Long-term Effect of Tillage, Residue and Biofertilizer on Soil Microbial Biomass Carbon and Dehydrogenase Activity under Rice-wheat Cropping System in Terai Agro-ecological Region of West Bengal

As a major supply of staple foods, the rice-wheat cropping system is crucial to global food security. However, continuous cultivation of these crops has led to several soil-related environmental problems, including the gradual decline in soil health and quality. In this context, maintaining soil health necessitates the adoption of conservation agriculture. This study assessed the effect of tillage, residue and biofertilizer management practices on soil dehydrogenase activity (SDHA) and soil microbial biomass carbon (SMBC) of post wheat soils at various soil depth (0-5 cm, 5-10 cm, 10-20 cm and 20-40 cm). The research was conducted as part of a long-term field experiment initiated in 2006 in rice-wheat cropping system under a factorial randomized block design with three replications in the Terai agro-ecological regions of West Bengal. The results revealed that the SDHA and SMBC were increased by the influence of long-term zero tillage, bio fertilizer & residue addition at the most of the soils depths under study except at 20-40 cm. The highest short-term change of SDHA (213.19%) in compared to the initial soil status was observed in conventionally tilled soil with biofertilizer addition treatment combination. Since SDHA and SMBC are critical indicators of soil health and quality, this study also explored their relationship. Positive good regression coefficient of 0.74, 0.65 and 0.67 at 0-5 cm, 5-10 cm and 10-20 cm soil depth were observed respectively. These findings highlight the strong association between the two parameters. With growing future demand of foods, conservation agriculture must be practiced to ensure the long-term sustainability of soil productivity. The study provides evidence that implementing zero tillage along with residue and biofertilizer addition significantly improves these key soil health parameters.