Can biochar conserve soil moisture and improve soil properties for sustainable intensification of acid soils in the Eastern Indian Himalayas?

The marginal Himalayan ecosystems have great potential for biochar application for conserving soil moisture, ameliorating soil acidity, improving soil fertility, and thus, contributing to sustainable intensification. Thus, the efficacy of biochar was tested along with nutrient management practices (NMP) on the performance of maize (Zea mays L.)-French bean (Phaseolus vulgaris L.) as the emerging cropping system in an acid soil under rainfed hill ecosystem. The rainy season maize was grown with three levels of biochar (0, 2.5, and 5 Mg ha-1, applied only once in the first year), and four NMP (100% recommended dose of fertilizer [RDF] [80:60:40 N:P2O5:K2O kg ha-1], 75% RDF, 75% RDF + 4 Mg ha-1 farm yard manure [FYM], and 50% RDF) under minimum tillage. After harvesting of maize, French bean was grown under no-till with four NMP (100% RDF [50:60:40 N:P2O5:K2O kg ha1], 75% RDF, 75% RDF + 4 Mg ha-1 FYM, and 50% RDF). The soil properties after 3 years viz., soil moisture, soil organic carbon (SOC), pH, and available N, P, and K status were significantly improved under 5 Mg ha-1 biochar than no biochar. Among the NMP, 75% RDF + FYM and 100% RDF had higher soil moisture, water infiltration, pH, SOC concentrations, and available N, P, and K status than others. The interaction effect of 5 Mg ha-1 biochar and 75% RDF + 4 Mg ha-1 FYM registered the highest SOC content (15.7 g kg-1). Available N was the highest in soil under 75% RDF + 4 Mg ha-1 FYM whereas, available P in soil under 100% RDF. Application of 5 Mg ha-1 biochar produced significantly the highest mean grain yield of maize and succeeding French bean. The combined application of 100% RDF and biochar 5 Mg ha-1 produced the highest maize equivalent yield. Thus, 5 Mg ha-1 biochar and application of recommended fertilizers are suggested for sustaining soil fertility and sustainable intensification of rainfed hill agriculture under acidic soil.