Evaluation of Water hyacinth and Sugarcane Bagasse Composts as a Carrier for Rhizobium Inoculants and their effects on Faba Bean.

Solid-base inoculants such as peat moss, water hyacinth compost (A), water hyacinth compost (B) (treated with broth yeast culture after composting) and sugarcane bagasse compost as carriers for Rhizobium leguminosarum strain were evaluated. Chemical and physical properties of the carrier materials were performed and total bacteria, actinomycetes and fungi were counted. The effect of these carrier materials on nodulation, growth and yield of faba bean plants was also investigated in field experiment. Inculants made with sterile carriers are preferred, because they contain higher number of rhizobia than those made with non-sterile carrier. In sterile carriers, the compositions of peat and water hyacinth compost (B) were able to maintain the highest and almost the same concentration of rhizobia cells throughout the storage period, while the water hyacinth compost (A) and bagasse compost formulation presented a slightly higher decrease. Moreover, seeds inoculation with the all tested inoculants resulted in significant (0.05 level of P) or highly significant (0.01 level of P) increases in number and dry weight of nodules, shoot and root dry weights, total nitrogen content in shoot, and yields of faba bean, compared with the uninoculated (control) plants. The highest increases were found in plants inoculated either with peat moss or water hyacinth compost (B) inoculants, especially when these carriers were sterilized. The obtained results indicated that water hyacinth compost (B) could be as effective as peat in maintaining high populations of rhizobial and obtaining high plant growth.