Soil microbial dynamics as impacted by Diuron, Pyrithiobac sodium and Quizalofop ethyl applied to cotton cultivated in red and black soils
Md Mifta Faizullah, T Ramprakash, T Anjaiah, M Madhavi
Simultaneous two field experiments were conducted during kharif 2018 to study the effect of diuron on soil fungal, bacterial and actinomycetes population dynamics. These experiments were laid out in a Randomized Block Design (RBD) comprising of seven treatments which were replicated thrice. Preemergence herbicides, diuron 80% WP 0.5 kg ha-1, 0.75 kg ha-1 and 1.0 kg ha-1; and pendimethalin 38.7% CS 677 g ha-1 were sprayed two days after sowing. Tank mix application of pyrithiobac sodium + quizalofop ethyl was done at 2-3 leaf stage of the weeds. The non-chemical weed management treatments included polyfilm, mechanical weeding and unweeded control. Soil microbial populations were found to be adversely affected with the application of varied doses of diuron. The higher dose of diuron recorded greater decline in microbial populations. The impact of diuron was more severe in black soils than in red soils on soil bacterial populations. The average percent reduction in fungal population was more in red soil than in black soil. The impact of diuron on actinomycetes population was more severe in black soil compared to red soils at lower rates of application whereas at higher dose, impact was more severe in red soil than in black soil.