Soil biochemical quality indices can capture transitional changes of tillage and residue regime in lateritic soils

Aiming to evaluate the sustainability and ecological viability of the rice-wheat system, field experiment was conducted at experimental farms of IIT Kharagpur, West Bengal, India in 2022-24 to assess how Conservation Agriculture (CA) based practices influence soil biochemical changes throughout the growth stages of rice and wheat. Under this experiment, the impact of varying tillage treatments (conventional tillage vs. zero tillage) and residue management practices (incorporated vs. retained) on soil biochemical properties in a rice-wheat cropping system was evaluated during the first year transitional period of adaptation of CA. This experiment was laid out in a randomized block design (RBD) with eight treatments among which rice residue retention, rice residue incorporation treatments along with no residue application were adopted over different crop establishment practices viz. conventional tillage (CT) and zero tillage (ZT). Key parameters such as soil organic carbon, soil microbial biomass carbon, enzyme activities (including dehydrogenase, phosphatase, and urease) were monitored during this transitional period of CA adaptation and compared with CT practices. The results showed that ZT practices, coupled with residue retention (RR), significantly enhanced Walkley black carbon (WBC) content at top 15 cm of soil by 0.33% at this transitional period compared to conventional tillage where WBC content was reduced by 1.55% from initial values. Enzyme activities, particularly dehydrogenase and phosphatase, were higher under zero till and residue retention treatments, indicating improved microbial activity and nutrient cycling. Soil respiration rates were also higher in zero till plots, suggesting an increased microbial turnover and organic matter decomposition. In contrast, conventional tillage with incorporated residue exhibited higher soil compaction, reducing microbial activity and overall biochemical quality indices. The findings highlight that conservation tillage, specifically zero till systems with residue retention, offers substantial benefits for improving soil biochemical health and sustainability in lateritic soils. This system can potentially enhance carbon sequestration, promote soil microbial biodiversity, and improve nutrient cycling, making it a viable strategy for sustainable agriculture in tropical and subtropical regions.