Manav Mander
Tribune News Service
Ludhiana, November 20
Stubble burning not only spreads air pollution but also has huge impact on the soil health.
Experts say crop residue burning kills the bacterial and fungal population, which is critical for fertile soil. “As a result, crops become more prone to diseases due to loss of friendly pests and its adverse effect includes emission of greenhouse gases that contributes to global climate change,” said Dr RK Gupta, principal soil chemist at Punjab Agricultural University (PAU).
On an estimate, one tonne stubble burning leads to loss of all soil nutrients, organic carbon, 5.5 kg nitrogen, 2.3 kg phosphorus, 25 kg potassium, 1.2 kg sulphur and 400 kg carbon. In Punjab, nearly 20-22 million tonne paddy straw is produced from 3 million hectares of area under paddy cultivation. In north-western states of India, especially Punjab, Haryana and western Uttar Pradesh, about 90-95% of area under paddy is followed by wheat crop.
“Generally, farmers don’t incorporate rice straw into soil due to small period left for its decomposition along with high cost involved in its incorporation. The practice of burning rice straw causes air pollution in addition to degradation of soil health. The heat from the fire penetrates one cm into soil, which leads to rise in temperature to 33.2-42.2 degree Celsius. It leads to killing of bacterial and fungal populace, which is considered critical for soil fertility,” Gupta said.
He said burning of crop residue also damaged soil’s organic quality and other microorganisms present in the upper layer of the soil. “Due to loss of friendly pests, the wrath of enemy pests has increased and as a result, crops are more prone to diseases. The soluble capacity of the upper layer of soil has also been reduced,” he said.
Dr OP Choudhary, head, soil science, PAU, said burning of paddy straw resulted in significant reduction in the population of major groups of microorganisms — bacteria, fungi, actinomycetes, phosphate solubilising microorganism, potassium solubilising microorganism and cellulose degraders immediately after burning.
“The microbial enzymes and other soil health parameters show a transient decrease after burning and the microbial population and enzyme activities involved in biomass recycling cannot recover even after 60 days due to unavailability of substrates. This leads to deleterious effects on soil health,” Choudhary said.
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