Soil organic carbon, dehydrogenase activity and fluorescein diacetate as influenced by contrasting tillage and cropping systems in Vertisols of Central India

Aim : The present study aimed to compare the effects of different tillage systems and cropping systems on soil biological activity in terms of soil organic carbon, labile carbon, dehydrogenase activity, fluorescein diacetate activity and crop productivity. Methodology : The yield data of different cropping systems were converted in soybean grain equivalent yield using minimum support price based on 2015 and expressed in q ha(-1). Soil samples were collected randomly from 2-3 locations from the plots at the end of 3 crop cycles at 0-5 and 5-15 cm depths during April 2014 with the help of core sampler and processed. The soil samples were analysed using standard analytical procedures. Results : Within tillage system, soil organic carbon was recorded higher in reduced tillage (0.67%), compared to no tillage (0.66%) and conventional tillage (0.62%) at 0-5 cm depth. The labile carbon in surface soil (0-5 cm) followed same trend of soil organic carbon, whereas at 5-15 cm depth, it followed the trend : no-tillage > reduced tillage > conventional tillage. Furthermore, soil enzymatic activity was significantly affected by the imposed tillage systems. The results of dehydrogenase activity reported higher in no-tillage system compared to reduced and conventional tillage; whereas fluorescein diacetate hydrolysis was reported higher in reduced tillage followed by no-tillage and conventional tillage at surface soil (0-5 cm). Pearson correlation (r) showed significant correlations between soil organic carbon and soil biological parameters. It was inferred that cropping system had a significant effect on soybean grain equivalent yield at end of 3 crop cycles. The results of this study also confirmed effectiveness of studied parameters as soil indicators owing to sensitivity towards management practices. Interpretation : Soil microbial activities greatly influenced with depth as in the upper layer than 5-15 cm depth. Significantly positive correlation between soil organic carbon and microbial activities indicated enhanced microbial biodiversity, maintaining a better environment for stabilizing soil quality due to tillage and cropping systems applied.