Effect of rice straw mulch, cowpea residue, biofertilizer and zinc foliar spray on growth and yield of summer rice in a rice-cowpea-rice cropping system in red and lateritic plains of West Bengal

Summer rice, a predominant cash crop in Southern West Bengal, India, shown waning or stagnant productivity owing to multiple abiotic and nutritional constraints. Strategic management of the inputs particularly soil water conservation, blending of different nutrient sources could aid the optimal crop growth and yield. This study focussed to evaluate the impact of rice straw mulch, cowpea residue, biofertilizer and not biofertilizer with foliar application of chelated-zinc (Zn) in sustainable summer rice production. Results of 2-year data revealed highest grain yield, yield attributes, nitrogen (N), potassium (K) and zinc uptake by summer rice were obtained from the treatment (T6), comprising combination of recommended dose of NPK fertilizers (RDF) + biofertilizer + rice straw and cowpea residue in 1:1 ratio + chelated-Zn @ 0.25% foliar spray at 15 and 30 days after transplanting (DAT). While T5 entailing RDF + biofertilizer + rice straw and cowpea residue (1:1) recorded highest soil enzymatic activity. Both T5 and T6 treatments performed reasonably well in improving soil available nutrient status (positive balance in available N and P). T7 recorded maximum irrigation water productivity, total water productivity and soil water storage through customized irrigation, swapping constant water level as maintained in T6, while remaining all other treatment components of T6 unchanged. Though B:C ratio was comparable amongst treatments, T6 and T5 proved superior for soil sustainability and water conservation. Integrating rice straw and cowpea residue along with mixed biofertilizer inoculation and early foliar application of chelated-Zn triggered potential water efficient and profitable summer rice cultivation.