Conservation tillage and integrated nitrogen management stimulates soil microbial properties under varying water regimes in maize-wheat cropping system in northern India

A seven-year field study examined the interactive effect of bed planting (BP) and conventional tillage (CT) with three water regimes and eight nitrogen management options on soil respiration (SR), soil microbial biomass carbon (SMBC) and dehydrogenase activity (DHA) under a maize-wheat sequence. The BP method significantly increased the soil dehydrogenase activity (52.48%) and respiration (72.02%) over CT. Supra-optimal water regime in combination with 120 kg N ha(-1) as urea supported the least DHA in both tillage systems. The application of urea at 120 kg N ha(-1) depressed the DHA in BP (29%) and CT (30%) over their respective control. In BP and CT, input of 120 kg N ha(-1) as organics enhanced SR at supra-optimal water regime. Under BP, the substitution of green manure at 30 kg N ha(-1) increased DHA (93%), SR (36.4%) and SMBC (24.6%) over control at sub-optimal water regime. 120 kg N ha(-1) as organics recorded the maximum SMBC at the optimal water regime in BP (65% higher than control), but at sub-optimal water regime (30% higher than control) under CT. An increased soil respiration and DHA with corresponding increase in the SMBC was recorded in BP, whereas in CT, DHA declined with an increase in the SMBC.