Impact of Fungal Biopesticide (Beauveria bassiana and B. brongniartii) on Soil Fertility in Groundnut Field

Studies were undertaken to determine the impact of Beauveria bassiana and B. brongniartii on soil fertility in groundnut field applied @ 5 x 10¹² spores ha⁻¹. It was observed that biopesticides had only temporary effect on mirobical population and enzyme activities which recovered either immediately or at the end of crop season. Insignificant changes were observed in soil except in case of exchangeable potassium. Bacterial population showed remarkable reduction on the 60th d (54%) of treatment, but finally recovered. In Azotobacter rp. continuous gradual decline in the treated field waa sbserved till harvesting, being most remarkable on 60th d (68%) and 120th d (66.7%) of treatment. Insignificant changes in the Actinomycetes sp. population were observed, whereas sungus population was sharply reduced by the 30th d, but sharp elevation by the 90th d (59.6%) was observed. Dehydrogenases activity in soil was suppressed to significant level (53%) by 60th d but was recovered by the end of experiment. Statisitcally significant decrease was observed in phosphomonoesterase activity throughout the experiment whereas arginine deaminase enzyme activity was not affected by biopesticide application.