Study and prediction of persistent organochlorine and organophosphorous pesticide residue in soils of cardamom plantations in Idukki district (India)

Abstract

The indiscriminate use of toxic pesticides had created an environment that without this poison the plant life is unfruitful leading to the farmer's life miserable. For several years, this phenomenon was continuing and the ecosystem is protecting the environment and the life of human being from high risk of toxicity. But, how long it will continue or weather a paradigm change in the agricultural field is required? With this objective a field study was conducted in the cardamom plantations of Idukki district in South India to estimate and predict the persistence of pesticide residue in the soil environment. It is observed that residues of endosulfan, DDT and organophosphorous pesticides were present in soil samples at 31.6 %, 29 % and 21 % respectively. The present study gives a prediction of the concentration of persistent pesticide residues in the soil if the present dose and frequency of application is continued. The study also highlighted the adsorption capacity of soil in the study area and low water solubility of pesticides used in cardamom plantations which is referred as partition coefficient. The soil properties such as pH, organic content and microbial concentration which determine the fate of degradation of pesticides and formation of its metabolites are also been discussed in this context. Based on the observations and analysis, it is concluded that the formation of degradation products and bound residues decrease at higher concentration of pesticide applications but the concentration of persistent pesticides increases and the biodegradation reduced in such cases due to bound residues and reduced biological activity. The predicted values on multiple applications where the concentrations in soil may build up and reach a plateau, are 2.559,0.2559, 1.7324 and 0.659 mgKg -1 in the case of endosulfan, DDT, organophosphorous and