[PDF] Crop Yield Response To Deficit Irrigation eBook
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This book discusses general concept and management issues of deficient irrigation practices, covering a wide range of field crops including cotton, maize, soybean, wheat, sugarcane, and the like, based on five years of field research implemented in fourteen different countries, in Latin America, Africa, Europe and Asia. Additionally, guidelines are given for experimental methodology and data analysis for evaluating crop yield response to deficient irrigation. Experimental data, discussions and cited references will be an asset not only to field irrigation engineers but also to research scientists including soil and irrigation scientists and agronomists, for whom the book would be an invaluable reference source.
In the context of improving water productivity, there is a growing interest in deficit irrigation, an irrigation practice whereby water supply is reduced below maximum levels and mild stress is allowed with minimal effects on yield. Under conditions of scarce water supply and drought, deficit irrigation can lead to greater economic gains than maximizing yields per unit of water for a given crop; farmers are more inclined to use water more efficiently, and more water-efficient cash crop selection helps optimize returns. However, this approach requires precise knowledge of crop response to water as drought tolerance varies considerably by species, cultivar and stage of growth. The studies present the latest research concepts and involve various practices for deficit irrigation. Both annual and perennial crops were exposed to different levels of water stress, either during a particular growth phase, throughout the whole growing season or in a combination of growth stages. The overall finding, based on the synthesis of the different contributions, is that deficit or regulated-deficit irrigation can be beneficial where appropriately applied. Substantial savings of water can be achieved with little impact on the quality and quantity of the harvested yield. However, to be successful, an intimate knowledge of crop behavior is required, as crop response to water stress varies considerably.
This report contains a collection of papers from a workshopâ€"Strengthening Science-Based Decision-Making for Sustainable Management of Scarce Water Resources for Agricultural Production, held in Tunisia. Participants, including scientists, decision makers, representatives of non-profit organizations, and a farmer, came from the United States and several countries in North Africa and the Middle East. The papers examined constraints to agricultural production as it relates to water scarcity; focusing on 1) the state of the science regarding water management for agricultural purposes in the Middle East and North Africa 2) how science can be applied to better manage existing water supplies to optimize the domestic production of food and fiber. The cross-cutting themes of the workshop were the elements or principles of science-based decision making, the role of the scientific community in ensuring that science is an integral part of the decision making process, and ways to improve communications between scientists and decision makers.
First title in a major new seriesAddresses improving water productivity to relieve problems of scarcity and competition to provide for food and environmental securityDraws from scientists having a multitude of disciplines to approach this important problemIn a large number of developing countries, policy makers and researchers are increasingly aware of the conflicting demands on water, and look at agriculture to be more effective in its use of water. Focusing on both irrigated and rain-fed agriculture, this book gives a state of the art review of the limits and opportunities for improving water productivity in crop production. It demonstrates how efficiency of water use can be enhanced to maximize yields. The book represents the first in a new series of volumes resulting from the Comprehensive Assessment of Water Management in Agriculture, a research program conducted by the CGIAR's Future Harvest Centres, the Food and Agriculture Organization of the United Nations and partners worldwide. It will be of significant interest to those working in areas of soil and crop science, water management, irrigation, and development studies.
The Handbook of Irrigation System Selection for Semi-Arid Regions compares the various types of available irrigation systems for different regions and conditions, and explains how to analyze field data to determine the suitability of the land for surface, sprinkle, or drip irrigation systems. The book focuses on strategies for irrigation development and management and examines deficit irrigation and partial root-zone drying systems. Also, solute leaching modeling under different irrigation systems, soil moisture conditions, and organic fertilizer application in arid areas are discussed. Further, it examines multi-criteria decision making for irrigation management and the appraisal of agricultural lands for irrigation in hot, sub-humid regions. Features: Presents comparative analysis to aid in the selection of the most appropriate types of irrigation systems according to land characteristics. Includes numerous practical case studies. Offers parametric evaluation systems for irrigation purposes. Considers data from semi-arid zones, each with different sub-climates. Focusing on semi-arid land, the book highlights parametric evaluation systems for irrigation purposes, along with the use of analytical hierarchy processes integrated with GIS to determine which systems are best suited. This comprehensive and well-illustrated handbook will be of great interest to students, professionals, and researchers involved with all aspects of irrigation in semi-arid regions.
