Current Science

The present study documents the biological properties of the black soil region (BSR) of India in terms of culturable microbial population. Besides surface microbial population, subsurface population of individual soil horizons is described to improve the soil information system. An effort has been made to study the depth-wise distribution and factors (bioclimates, cropping systems, land use, management practices and soil properties) influencing the microbial population in the soils of the selected benchmark spots representing different agro-ecological sub-regions of BSR. The microbial population declined with depth and maximum activity was recorded within 0-30 cm soil depth. The average microbial population (log₁₀ cfu g^-1) in different bioclimates is in decreasing order of SHm > SHd > Sad > arid. Within cropping systems, legumebased system recorded higher microbial population (6.12 log₁₀ cfu g^-1) followed by cereal-based system (6.09 log₁₀ cfu g^-1). The mean microbial population in different cropping systems in decreasing order is legume > cereal > sugarcane > cotton. Significantly higher (P < 0.05) microbial population has been recorded in high management (6.20 log₁₀ cfu g^-1) and irrigated agrosystems (6.33 log₁₀ cfu g^-1) compared to low management (6.12 log₁₀ cfu g^-1) and rainfed agrosystems (6.17 log₁₀ cfu g^-1). The pooled analysis of data inclusive of bioclimates, cropping systems, land use, management practices, and edaphic factors indicates that microbial population is positively influenced by clay, fine clay, water content, electrical conductivity, organic carbon, cation exchange capacity and base saturation, whereas bulk density, pH, calcium carbonate and exchangeable magnesium percentage have a negative effect on the microbial population.

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