Crop Yield Response To Deficit Irrigation

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.

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.

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.

Make the best use of available water for your crops! Water Use in Crop Production explores innovative methods that determine how much water certain crops need, in certain climates, in order to ensure adequate plant growth and help eliminate water waste. Through this informative book, agronomists, growers, researchers, and graduate students will find methods and techniques for effective water management that will save money and conserve water. Water Use in Crop Production will enable you enhance crop quality and quantity and save one of the earth's most important resource. Comprehensive and thorough, this essential book combines two vital needs, food and water, and examines what must be done in order to keep up with the ever-growing human population. Explaining conservation techniques used in Argentina, Australia, Israel, Morocco, New Zealand, the Philippines, Spain, and the United States, Water Use in Crop Production will help you achieve this goal as it discusses water management measures including: avoiding excessive deep percolation reducing runoff lessening water evaporation through methods such as reducing the capillary water flow to the surface of the soil determining the rates at which water is demanded and can be supplied in a specific area to create a plan for limiting water loss studying the root structure of plants to calculate how much water they need using deficit irrigation to help plants save water for future use evaluating citrus water use through the Penman-Monteith model Containing charts, tables, and examples of the concepts it discusses, this book is the culmination of the latest studies on water storage. Water Use in Crop Production provides you with reliable strategies and methods that will help you lessen water expenditures and improve the vitality of crops anywhere in the world.

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.