An investigation on the effects of weeds and calcium cyanamide (CaCN2) fertilizer on number and weight of rhizobium nodules in common bean

Effects of weeds and CaCN2 fertilizer on number and weight of rhizobium nod ules were studied between 1996 and 1998. Based on the average of the three years, number and weight of the nodules were the highest in weed free plots , which was followed by continuously weed free + 60 kg/ha CaCN2, weed cover ed for 15 days, continuously weed free + 40 kg/ha CaCN2, weed covered for 3 0 days, continuously weed covered + 60 kg/ha CaCN2, continuously weed cover ed + 40 kg/ha CaCN2, weed covered for 45 days and continuous weed covered p lots. In continuously weed covered plots treated with 40 or 60 kg/ha CaCN2 the number of nodules and their weight were higher as compared to plots cov ered with weed for only 45 days showing that CaCN2 had an herbicidal effect .