Water management in irrigated rice - Rice Knowledge Bank ...

PrefaceWorldwide, about 79 million ha of irrigated lowlandsprovide 75% of the total rice production.Lowland rice is traditionally grown in bundedfields that are continuously flooded from cropestablishment to close to harvest. It is estimatedthat irrigated lowland rice receives some 34–43%of the total world’s irrigation water, or 24–30%of the total world’s freshwater withdrawals. Withincreasing water scarcity, the sustainability, foodproduction, and ecosystem services of rice fieldsare threatened. Therefore, there is a need to developand disseminate water management practices thatcan help farmers to cope with water scarcity in irrigatedenvironments.This manual provides an overview of technicalresponse options to water scarcity. It focuses onwhat individual farmers can do at the field level,with a brief discussion on response options at theirrigation system level. The manual is meant as asupport document for training on water managementin rice production. It combines scientificbackground information (with many literature referencesfor further reading) with practical suggestionsfor implementation. The target audience is peopleinvolved in agricultural extension or training withan advanced education in agriculture or watermanagement, who wish to introduce sound watermanagement practices to rice farmers (such as staffof agricultural colleges and universities, scientists,irrigation operators, and extension officers).Introductory chapters analyze the water use andwater balance of rice fields, and water movementin the plant-soil system, and discuss the conceptsof water scarcity and water savings. Consequencesof water scarcity for sustainability, environmentalimpacts, and ecosystem services of irrigated ricefields are discussed at the end. An appendix introducestwo simple instruments to characterize thewater status of rice fields that can help farmers inapplying water-saving technologies.This manual was developed through the WaterWork Group of the Irrigated Rice Research Consortium(which is co-funded by the Swiss Agencyfor Development and Cooperation). The sectionson aerobic rice were co-developed by the CGIARChallenge Program on Water and Food throughthe project “Developing a System of Temperateand Tropical Aerobic Rice in Asia (STAR).” Manypartners from national agricultural research andextension systems in Asia have contributed to thework described in this manual. The manual wasreviewed by Dr. Ian Willet (Australian Centre forInternational Agricultural Research) and Dr. MohsinHafeez (CSIRO Land and Water).The authorsLos Baños, 2007iv