Vertical and horizontal expansion of irrigated agriculture to feed the increasing population has contributed to excessive groundwater withdrawal and affected the availability of water in terms of both quality and quantity. To sustain agricultural growth, strategic measures should be adopted to reduce water consumption while minimizing adverse effect on yield. The effect of deficit irrigation on wheat yield was studied in three consecutive years (2002-03 to 2004-05) in field and pot. Ten irrigation treatments were imposed in a randomized complete block (RCB) design covering full deficit, no deficit at all, single deficit at different stages, and alternate deficits. Water deficit was created by withholding irrigation at different growth stages. The results indicate that deficit irrigation strategies affected all aspects of plant growth (leaf area index, chlorophyll content, root growth, nutrient uptake, plant height) adversely. Yield attributes were affected by deficit irrigation treatments although they are not statistically significant in all cases. Differences in grain and straw yield among the partial- and no-deficit treatments were small, and statistically insignificant in most cases. When compared within single-deficit treatments, the grain yield reduction was in the order to water deficit at phases: CRI> maximum tillering > booting - heading >flowering- soft dough. The crop coefficient (kc) under different ET0 methods for early, crop development, middle, and late period ranged from 0.54 to 0.96, 0.95 to 1.36, 1.2 to 1.62, and 0.68 to 1.05, respectively. On average, yield response factor (ky) for early, maximum tillering, booting-heading, and flowering-soft dough stages was 0.27, 0.21, 0.25, and 0.17, respectively. The sensitivity index (?i, of Jensen model) for early, vegetative, booting-heading, and flowering-soft dough phases was 0.35, 0.22, 0.31, and 0.14, respectively. From the evaluation of yield, irrigation amount, irrigation water productivity, relative water savings, relative yield reduction, and maximum profit under limited water resource condition, it can be concluded that when limited quantities of water is available, preference should be given to irrigate first at CRI (if one irrigation is available), then at CRI and booting-heading (if two irrigations are available), and next at CRI, maximum tillering and booting-heading (if three irrigations are available) stages of growth.
This publication comes with computer software and presents a comprehensive simulation model designed to predict the hydrologic response, including potential for surface and groundwater contamination, of alternative crop-management systems. It simulates crop development and the movement of water, nutrients and pesticides over and through the root zone for a representative unit area of an agricultural field over multiple years. The model allows simulation of a wide spectrum of management practices and scenarios with special features such as the rapid transport of surface-applied chemicals through macropores to deeper depths and the preferential transport of chemicals within the soil matrix via mobile-immobile zones. The transfer of surface-applied chemicals (pesticides in particular) to runoff water is also an important component.
Response of agricultural crops to irrigation water deficit is well-understood at the field scale. Broader scale (watershed and county levels) studies have been less frequently performed. Data collection at the field level for extensive areas is time consuming and expensive. The importance of studies at a broader scale for evaluating future scenarios of agricultural land use justifies exploring alternative approaches that produce reasonable results in a faster and more economical manner. The objective of this study was to verify the ability of coarser level data to provide general trends of changes in agricultural cropping patterns as a function of water use management in the Willamette basin. In this study, watershed and county level data were used to analyze broader scale crop water relationships, since these data are abundant and easily accessible. Further, future estimates of crop water use, based on estimates of yield and acreage changes, were attempted for a study period spanning current conditions (2000) through 2050. FAO Yield Response to Water Model was used to relate crop yield and production to applied irrigation water. Assumptions made to apply this model at the basin level related mostly to climatic factors and dynamic change of the system. Changes in maximum crop yield for all important crops grown in the Willamette basin were estimated using a logistic function parameterized with historic and current datasets. It was important to consider the dynamic system response when modeling the system to incorporate environmental, technological and socio-economic factors not reflected in the original model. The results for crop yield showed a decrease through time for sweet corn, stable yield for cherries, ryegrass, and grapes, and increasing yield for alfalfa, strawberries and raspberries. Crops showing higher sensitivity to water deficit included snap beans, winter and spring wheat, oats and filberts. Production estimates showed 3 groups of crops: predominantly successful (filberts, cherries, ryegrass, oats and spring wheat), stable (strawberries, alfalfa, orchardgrass, mint and fescue) and predominantly unsuccessful crops (winter wheat, sweet corn, snap beans and berries). County level and watershed level data proved helpful in developing a more comprehensive view of crop production and its irrigation deficit response, using models incorporating information from finer spatial scale experiments. Socio-economic, technologic and environmental variables that might influence agriculture over time should be investigated in further studies.
Water stress and heat stress are considered to be two primary factors that limit crop production in many parts of the world. Global warming appears to be increasing the water requirements of plants. Understanding the impact of water deficit on plant physiological processes and efficient water management are of great concern in maintaining food production to meet ever increasing world food demand. The book addresses various climatic soil and plant factors that contribute to the water use efficiency in plants subjected to water stress. It covers all issues related to soil, plant and climatic factors that contribute to the crop responses to water stress. The books advances the knowledge in improving and sustaining crop yields in ever increasing unpredictable climatic fluctuations This book uses crop simulation models for response of crops to limited water under various management and climatic conditions.
Results indicate that a minimum of 9% water savings can be achieved without significantly affecting the yield. Furthermore, when water is not limiting, 37% and 31% nitrogen savings can be achieved under the given experimental conditions, with conventional and fertigation method of fertilizer application, respectively, without significantly affecting the yield. A three-dimensional crop production function relating water and nitrogen to potato yield was also generated.