RICE RATOONING - IRRI books - International Rice Research Institute

Rice ratoon crop managementin the hilly regionof KarnatakaT. Gopala Reddy and M. MahadevappaTechnical Assistant, Regional Research Station, V.C. Farm, Mandya,Karnataka State, India.Professor of Seed Technology, University of Agricultural Sciences, Bangalore,Karnataka, IndiaABSTRACTRice ratoon cropping systems offer considerable potential for increasing rice productionand utilizing seasonally idle land and labor as well as residual moisture in the hillyregion of Karnataka State. Studies on ratoon crop management showed that neithercutting the main crop 35, 40, and 45 d after 50% flowering nor stubble heights cut 8,13, and 18 cm above ground at main crop harvest caused significant differencesin ratoon yields. Experiments with cutting-time intervals and cutting height aresuggested. The ratoon crop yields ranged from 76 to 350% of the main crop yields. Theratoon crop had 24% shorter growth duration and 59% higher mean yield than themain crop in an experiment at Karemane. Topdressing with 50 kg N/ha 30 d after maincrop cutting gave the highest ratoon yield. In farmers’ fields, ratoon yields ranged from0.68 to 4.58 t/ha, compared with 1.10-7.75 t/ha main crop yields. Research issuggested on stabilizing ratoon crop yields and developing suitable varieties, management.and plant protection practices.Fifty-four percent of the cultivated area of the hilly region of Karnataka is planted torice; it forms one-third of the total rice area in the state. Because rice is traditionallymonocropped and other important crops are perennial plantations (coffee,cardamom, citrus, etc.) in the hill slopes, land and labor are not fully utilized fromJanuary to May. In some small pockets a second (dry-season) rice crop is cultivatedthrough fresh plantings. But residual moisture is not enough for a newly plantedsecond rice crop in the midlands and lowlands of hill valleys, which are leftunexploited. Sometimes the growing season is too short for a newly planted cropeven if water is available, because preblossom showers start early and upland cropsare often not preferred.The newly introduced rice ratoon cropping system is aimed at utilizingresidual moisture and the short season to increase rice production at a relatively lowcultivation cost. The system also provides work to otherwise idle laborers (1, 2, 4, 5).The rainfall pattern and temperature regimes (Table 1) are conducive to high ratoonyields.