Enhancing soil resilience and rice–greengram system productivity by locally available organic resources in cyclone-affected coastal saline soils of the Sundarbans

Seawater intrusion and recurrent cyclone-induced flooding have led to salinity buildup, posing a major constraint to agricultural productivity in the fragile coastal Sundarbans of India. The study evaluated the effectiveness of locally available organic amendments, applied individually and in combination, with recommended inorganic fertilisers (nitrogen (N), phosphorus (P) and potassium (K) (NPK)), for enhancing soil resilience, nutrient dynamics and productivity of a rice–greengram cropping system under saltwater intrusion. A two-year field experiment (comprising two cropping cycles, 2022–23 and 2023–24) was conducted in farmers’ fields using green manuring (GM) with Sesbania aculeata (Willd.) Poir., rice residues (RR) and vermicompost (VC), either individually or in different combinations. The results indicated that integrated application of organic amendments significantly improved soil organic carbon (SOC), available N, P and K and reduced electrical conductivity (ECe) compared to sole NPK and control. Among the treatments, NPK + GM + VC showed the highest soil resilience response, reducing ECe by up to 24 % and increasing SOC by 29.6 % (p ≤ 0.05) over the control. Moreover, the main effect of treatments revealed that NPK + GM + VC enhanced available N, P and K by 74.2, 58.8 and 15.4 % (p ≤ 0.05), respectively, over the control. Pooled over two years, NPK + GM + VC recorded the higher grain yield of rice (3.73 t ha-1) and greengram (0.92 t ha-1). However, NPK + GM + RR recorded the highest benefit-cost (BC) ratio under local farming conditions, primarily because VC required external procurement costs. Altogether, NPK + GM + VC emerged as the most effective nutrient management strategy for enhancing productivity and soil salinity-resilience indicators. Its economic viability could be further improved through on-farm VC production, supporting a sustainable waste-to-wealth approach for climate-resilient agriculture in the cyclone-prone coastal Sundarbans.