Studies on Organophophorus Pesticide Residues in Paddy Ecosystem and Evaluation of Zn and Fe Content in Paddy Grains and Soils of Gangavati Taluka in North Karnataka
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Date
2012
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UAS Dharwad
Abstract
The present studies were carried out to evaluate the organophosphorus pesticide
residues in soil, water and plant samples of paddy eco-system. The soil, water and paddy
grain samples were collected from five farmers' fields from each village in a cluster of twelve
villages and analyzed for organophosphorus residues viz., chlorpyriphos, quinalphos,
monocrotophos and dichlorvos. The soils were also analysed for different fractions of zinc
and iron and their contents in paddy grains.
The soils were neutral to strongly alkaline in reaction, non-saline, low to high in
organic carbon status with enough calcium carbonate. The analytical results indicated that
chlorpyriphos was the only chemical detected in grains. In soils, chlorpyriphos was below
detection limit and chemicals such as quinalphos, monocrotophos and dichlorvos were not
detected. In water samples also, the concentration of these chemicals were below detection
limit.
The fractionation studies indicated that the order of zinc fractions in soils were: Water
soluble + exchangeable Zn < Amorphous bound Zn < Manganese oxide bound Zn <
Organically bound Zn < Sesquioxide bound Zn < Residual Zn < Total Zn. And dominant iron
fractions were: Water soluble Fe < Exchangeable Fe < Residual Fe < Crystalline bound Fe <
Amorphous iron oxide bound Fe < Total Fe.
Zinc content in paddy grains varied from 12.17 ppm in Basapatna sample to 37.43
ppm in Karatagi sample with mean value of 21.39 ppm. Iron content ranged from 86.41 ppm
in Sangapura sample to 213.31 ppm in Karatagi sample with mean value of 115.49 ppm.
In conclusion, chlorpyriphos chemical residue was only in organophosphorus
pesticide quantified in grain samples (0.01 ppm MRL) in paddy ecosystem of Gangavati
taluka.