The study was conducted at G.B. Pant University of Agriculture and Technology, Pantnagar during rainy seasons of 2012-13 and 2013-14 to evaluate the efficacy of halosulfuron 12% + metribuzin 55% WG ready-mix (RM) coded as CPL-1255 in sugarcane, and its carry over impact on succeeding lentil. The maximum weed suppression and the highest weed control efficiency were obtained with application of halosulfuron + metribuzin (RM) at higher doses (600 and 900 g/ha) applied as post-emergence, and were significantly better than the alone application of atrazine 50% WP and 2,4-D amine salt 50% SL at recommended doses. Combination of halosulfuron + metribuzin (RM) even applied at 600 g/ha was also found superior over atrazine 50% WP at 2000 g and 2,4-D amine 58% SL at 3500 g/ha while execution of twice hoeing (30 and 60 day after planting (DAP)) was also comparable to combination of halosulfuron + metribuzin at lower and higher doses at 450 and 900 g/ha, respectively, during 2012 and only to lower dose during 2013 with respect to cane yield. The ready mix application of halosulfuron + metribuzin at any dose did not pronounce any phytotoxic effect on sugarcane as well as carry over effect on the succeeding lentil in respect to germination, growth and grain yield. Overall microbial population was higher before application and decreased after application of herbicide at harvest. Herbicidal treated plots had no significant effect on bacterial counts. There was drastic reduction in microbial population at 7 day after application (DAA) of herbicide and increased thereafter. At harvest overall population of actinomycetes varied from 43.7% to 20.1% over weedy check.