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

The objective of the project was to determine the nutrient requirement of HYV (high-yielding variety) rice-hybrid maize cropping system, cultivated under zero tillage. The project was initiated in 2015 in two districts of West Bengal, namely Coochbehar and Malda, having differences in agro-ecological characteristics. The Coochbehar district has Terai foothill soils, while Malda has predominantly old alluvial soils. During kharif season, rice was grown followed by maize on the same field after harvest of rice. The treatments for both of the crops included application of different doses of fertilizer such as T1: ample nitrogen (N), phosphorus (P), and potassium (K), T2: ample minus N), T3: ample minus P), T4: (ample minus K), and T5: farmer’s fertilizer practice (FFP) for the HYV rice - hybrid maize cropping system. The nutrient recommendation for the ample NPK plot was based on the Nutrient Expert^® fertilizer decision support tool for rice and maize.

Fifteen farmers' fields were chosen in each district for conducting field experiments on rice during 2016 rainy season, followed by maize in the following winter (2016–17) season. An area of 0.13 ha was allotted for each treatment. It was observed that the average rice yield for the NPK plot was over 5.5 t/ha in Coochbehar district and 5t/ha in Malda. Across both the districts, N was the most yield-limiting nutrient, followed by P and K. In the case of maize, the average productivity in the Coochbehar and Malda districts was 8.5 and 7.5 t/ha, respectively. Similar to rice, N was the most yield-limiting nutrient followed by P and K in both districts.

Overall this study has developed background information that will be useful for improving Nutrient Expert-based fertilizer recommendations, particularly for this area in West Bengal.