RICE RATOONING - IRRI books - International Rice Research Institute

Status of and potentialfor rice ratoon croppingin Tamil NaduA. Palchamy and G. SoundrapandianAgricultural College and Research Institute, Madurai - 625104, Tamil Nadu,IndiaABSTRACTIn Tamil Nadu, rice ratoon cropping is not ordinarily practiced by farmers except inisolated pockets of Cumbum Valley and Chingleput District. Twenty-five percent of thearea under rice is monocropped under canal- or tank-fed irrigation systems, wherewater is available for 190 d. A single crop of rice maturing in 130-135 d is raised eithertransplanted or direct-seeded. There is scope for raising a ratoon crop in the single-cropwetlands of Tamil Nadu, where surplus irrigation water is available for 55 d.Experiments were conducted during 1967-68 to 1984-85 to study the ratooning abilityof different short- and medium-duration varieties superimposed with the treatmentssuch as stubble height, nitrogen levels, and irrigation regimes. Cv Bhavani was foundconsistently superior to the rest as a ratoon crop, recording the maximum ratoon cropyield, accounting for 58% of the main crop yield. Harvesting the main crop atphysiological maturity stage, leaving a 20-cm stubble height, and applying 120 kgN/ha in split doses to the ratoon crop produced the maximum grain yield. The ratooncrop of Bhavani matured in 70 d and the main crop in 135 d.In Tamil Nadu, rice ratoon cropping is not ordinarily practiced by farmers, except inisolated pockets of Cumbum Valley and Chingleput District. Twenty-five percent ofthe area under rice is grown with a single crop of medium-duration varieties undercanal- and tank-fed irrigation systems. Isolated studies on ratooning of rice inTamil Nadu have shown promise for utilizing the surplus irrigation water potentialin 2.25 million hectares of double-cropped and single-cropped lowlands (Table 1).Water is available for irrigation in the double-cropped lowlands for 210-240 d,of which surplus water is available for nearly 30 d after the harvest of the secondcrop, depending upon the monsoon rains. Cropping intensity can be increased in thedouble-cropped areas — where short-duration varieties are followed by mediumdurationvarieties — either by reducing the duration of the second crop from130-133 d to 100-110 d to fit in a third ratoon crop, or by efficient water managementin selected pockets in the head zones of the command areas in different canalsystems, such as the Cumbum Valley in Tamil Nadu.The ideal situation for ratoon cropping in Tamil Nadu, however, is thesingle-cropped lowland areas (0.72 million hectares) in the canal- and tank-fedsystems, where water is available for 190 d, depending upon the monsoon rains