Comparison of biological soil quality indicators under different nutrient management techniques in semi-arid parts of India

Exploring the effect of organic and chemical input management practices on soil biological variables in tropical areas of Tamil Nadu may help to develop sustainable nutrient management practices. A systematic study on the effects of different nutrient management practices on soil biological indicators is lacking. Hence, the field experiment was conducted involving four nutrient management practices, viz., integrated nutrient management (INM), conventional nutrient management (CNM), organic nutrient management (ONM), and farmers practicing nutrient management (FNM) at 2 different soil depths (0-15 and 15-30 cm) in western agro-climatic zone of Tamil Nadu. The data across the nutrient management practices revealed that soil pH and EC were greatest in CNM, whereas higher available N, P, K, SOC, SOM, DOC, MBC, count on microbes and earthworms, microbial indices MBC/SOC ratio, fungal/bacteria ratio, and enzyme activity were higher in ONM. The relationship between biological indicators was assessed by correlation and using a principal component analysis, and two components accounted for 96.9% variance. The study found that SOM, SOC, MBC, and microbial counts are the major drivers for variability among the nutrient practices. The results signify that biological indicators are influenced by different nutrient management practices in the semi-arid tropical vertisols through the resilience of SOC.