Effect of sequential application of herbicides on microbial activities and yield of maize

A field experiment was conducted at Main Agricultural Research Station (MARS), Agriculture College, Dharwad to study the effect of sequential application of herbicides on microbial activities and yield of maize. Six herbicides, namely, glyphosate, paraquat, glufosinate ammonium, saflufenacil, halosulfuron and imazathapyr were tried as post-emergence in addition to pre-emergence application of atrazine. Totally nine treatments were tested using randomized block design having three replications with three controls [Weedy check, weed free check and standard recommended package of practices (RPP)]. Weed free check was recorded higher weed control index (WCI) than rest of the weed control methods at all the growth stages of maize. However, the treatment, pre-emergence application of atrazine @ 1 kg/ha fb post-emergence application of glyphosate @ 2.5 kg/ha recorded WCI of 92.12% next to weed free check. Weed free check recorded significantly higher grain yield (84.59 q/ha), stover yield (114.10 q/ha) and harvest index (42.57%). At different growth stages of maize, both pre- and post-emergence applications of herbicides, all the enzymatic activities in the soil were reduced as compared to untreated plots.