Abstract
The use of fungicides is the continuous exercise particularly in orchard crops where fungal diseases, such as white root rot, have the potential to destroy horticultural crops rendering them unsaleable. In view of above problem, the present study examines the effect of different concentrations of mancozeb (0–2000 ppm) at different incubation periods for their harmful side effects on various microbiological processes, soil microflora, and soil enzymes in alluvial soil (pH 6.8) collected from apple orchards of Shimla in Himachal Pradesh (India). Low concentrations of mancozeb were found to be deleterious towards fungal and actinomycetes population while higher concentrations (1000 and 2000 ppm) were found to be detrimental to soil bacteria. Mancozeb impaired the process of ammonification and nitrification. Similar results were observed for nitrifying and ammonifying bacteria. Phosphorus solubilization was increased by higher concentration of mancozeb, that is, 250 ppm and above. In unamended soil, microbial biomass carbon and carbon mineralization were adversely affected by mancozeb. Soil enzymes, that is, amylase, invertase, and phosphatase showed adverse and disruptive effect when mancozeb used was above 10 ppm in unamended soil. These results conclude that, to lessen the harmful effects in soil biological processes caused by this fungicide, addition of higher amount of nitrogen based fertilizers is required.
Highlights
Agriculture relies on chemicals to control weeds, pest, and diseases
There is, a close relationship between pesticides and microorganisms because (i) these chemicals may have a deleterious effect on nontarget organisms and (ii) most of these pesticides being organic in nature could be metabolized by microorganisms resulting in modification of their activity
Pesticides gain entry into soil by a variety of means and their effect on soil microbial population may lead to elimination, decrease, or modification of microbial transformations and soil enzymes considered essential for soil fertility [2]
Summary
Pesticides include chemicals differing in their mode of action and are used by man as intentional addition to his environmental to control or eradicate a specific pest of economically important crops. They are intended for harmful organisms but they get into the nontarget system and bring about substantial impact on the ecosystem ranging from general poisoning to carcinogenic effects [1]. There is, a close relationship between pesticides and microorganisms because (i) these chemicals may have a deleterious effect on nontarget organisms and (ii) most of these pesticides being organic in nature could be metabolized by microorganisms resulting in modification of their activity. Pesticides gain entry into soil by a variety of means and their effect on soil microbial population may lead to elimination, decrease, or modification of microbial transformations and soil enzymes considered essential for soil fertility [2]
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