Effect of Pendimethalin on Rhizobial Efficiency in Soybean (Glycine max. (L.) Merrill)

A field experiment was conducted during kharif 1992 and 1993 on a loamy sand soil to study the effect of recommended herbicide (pendimethalin) on the efficacy of rhizobial inoculant determi ned by nodulation, nitrogenase activity, biological nitrogen fixation (BNF), growth and yield of soybean cv. PK 416. Results revealed that application of pendimethalin 0.5 kg/ha neither had any adverse effect on the nodulation and nitrogenase activity nor it influenced the efficiency of rhizobial inoculants in terms of BNF in soybean during any year. Rhizobium inoculation irrespective of the mode of weed control (chemical or manual) enhanced the BNF and fixed an additional 66.1–74.7 kg N/ha over uninoculated control, thereby increasing the seed yield of soybean significantly by 8.2 and 12.2 per cent during 1st and 2nd year, respectively.