Vol. 10, Issue 6 (2021)

Author(s):
Ashirbachan Mahapatra, Mahesh Chandra Bhambri, Sanjoy Saha, Sushmita Munda and Nitish Tiwari

Abstract:
Though herbicides are efficient enough to control weeds, but may also have detrimental effects on the soil environment affecting the activity of soil microorganisms for a long time even in the succeeding crop. Therefore an experiment was conducted in the wet and dry seasons of 2018-19 and 2019-20 at ICAR – National Rice Research Institute, Cuttack, Odisha which was laid out in randomized complete block design comprising of ten weed management treatments in transplanted rice in wet season and the residual effects of the same treatments in green gram in dry season after harvest of the rice replicated thrice. The ten treatments were three herbicide mixtures i.e. flopyrauxifen-benzyl + cyhalofop-butyl at (25+125) g ha^-1 at 18 days after transplanting (DAT) (W₁), fenoxaprop-p-ethyl + ethoxysufuron at (50+15) g ha^-1 at 18 DAT (W₂) and cyhalofop-butyl + penoxsulam at (100+30) g ha^-1 at 18 DAT (W₃); three sequential application of herbicides i.e. bispyribac-sodium at 30 g ha^-1 at 9 DAT fb ethoxysulfuron at 15 g ha^-1 at 21 DAT (W₄), flucetosulfuron at 25 g ha^-1 at 9 DAT fb ethoxysulfuron at 15 g ha^-1 at 21 DAT (W₅) and cyhalofop-butyl at 100 g ha^-1 at 9 DAT fb ethoxysulfuron at 15 g ha^-1 at 21 DAT (W₆); two herbicide checks i.e. bensulfuron-methyl + pretilachlor at (60+600) g ha^-1 at 4 DAT (W₇) and bispyribac-sodium at 30 g ha^-1 at 2 leaf stage of weeds (W₈); one weed free check (Hand weeding at 20, 40 and 60 DAT) (W₉) and one weedy check (Untreated) (W₁₀). The dry season green gram was sown with the preceding season rice stubble mulch and minimum tillage. Soil environmental parameters viz. FDA hydrolase activity, dehydrogenase activity, β-glucosidase activity and microbial biomass carbon were analyzed at 30, 45 and 60 days after sowing of green gram. The soil environment parameters in the green gram were not significantly influenced by the weed management treatments of rice crop; and the minimum tillage and stubble mulch facilitated to gradually increase the activity of soil microbes and enzymes as the crop matured.