Alteration in agronomic practices to utilize rice fallows for higher system productivity and sustainability

Rainfed rice agro-ecosystems play an important role in food production, and there is a huge scope for utilizing residual moisture in rice fallows to cultivate short-duration and low input demanding crops. However, the success of crops grown on rice fallows largely depends on the method and cultivars of rice adopted. Therefore, we examined the performance of wet season rice under different establishment methods by using different cultivars, as well as the impact of those wet-season rice treatments on post-rice crops grown during the rice-fallow of rainfed lowlands of eastern India. Rice yield was significantly higher under transplanting during all years of study, and Swarna-sub1 yielded more than the short duration cultivars (Naveen and Sahbhagidhan) due to its higher yield potential. However, transplanting the rice crop negatively affected the performance of dry season crops grown during the rice fallow; crops taken after dry-DSR (direct seeded rice) yielded more, and use of short duration cultivars in the wet season increased the yields of toria, greengram and blackgram in dry season by 37.9, 40.4 and 36.1 %, respectively. Although rice yield under dry-DSR was lower than when transplanted, the advantage of dry-DSR was the higher yield of dry season crops, resulting in almost similar system productivity to that of transplanted rice. The long duration cultivar was not profitable; although the yield was high, as a whole system the net returns and B:C ratio were as low as 5-10 % for Swarna-Sub1.The diversification of rice fallows improved the soil health in terms of fertility status, carbon fractions, microbial population and soil enzymatic activities, with more beneficial effects observed when legumes were planted. In the rice-legume systems, build up of N, P and K was 10, 24 and 7 % higher, respectively, and soil enzymatic activities were10-25 % higher, as compared to the rice-toria system. Based on the results of our study, it is recommended that short duration cultivars can be cultivated using dry-DSR in rainfed rice areas, so that a legume crop (greengram/blackgram) can be cultivated after the rice crop to achieve higher profitability, system productivity, and sustainability in the long run.