Impact of Weed Management Practices on Soil Microflora and Dehydrogenase Enzyme Activity Under Varying Levels of Nitrogen in Winter Season Onion (Allium cepa L.).

The study was conducted to evaluate the suitability of different weed management practices under influence of varying levels of N doses to test their effects on the various soil microflora and dehydrogenase enzyme activity in the winter onion field during 2016-2017 and 2017-2018. There were a total of twenty eight treatments replicated three times under the split-plot design (SPD). The treatments associated with weed management practices were applied to the main plots and the different N doses were given in each subplot. Microbial population and dehydrogenase enzyme activity in soil and crop weed competition index were determined. The two-hand weeding (HW) at 20 and 40 days after transplanting (DAT) of onion seedlings as well as preplant application of oxyfluorfen along with one HW at 40 DAT, exhibited a significant increase in dehydrogenase activity and microbial population in the soil when the N was applied at 100 kg ha. The study suggests that suitable weed management practices for the winter onion exerts a transient impact on soil microbial population, maintained good soil health and reduced crop-weed competition (CWC) with relatively less environmental hazards.