How much water does rice need? - adron.sr

Rice on theby Yothin Konbooncutting edgeSometimes the best inventions are accidental. In northeastern Thailand, farmersare adopting a weed-control method first taught to them by their animals.yothin konboonIf performed correctly, thepractice of planting rice bybroadcasting rice seeds directlyinto unflooded soil offersseveral advantages over the usualpractice of transplanting seedlingsinto flooded fields. Farmers can savetime and labor, less water is requiredto establish the crop, and dry directseededrice suffers less from earlyseasondrought. These are importantadvantages, especially in rainfed rice,and dry direct seeding is gainingpopularity in a number of areasacross Asia. According to the ThaiOffice of Agricultural Economics,around 38% of rainfed rice (reliant onrain with no irrigation infrastructure)in northeasternThailand in 2005was planted todry directseededrice, andthis figure isgrowing.The main problem withdirect-seeded rice is weed control.Transplanting seedlings gives ricea head start over weeds, and acontinuous layer of water suppressesweed growth. In northeasternThailand, the methods used tocontrol weeds differ from placeto place. Some farmers followofficial agriculture departmentrecommendations while othersdevelop their own methods.One of the most promisingfarmer-initiated controls is ricecutting, a method first studied in1998 in deepwater rice by Thairesearcher Tawee Kuptkarnjanakul.Because deepwater rice is plantedvery early in the season, the periodbefore flowering is long, resultingin excess growth of leaves andshoots. Farmers would cut theleaves just above the water surfaceprimarily to use as animal feed.In northeastern Thailand, ricecutting began around 10 years ago,but not as a result of transfer fromdeepwater rice systems. Early-seasondrought is a regular occurrence inthe region and direct-seeded cropsfrequently suffer. When this occurs,some farmers give up on theircrop, leaving it for their animalsto graze. Over the years, farmersCUTTING RICE with aswing grass mower canhelp control weeds.have discovered that, when therains finally resume, the grazedcrop recovers well and ends upyielding a reasonable harvest.After a few years of trial anderror, farmers in different areasdeveloped their own rice-cuttingmethods, which all include cuttingdown weeds as well as rice earlyin the season. In some places,cutting is done primarily to reduceweed competition; in others, itis to improve soil fertility. Thepractice is spreading throughfarmer-to-farmer communication,media campaigns, and extensionworkers (the people responsiblefor technology dissemination).However, farmers’ and researchers’understanding of the benefits of ricecutting, and the conditions underwhich it succeeds or fails, is stillvery limited. Therefore, Thailand’sUbon Ratchathani Rice ResearchCenter (URRC)—with assistancefrom the Consortium for UnfavorableRice Environments (CURE), agroup of national and internationalinstitutions led by the InternationalRice Research Institute—hasrecently conducted farm surveysto study and test this technology.Farmers who practice rice cuttingsay that it boosts their rice yieldssubstantially, with some claimingthat it also improves soil fertility.They tend to use the method withtall, photosensitive rice varieties—that is, varieties that flower inOctober independent of the sowingdate—including Thailand’s famousjasmine rice. Once the rice crop hasbeen established, it is managed asusual until late July–early Augustwhen the rice cutting is conducted.This leaves around 50 days before18 Rice Today January-March 2009