Rice (Oryza sativa)-based system intensification in north-eastern India: Effect on yield, economics and soil properties

Attempt was made to adjust three rice crops in a cropping sequence in irrigated lowland, and also to compare productivity and efficiency of rice (Oryza sativa L.)–rice–rice cropping system with rice–rice and rice–fallow. Results of the 8 years study (2001–09) revealed that rice variety ‘Chandrama’ as winter crop, followed by the same variety as summer crop and ‘Vandana’ as autumn crop could be grown in sequence. The grain yield from the 3 rice cropping sequence was 15.3 t/ha. The productivity of the summer crop (6.8 t/ha) was the highest, followed by the winter crop (5.6 t/ha). The lowest productivity was obtained from autumn crop (2.9 t/ha). Rice–rice cropping system produced the lower grain yield of 12.4 t/ha. However, considering production efficiency (48.8 kg grain/ha/day), sustainable yield index (0.98), net return (23,187/ha) and benefit: cost ratio (1.43), it was better than rice– rice–rice cropping system. Results on soil chemical properties after eight cropping cycles under rice–rice–rice cropping system revealed that soil pH and available N content were similar to the initial value. However, a buildup of organic carbon (12%), and available phosphorus (39.5%) and potassium (6.4%) in soil was noted.