Effect of pendimethalin and quizalofop on N2-fixing bacteria in relation to availability of nitrogen in a Typic Haplustept soil of West Bengal, India

Abstract

An experiment was conducted under laboratory conditions to investigate the effect of two systemic herbicides viz., pendimethalin and quizalofop, at their recommended field rates (1.0 kg and 50 g active ingredient ha(- 1), respectively) on the growth and activities of non-symbiotic N(2)-fixing bacteria in relation to mineralization and availability of nitrogen in a Typic Haplustept soil. Both the herbicides, either singly or in a combination, stimulated the growth and activities of N(2)-fixing bacteria resulting in higher mineralization and availability of nitrogen in soil. The single application of quizalofop increased the proliferation of aerobic non-symbiotic N(2)-fixing bacteria to the highest extent while that of pendimethalin exerted maximum stimulation to their N(2)-fixing capacity in soil. Both the herbicides, either alone or in a combination, did not have any significant difference in the stimulation of total nitrogen content and availability of exchangeable NH(4)(+) while the solubility of NO(3)(-) was highly manifested when the herbicides were applied separately in soil.

Microbial Consortia for Sustaining Productivity of Non-legume Crops: Prospects and Challenges

“…Shukla and Das [76] reported that Nitrosomonas population at 1-3 ppm while Nitrobacter population at 1-2 ppm of pendimethalin were comparable with that in control, indicating no or very little effect of pendimethalin even at these very high doses of application. Das et al [17] observed that pendimethalin and quizalofop applied at recommended rates solely or in combination stimulated aerobic nonsymbiotic N-fixing bacteria. The MC and biofilms may respond to herbicides/pesticides in similar way as the individual microbe does, and this opens up the possibility of their use in modern agriculture.…”

Non-symbiotic N2-fixation and phosphate-solubility in Gangetic alluvial soil as influenced by pre-emergence herbicide residues

“…As compared to untreated control, the higher stimulation of microbial population was manifested at lower concentrations of the herbicides, being the highest under thiobencarb (54.0%) followed by pretilachlor (25.2%), while the threefold increase in concentration of the herbicides over the field application rates exerted less stimulatory effect towards the growth and proliferation of aerobic non-symbiotic N 2 -fixing bacteria in soil. The significant rise in microbial population during 15-30 days followed by a gradual decrease up to 60 days of sampling, pointed out that aerobic non-symbiotic N 2 -fixing bacteria preferably utilized the incorporated herbicide residues and their degraded fractions as their source of carbon, energy and other nutrient elements for their cellular metabolism (Debnath et al, 2002;Das et al, 2012b). Consequently, the amount of herbicidal residues was gradually depleted in the later incubation periods, resulting in less number of bacterial colonies in the subsequent sampling days.…”

Impact of Pre and Post Emergence Herbicide Application on Soil Microbial Population Assessment in Direct Wet Seeded Rice

“…On the other hand, some research evidences exhibit that herbicides show stimulating effect on growth and metabolism of non-symbiotic nitrogen fixing bacteria [11] and phosphate solubilizing microbes [4]. At this juncture, this study is necessary to identify whether herbicide application suppress or enhance/ stimulate the soil microbial population.…”