Impact of crop residue burning and tillage practices on soil biological parameters of rice–wheat agro-ecosystems.

In rice–wheat agro-ecosystems, crop residue burning and intensive tillage practices are conventional methods of agriculture in India which deteriorates soil and environmental quality. Present study investigated the individual impact of crop residue burning and excessive tillage as well as combined impact of both practices on soil biological parameters such as organic carbon (SOC), microbial biomass carbon (MBC), soil respiration rate, Bradford reactive soil protein (BRSP), nitrogen mineralization rate and microbial community structure at two soil depths 0–15 and 15–30 cm. Four different burning-tillage combination treatments: no-burn-no-tillage (NBNT); no-burn + tillage (NB + T); after-burn-no-tillage (ABNT) and after-burn + tillage (AB + T) were studied. The microbial community structure was investigated by phospholipids fatty acid analysis (PLFA). Results indicated that crop residue burning and tillage pose significant impact on soil biological parameters and soil microbial community especially at surface soil (0–15 cm). ABNT treatment posed a profound reduction in MBC and soil respiration rate by 54% and 34%, with respect to NBNT. Likewise, a reduction in BRSP content and SOC by 14% and 4% was noticed, while nitrogen mineralization rate enhanced by 19% in ABNT treatment. NB + T treatment significantly (P ≤ 0.05) reduced nitrogen mineralization rate, MBC and BRSP content by 58%, 48% and 25% respectively with respect to NBNT. AB + T treatment remarkably reduced MBC, SOC and BRSP content by 38%, 31% and 23% with respect to NBNT. Principal component analysis indicated that stubble burning and tillage induced a variation in soil microbial communities by ~ 61% and 23%, respectively. From our results, it can be inferred that, no burn and no tillage is the ecologically sustainable agricultural practice for maintaining the soil biological characteristics of the rice–wheat agro-ecosystems of India. [ABSTRACT FROM AUTHOR]