Soil microbial communities and enzymes as affected by herbicides of rice-wheat and soybean- wheat cropping system

Abstract

A field study was conducted to study the long term impact of continuous use of herbicide on microbial activity in rice-wheat and soybean- wheat cropping system. In the present investigation, non herbicide treatments such as hand weeding and weedy check showed higher activity as compared with herbicide receiving treatments. In rice, among the two herbicides, application of butachlor had less adverse effect when compared to the application of anilophos on soil microorganisms. Actinomycetes population maintained stable after the application of herbicides. Among the different herbicide application practices, maximum dehydrogenase activity (27.7µg TPF/g soil/24hrs) and urease activity (44.5µg NH4/g soil/24hrs) was observed in anilophos and butachlor treatment respectively. The treatment preceding wheat crop did not influence the microbial and enzyme activities. In soybean, highest population of total bacteria (3.34×106cfu/g) and actinomycetes (2.47×103 cfu/g) were observed in one hand weeding treatment. The treatment preceding wheat crop did not influence the basic microbial activities. However, it positively influenced dehydrogenase activity in all the three rabi season herbicides. This study clearly indicated that herbicide application had not significant effect on the soil microbial population and soil enzymes.