Good water management practices - Rice Knowledge Bank ...

Good water management practicesWorldwide, water for agriculture is getting increasingly scarce. By 2025, 15-20 million hectares ofirrigated rice may suffer water scarcity. Therefore, care must be taken to use water wisely and reducewater losses from rice fields. A few principles exist to “get the basics right” for good water managementin paddy rice.Field channelsrice fact sheetsIn many paddy fields, water flows from one field to another through breaches in the bunds. Under suchconditions, water in an individual field can not be controlled and field-specific water management is notpossible - construction of channels to convey water to and from each field, or group of fields, greatlyimproves the irrigation and drainage of water.Land levelingA well-leveled field is aprerequisite for good watermanagement.When a field is not level, watermay stagnate in the depressionswhereas higher parts may falldry.This results in uneven cropemergence, uneven earlygrowth, uneven fertilizerdistribution, and weedproblems. See the fact sheetson land leveling for more information.TillageEffect of uneven fields.Remedy: land leveling!Wet land preparation can consume up to a third of the total water used inpaddy rice. In large-scale irrigation systems, synchronizing operations andminimizing the duration of the land preparation period can reduce wateruse.Large amounts of water can belost during soaking prior topuddling when large and deepcracks are present. A shallowtillage to fill the cracks beforesoaking can greatly reducethis water loss.Land levelingShallow tillage to fill cracks beforeland soakingCracks cause large water lossesbefore soakingAfter soaking, thorough puddling results in a compactedplow sole that reduces water losses by percolation. Theefficacy of puddling depends on soil properties. Puddlingmay not be effective in coarse soils, whereas it is veryefficient in clay soils that form cracks during the fallowperiod. Puddling may not be necessary in heavy clay soilswith limited internal drainage. In such soils, direct dryseeding on land that is tilled in a dry state is possible withminimal percolation losses.Find Out More about Water Management in Rice:Send an email to: r.lampayan@cgiar.org.Visit http://www.knowledgebank.irri.orgDownload the book “Water management in irrigated rice - Coping with water scarcity”at: http://books.irri.org/9789712202193_content.pdfor at: http://www.irri.org/publications/techbulletin/tech.asp?id=10Developed with input from: B.A.M. Bouman and R. M. LampayanProduced by the International Rice Research Institute (IRRI) • © 2009, IRRI, All rights reserved • August 2009

Good water management practices – Page 2 of 2BundGood bunds are a prerequisite to limit water losses by seepage and under-bund flows. Bundsshould be well compacted and any cracks or rat holes should be plastered with mud at thebeginning of the crop season. Also, check for, and repair new rat holes, cracks, and porositycaused by earth worms throughout the growing season. Plastic sheets can be used to repairespecially permeable parts of bunds.rice fact sheetsClose rat holesPonded water depthGood bunds avoid seepage lossesKeeping the depth of ponded water around 5 cm minimizes water losses by seepage andpercolation. See the fact sheet on Alternate Wetting and Drying for more information on fieldwater management.Find Out More about Water Management in Rice:Send an email to: r.lampayan@cgiar.org.Visit http://www.knowledgebank.irri.orgDownload the book “Water management in irrigated rice - Coping with water scarcity”at: http://books.irri.org/9789712202193_content.pdfor at: http://www.irri.org/publications/techbulletin/tech.asp?id=10Developed with input from: B.A.M. Bouman and R. M. LampayanProduced by the International Rice Research Institute (IRRI) • © 2009, IRRI, All rights reserved • August 20092