LAUSR

ABSTRACT Soil degradation due to salinization and sodication is the paramount threat in Indo-Gangetic plains. The studies on reclamation and management of such soils can provide a pragmatic solution for improving fertility and productivity of these soils. Lack of organic matter and poor availability of nutrients are the major factors for low productivity of sodic soils. Rice-wheat is a major cropping system in Indo-Gangetic alluvial plain region even in reclaimed sodic soils and farmers used inorganic fertilizers only to get higher yields. In this study, we used different organic sources of amendments in conjunction with different nitrogen (N) doses supplied through inorganic fertilizers to investigate the combined effect of organic and inorganic amendments on soil fertility and the productivity of rice- wheat system in sodic soils. Salt tolerant varieties of rice and wheat were grown in sodic soil (pH: 9.30, EC: 1.12 dSm−1 and exchangeable sodium percentage, ESP: 52) during 2014–15 to 2016–17 in a field experiment with 13 treatment combinations of organic and inorganic amendments (T1- (control) 100% of recommended dose of N (RDN), T2-municipal solid waste compost (MSWC) @10 t ha−1 + 50%RDN, T3- MSWC @10 t ha−1 + 75% RDN,T4- MSWC @10 t ha−1 + 100%RDN, T5-Vermicompost (VC) @10 t ha−1 + 50% RDN, T6- VC @10 t ha−1 + 75% RDN, T7-VC@10 t ha−1 + 100% RDN, T8- Farm yard manure (FYM) @ 10 t ha−1 + 50% RDN,T9- FYM@10 t ha−1 + 75%RDN, T10- FYM@10 t ha−1 + 100% RDN, T11-Pressmud (PM) @10 t ha−1 + 50% RDN, T12-PM@10 t ha−1 + 75%RDN, and T13- PM @ 10 t ha−1 + 100% RDN). Use of organic amendments supplemented with reduced dose of N through inorganic fertilizer has significantly improved soil bio-physical and chemical properties. Application of VC@10 t ha−1 + 100% RDN (T7) decreased soil bulk density, pH, EC, ESP and Na content to 2.0, 4.2, 26.5, 42.8, and 56.6% respectively and increased soil organic carbon by 34.6% over control (T1). Soil fertility in terms of available N, P, K, Ca, and Mg increased by 20.5, 33.0, 36.4, and 44%, respectively, over control (T1). Soil microbial biomass carbon, nitrogen, and phosphorus also improved significantly due to combined use of organic amendments and inorganic fertilizers over the only use of inorganic fertilizers. Decreasing in soil sodicity and increasing soil fertility showed significant increase (P < 0.05) in crop growth, growth indices, and grain yields of rice and wheat. The study revealed that combined use of VC or MSW compost @10 t ha−1 in conjunction with 75% RDN through inorganic fertilizers in sodic soils proved sustainable technology for restoration of degraded sodic soils and improving crop productivity.