoff Production.- 6.4.1 Microcatchment Water Harvesting.- 6.4.2 Modeling Rainfall Runoff Relationships for an SCWH Element.- 6.4.3 The Role of PAC in Water Harvesting.- 6.5 Runoff Irrigation and Remote Sensing.- 6.6 Agricultural Use of Runoff Water.- 6.6.1 Engineering Description of Water Harvesting Systems.- 6.6.1.1 Microcatchment Water Harvesting.- 6.6.1.2 Small Catchment Water Harvesting.- 6.6.1.3 Comparison of MCWH and SCWH Systems.- 6.6.2 Agroforestry.- 6.7 Concluding Remarks.- References.- 7 Efficient Use of Water in Rain-Fed Agriculture.- 7.1 Introduction.- 7.1.1 Definitions.- 7.1.1.1 Rain-Fed vs. Dryland Agriculture.- 7.1.1.2 Water Use Efficiency.- 7.1.2 Objectives of Dryland Farming.- 7.1.2.1 Subsistence Farmers.- 7.1.2.2 Farmers in a Market Economy.- 7.1.2.3 National Economy (Institutional Interest).- 7.1.3 The Relation Between Yield Production Objectives and Water Supply to Crops.- 7.1.3.1 The Yield Response Curve.- 7.1.3.2 Water Use Efficiency vs. Water Use.- 7.1.3.3 Yield vs. Water Use Efficiency.- 7.1.3.4 The Effects of Increasing or Decreasing Consumptive Use (CU).- 7.1.4. Constraints to Efficient Water Use.- 7.1.4.1 Climatic Constraints.- 7.1.4.2 Soil Physical Properties.- 7.1.4.3 Soil Salinity.- 7.1.4.4 Fertility and Nutrient Availability.- 7.1.4.5 Weeds.- 7.1.4.6 Pests and Diseases.- 7.2 Options for Improving Water Use Efficiency.- 7.2.1 Increase the Nominator of the Water Use Efficiency.- 7.2.2 Decrease Denominator of Water Use Efficiency - Water Conservation.- 7.2.2.1 Eliminate Runoff Losses.- 7.2.2.2 Decreasing Evaporation Losses.- 7.2.2.3 Limiting Deep Drainage.- 7.2.2.4 Use of Anti-Transpirants.- 7.3 Integrated Strategies for Efficient Water Use - Farming Systems.- 7.3.1 Conservation Tillage.- 7.3.1.1 Contour Cultivation and Strip Cropping.- 7.3.1.2 Modifying Soil Surface Micro-Relief to Increase Retention.- 7.3.1.3 Various Unconventional Tillage Principles and Implements.- 7.3.1.4 Major Land Shaping for Runoff Control.- 7.3.1.5 Residue Management.- 7.3.2 Crop Rotations Including Fallow Periods.- 7.3.3 Conjunctive Use of Rainfall and Irrigation.- 7.3.4 Runoff Farming.- 7.4 Concluding Remarks.- References.- III Problem Water Uses and Treatment.- 8 Irrigation with Saline Water.- 8.1 Introduction.- 8.2 Potential for Using Saline Water for Irrigation.- 8.2.1 Historical Evidence.- 8.2.2 Limitations and Potential Long-Term Effects.- 8.3 Factors that Facilitate the Use of Saline Water.- 8.3.1 Irrigation Water Sources.- 8.3.2 Site Considerations.- 8.3.3 Crop Selection.- 8.4 Management of Saline Water to Optimize Crop Performance.- 8.4.1 Crop Salt-Tolerance Expressions.- 8.4.2 Utilizing a Single Source of Water.- 8.4.3 Utilizing Waters From Multiple Sources of Variable Quality.- 8.4.3.1 Blending Irrigation Water Supplies.- 8.4.4 Cyclic Irrigation Method.- 8.4.5 Blending vs. Cyclic Practices.- 8.5 Conclusions.- References.- 9 Irrigation with Treated Sewage Effluents.- 9.1 Introduction.- 9.2 Need for Preapplication Treatment.- 9.3 Municipal Wastewater (Sewage) Characteristics.- 9.3.1 Wastewater Sources.- 9.3.2 Wastewater Flow Rates.- 9.3.3 Wastewater Constituents and Compositions.- 9.4 Municipal Wastewater Treatment and Effluent Characteristics.- 9.4.1 Preliminary Treatment.- 9.4.2 Primary Treatment.- 9.4.3 Secondary Treatment.- 9.4.3.1 High-Rate Biological Processes.