Effect of paddy straw burning on soil microbial dynamics in sandy loam soil of Indo-Gangetic plains

The rice-wheat cropping system generates large quantities of crop residues and its disposal is of major concern, particularly in the Indo-Gangetic plains. A large quantity of the paddy straw is burnt on the farm to clear the field for succeeding crop, especially in the irrigated and mechanized rice-wheat system of north-west India. Besides causing air pollution, burning of paddy straw leads to the loss of soil organic matter and essential nutrients, reduces microbial activities and the land more vulnerable to soil erosion. This study was undertaken to investigate the soil microbial dynamics in response to paddy straw burning at a farmer's field in Panipat (Haryana, India). Samples were collected (0-10 cm depth ) on 0, 7, 15, 30 and 60 days from the paddy straw burnt (T1), manual harvesting or residue removed (T2) and the whole residue retained (T3) treatments. Paddy straw burning resulted in a significant reduction in the population of major groups of microorganisms-bacteria, fungi, actinomycetes, phosphate solubilizing microorganism (PSM), potassium solubilizing microorganism (KSM) and cellulose degraders immediately after burning. However, sampling after 30-60 days of burning revealed that the abundance of these groups was normalized. Similarly, the microbial enzymes and other soil health parameters showed a transient decrease after burning. Interestingly, the microbial population and enzyme activities involved in biomass recycling could not recover, even after 60 days, perhaps, due to unavailability of substrates. From a long term standpoint, this may lead to deleterious effects on soil health. (C) 2019 Elsevier B.V. All rights reserved.