Influence of continuous and rotational use of herbicides in rice under rice-wheat system on non-target soil microorganisms.

摘要

A long term experiment on commonly used herbicides in rice under rice-wheat rotation system was conducted on a permanent plot in Karnal, Haryana, India, since 1999. Rice rhizosphere soil samples of the experiment during the kharif seasons of 2005-06, 2006-07 and 2007-08 were collected at different time intervals after the application of herbicide (butachlor at 1500 g/ha used as fixed herbicide and butachlor at 1500 g/ha in the 1st year in 2002, pretilachlor at 100 g/ha in the 2nd year or anilofos at 400 g/ha in the 3rd year used as rotational herbicides) and analysed for total bacterial, fungal, actinomycetes and free living diazotroph populations. Total bacterial population was more in green manuring with Sesbania treatments than without green manuring treatments. Bacterial population was significantly less in fixed and rotational herbicide-treated plots than the weedy control at early stages after the application of herbicides. However, actinomycetes population was slightly higher in herbicide-treated plots compared to the weedy control at early stages after treatment. Fungal and free living diazotroph populations were not affected by the application of herbicides.