- 9.4.3.2 Low-Rate Biological Processes.- 9.4.3.3 Comparison of High- and Low-Rate Biological Processes.- 9.4.3.4 Tertiary and Advanced Treatment.- 9.4.3.5 Disinfection.- 9.4.3.6 Effluent Storage.- 9.5 Irrigation with Treated Sewage Effluents.- 9.5.1 Irrigation Water Quality Guidelines.- 9.5.2 Irrigation of Vegetable Crops - a 5-Year Field Demonstration Project in Monterey, California.- 9.5.2.1 Description of the Project.- 9.5.2.2 Results of Public Health Studies: Virus Survival.- 9.5.2.3 Results of Agricultural Studies: Irrigation Water Quality.- 9.5.2.4 MWRSA Findings.- 9.6 Health and Safety of Using Reclaimed Wastewater for Irrigation.- 9.6.1 Wastewater Reclamation Criteria in Other Countries.- 9.6.2 Wastewater Irrigation in Developing Countries.- 9.7 Appropriate Technologies for Wastewater Treatment.- 9.7.1 Selection of Appropriate Technologies.- References.- 10 Drainage Water Treatment and Disposal.- 10.1 Introduction.- 10.2 Treatment Technology.- 10.2.1 Objectives.- 10.2.2 Available Technologies.- 10.2.2.1 Desalination.- 10.2.2.2 Biological Processes.- 10.2.2.3 Chemical Treatment.- 10.2.2.4 Physical Treatment.- 10.3 Disposal of Residual Products.- 10.3.1 Disposal.- 10.3.1.1 Surface Waters.- 10.3.1.2 Evaporation Ponds.- 10.3.1.3 Deep-Well Injection.- 10.3.2 Reclamation and Reuse.- 10.4 Integrated Systems.- 10.4.1 Cogeneration-Desalination.- 10.4.2 Solar Gradient Ponds.- 10.5 Summary and Conclusions.- References.- IV Policy and Management Evaluations.- 11 Economics of Non-Uniform Water Infiltration in Irrigated Fields.- 11.1 Introduction.- 11.2 Distribution of Average Yield.- 11.3 Economic Optimization.- 11.3.1 Cost Estimates of Water Distribution Patterns.- 11.4 Empirical Findings and Their Implications.- 11.5 Conclusions and Recommendations for Further Research.- References.- 12 Irrigation Management Under Drought Conditions.- 12.1 Introduction.- 12.1.1 Defining Drought.- 12.1.2 Drought and Water Supply.- 12.1.3 Drought and Water Demand.- 12.1.4 Drought and Water Quality.- 12.2 On-Farm Strategies for Drought Management.- 12.2.1 Short-Term.- 12.2.2 Long-Term.- 12.3 Policy Considerations.- 12.3.1 Competing Uses for Water.- 12.3.2 Value of Water in Alternative Uses.- 12.3.3 Legal and Institutional Constraints.- 12.3.4 Options for Reallocation.- 12.3.5 Risk Tradeoffs in Allocating Stored Water.- 12.4 Modeling Farmer Response to Water Shortage.- 12.5 Contingent Water Markets for Drought Management: The Idaho Case.- 12.5.1 The Idaho Setting and Study Results.- 12.5.2 Legal, Institutional and Physical Considerations.- 12.5.3 Other Applications.- 12.6 Global Climate Change and Western Irrigation.- 12.7 Conclusion.- References.- 13 Evaluation of Management and Policy Issues Related to Irrigation of Agricultural Crops.- 13.1 Introduction.- 13.2 A Crop-Water Production Function Model.- 13.3 Evaluation of Management and Policy Issues.- 13.3.1 Optimal Combination of Fresh and Saline Waters.- 13.3.2 Evaluation and Adoption of Irrigation Technologies.- 13.3.3 On-Farm Management Practices for Drainage and Salinity Problems.- 13.3.4 Taxes and Subsidies for Water Conservation and Pollution Reduction.- 13.3.5 Institutions for Water Conservation and Drainage Reduction.- 13.3.6 Regional Drainage Quality and Quantity Control Policies.- 13.4 Discussion and the Need for Further Development.- References.