Abstract

A laboratory based pot culture experiment was conducted to investigate the impact of pesticides [endosulfan, dithan-M-45 and 2,4-dichlorophenoxy acetic acid (2,4-D)] at their recommended doses on the changes in microbial biomass carbon; potentiality and proliferation of phosphorus solubilizing organisms; acid and alkaline phosphatase activities; total and available phosphorus in soil. The results of the investigation reveal that though each of the pesticides exerted deleterious effect on phosphorus solubilizing power of soil in the beginning, the overall impact was stimulatory rather than detrimental to the growth and activity of microorganisms associated with the phosphorus transformation in soil. Application of 2,4-D affected the highest level of microbial biomass carbon, growth and activity of phosphorus solubilizing microorganisms and phosphatase activity which was translated to the highest level of available phosphorus in soil. On the other hand, endosulfan brought about the least increment in the level of microbial biomass carbon; potentiality and proliferation of phosphorus solubilizing organisms; acid and alkaline phosphatase activities besides total and available phosphorus in soil. The results of the investigation reveal the safe use of each of the pesticides in the field for the eradication of pest, especially 2,4-D.

Key words: Pesticides, microbial biomass carbon, growth and activity of phosphorus solubilizing microorganisms, p-solubilizing power, phosphatases, total and available phosphate.