Deficit Irrigation

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 book focuses on proving that deficit irrigation could play an important role in increasing food production in times of water scarcity. Although the application of deficit irrigation can involve loss in crop productivity, it still secures water to be use in cultivating more lands and producing more food. The following questions are discussed and the authors offer solutions to these problems: Will the production, on a national level, resulting from these new added areas compensate yield losses attained by application of deficit irrigation? Is it possible to use deficit irrigation practice to reduce the applied irrigation water to certain crops that have a surplus in their production, and direct this saved water to cultivate new areas with crops have low self-sufficiency ratios? Under climate change in 2030, would deficit irrigation practice have the same role it plays under the current conditions? This book will appeal to students and researchers involved with water scarcity and food security.

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.

This book focuses on proving that deficit irrigation could play an important role in increasing food production in times of water scarcity. Although the application of deficit irrigation can involve loss in crop productivity, it still secures water to be use in cultivating more lands and producing more food. The following questions are discussed and the authors offer solutions to these problems: Will the production, on a national level, resulting from these new added areas compensate yield losses attained by application of deficit irrigation? Is it possible to use deficit irrigation practice to reduce the applied irrigation water to certain crops that have a surplus in their production, and direct this saved water to cultivate new areas with crops have low self-sufficiency ratios? Under climate change in 2030, would deficit irrigation practice have the same role it plays under the current conditions? This book will appeal to students and researchers involved with water scarcity and food security.

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 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.

This bestselling manual is the definitive guide to olive production in California. This 180-page manual is fully illustrated with 40 tables, 19 line drawings, and 36 charts, and 100 color and black and white photos. The most notable additions to this edition include a new chapter on deficit irrigation, a greatly expanded chapter on olive oil production, and coverage of four new pests, including the olive fly. Includes production techniques for commercial growers worldwide - from orchard planning and maintenance to harvesting and postharvest processing. Contains information on pollination, pruning for shaker and vertical rotating comb harvest, mechanical pruning, deficit irrigation, mechanical harvesting methods including trunk-shaking and canopy contact harvesters, postharvest handling and processing methods, and olive oil production. Also includes information on new pests including olive fly, oleander scale, olive mite, and black vine weevil.