Impact of Pesticides on Soil Health-a Comparative Study conducted on Conventional and Organic Tea Gardens of Dooars Region, West Bengal

Author: Rahul Kumar Mishra, Soumya Shukla and Md. Abdullah Khan

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Abstract

Tea, world’s second most popular beverage is drunk for its numerous health benefits and refreshment. Tea grows well in warm humid climate with an annual rainfall of more than 115 cm. The environmental conditions such as high relative humidity and temperature above 35˚C is favourable for disease development and to control them synthetic pesticides are used extensively. Dooars – Terai regions of North Bengal which contributes 21% of India’s total tea production has background of highest pesticide use in the country. Pesticide residues have many adverse effects on soil health and even on human health. Present study aims to study the impacts of these pesticides on the beneficial soil microflora and physico-chemical properties of soil of both conventional and organic tea gardens. This study has been conducted in the Western Dooars region of North Bengal. Samples of two different age groups (10 years and 40 years old tea gardens) were collected from 7 tea estates (five conventional and two organic) from Jalpaiguri and Kalimpong districts and were analyzed. The samples were collected during the December 2022 to January 2023. For physico-chemical properties pH, Total Organic Carbon, Available nitrogen, phosphorus, and potassium were studied. For microflora total bacteria, total fungus, Actinomycetes, Azospirillum sp., Pseudomonas, Micrococcus, Azotobacter sp., etc. were studied. Serial dilution and plate count method was used to study the microflora whereas physico-chemical properties were studied by their respective methods. The results revealed almost all conventional soil samples have less microbial counts than the soil samples taken from organic tea gardens. Some conventional soil has high content of available Nitrogen, available Phosphorus but they have less N2 fixing bacteria, phosphate solubilizing microorganisms which is a matter of concern. Pesticides do not have any negative impact on the Actinomycetes and Azotobacter and their CFU count in both the sample soil types were similar. Pesticide alters the pH of the soil which leads to changes in the solubility of macronutrients and micronutrients. For proper productivity and sustainability of soil ecosystem tea producers should focus more on biopesticides and other alternatives.

Keywords

Pesticides, Microflora, Sustainability, Ecosystem, Health

Conclusion

The pH of all the soil samples is found to be acidic but some tea estates have pH of around 6 and more which is a matter of concern as high pH reduces the solubility of macronutrients as well as micronutrients. Pesticides have no side effect on Azospirillum sp. (free living N2 fixing bacteria), rather they degrade the pesticide to some extent and use it as a source of energy. Although some conventional tea gardens have medium to high amount of Phosphorus but the CFU of Phosphate solubilizing bacteria and Phosphate solubilizing fungus is low which may lead to series adverse impacts in the productivity as well as soil health. Organic Tea Garden’s soil has more total bacteria than Conventional tea garden’s soil. The number of Total Bacteria is found to be more in 40 years old plantations than 10 years old plantation. In comparison with some conventional tea gardens, organic tea gardens with relatively high fungus and nitrogen-fixing bacterial populations have slightly lower available nitrogen levels. There is cause for worry since some conventional tea gardens with a lot of readily accessible nitrogen do not have many free-living N2 fixing bacteria. The use of biological pest control agents (natural enemies of insect pests), biopesticides should be done in order to minimize these side effects and ensure proper productivity, quality and sustainability of tea ecosystem.

References

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How to cite this article

Rahul Kumar Mishra, Soumya Shukla and Md. Abdullah Khan (2023). Impact of Pesticides on Soil Health-a Comparative Study conducted on Conventional and Organic Tea Gardens of Dooars Region, West Bengal. Biological Forum – An International Journal, 15(5a): 473-480.