Tillage and crop establishment options for enhancing the productivity, profitability, and resource use efficiency of rice-rabi systems of the salt-affected coastal lowlands of eastern India

摘要

Farmers in the rainfed salt-affected coastal areas of eastern India face challenges of flooding, salinity, scarcity of irrigation water, and insufficient rainfall that affect crop production and environmental sustainability. This study evaluated three rice establishment methods [dry-seeded rice (DSR), non-puddled transplanted rice (Non-PTR), and puddled transplanted rice (PTR)] during the wet season/kharif and three tillage practices [zero-tillage (ZT), conventional tillage (CT), and raised-bed sowing (RBS)] for dry-season/rabi crops (maize and rapeseed) in a replicated experiment. The experimental site was in the rainfed and salt-affected coastal lowland area of West Bengal, India, and rice was grown in three successive wet seasons (2013-16), with each rice crop followed by maize or rapeseed in the dry season. Transplanted rice was adversely affected by submergence each year due to heavy rain after transplanting, whereas DSR was less affected as the plants were taller at the time the heavy rains began. Rice grain yields were similar (4.5-5.1 t ha(-1)), however, among the three rice establishment methods, and, further, rice yields were not affected by rabi-season tillage practices. The net returns and the benefit-cost ratio (BCR) were greater in DSR because of the reduced costs of land preparation. Rapeseed grown after non-puddled rice (DSR and Non-PTR) gave 25-44% higher yield than rapeseed grown after PTR, and the yields of maize were 8-13% higher when grown after either DSR or Non-PTR than after PTR. DSR and Non-PTR also had positive effects on soil quality: bulk density was lower after the third-year rice crop and soil salinity decreased during each dry season (Dec-April) just after the rice crop compared with PTR. Maize yield was highest in RBS (5.8 t ha(-1)), followed by CT (4.1 t ha(-1)) and ZT (3.6 t ha(-1)), whereas rapeseed produced the highest yield under ZT (0.86 t ha(-1)) vis-a-vis RBS and CT (0.6 t ha(-1)). Net returns for maize were highest with crops on RBS and in rapeseed with ZT. Maize provided a higher economic return than rapeseed (USD 301-405 ha(-1) in maize; USD 5-113 ha(-1) in rapeseed) but it (maize) required 25 cm more irrigation water and 3 GJ ha(-1) more energy input for cultivation. This study indicates that rice-maize could be more profitable than rice-rapeseed for the salt-affected coastal areas in India, and that, to improve productivity and profitability in this rotation, rice should be established as DSR or Non-PTR followed by maize on FIBS in the coastal regions.