Optimising nutrient use efficiency under zero tillage operations in Rice - Maize cropping system in Coochbehar and Malda district of West Bengal

The project objectives were to determine the nutrient requirement of a high-yielding variety (HYV) rice-hybrid maize cropping system under zero tillage cultivation, and use the Nutrient Expert fertilizer decision support tool to develop farm-specific recommendations for a rice-maize cropping system. The project was initiated in 2015 in two districts of West Bengal, namely Coochbehar and Malda, with differing agro-ecological characteristics. Coochbehar district is in the foothills of the Himalayas, while Malda is in the old Gangetic alluvial region of the state. The study under HYV rice - hybrid maize cropping system included five treatments, namely T1, site-specific application of nitrogen (N), phosphorus (P), and potassium (K) and secondary and micronutrients based on Nutrient Expert® tool for rice and maize; T2, omission of N from T1; T3, omission of P from T1; T4, omission of K from T1; and farmer’s fertilizer practice (FFP).

Fifteen farmers from each district were chosen for conducting the field experiments in rice and maize during the 2015 and 2016 cropping seasons. The average rice yield was 5.2 t/ha in the farmers' fields in Coochbehar. Across the sites, N was the most limiting nutrient followed by P and K. Phosphorus was the most limiting nutrient in two sites, while K was most limiting in four out of fifteen sites. In Malda district, N was most limiting nutrient in more than 50% of the total farm units followed by P (47%) and K (40%). In the first two rice seasons of the project, the nutrient omission results have helped to identify the most limiting nutrients responsible for reduction in productivity. The omission plot data also helped determine the indigenous nutrient supplying capacity of fields in the two districts. Overall, this study is helping increase awareness among farmers about the adverse effect of macronutrient omission in rice-maize cropping system, and disseminating the Nutrient Expert tool for empowering field research and extension scientists to deploy farm-specific fertilizer recommendation in northern West Bengal.