Soil organic carbon and biochemical properties affected by tillage, mulching and mineral fertilization under rice-based cropping systems in the Indo-Gangetic Plains

A field trial was conducted for four years at Modipuram, Uttar Pradesh, to delineate the impacts of tillage, cropping systems and residue mulching at different rates of mineral fertilization on crop productivity, soil health and enzyme activities. Two tillage systems (no tillage and conventional tillage), four cropping systems [C1: rice (Oryza sativa)-wheat (Triticum aestivum), C2: rice-winter maize (Zea mays), C3­: rice-barley (Hordeum vulgare) and C4: rice –mustard (Brassica spp)] and four rice residue mulching along with mineral fertilization (M1: No mulch + recommended dose of mineral fertilizers (RDF), M2: Mulch (at 6 Mg ha-1) + RDF, M3: No mulch +125% RDF and M4: mulch (at 6 Mg ha-1) + 125% RDF) were used. Results indicated that ZT had ~16% higher oxidizable SOC concentration than CT plots in the surface layer. Although surface oxidizable SOC was unaffected by cropping systems, M4 plots had ~49 and 45% higher oxidizable SOC concentration than M1 and M3 plots, respectively. In surface layer, ZT was better than CT, C1 and C2 were better than C3 and C4 plots, and M4 was better than M1, M2 and M3 plots in terms of dehydrogenase activity. Rice-wheat cropping system had maximum system productivity than other cropping systems and both ZT and CT plots had similar system productivity, but ZT plots had better soil quality indicators. Hence, it is recommended that 6 Mg ha-1 rice residues with 25% higher mineral fertilization under ZT may be adopted for sustained productivity in the rice-wheat cropping system.