nitrogen turnover to improve cropping yield in sustainable agriculture using 15N technique

organic matter of leucaena cuttings, soybean straw, and rice straw inoculated with micro-organisms of aspergillus terreus and azotobacter chroococum proved efficient sources for n turn-over and mineralization especially leucaena which gave the highest mineralization . rice straw gave lowest mineralization . in the inoculation experiment,the highest contents of mineralized N occurred after about 30 day following inoculation of the sand soil containing these organic material . inoculation was superior to no-inoculation between day 15,and day 45, when the Az and (As+Az)surpassed the non-inoculated, and was most effective with rice straw. the superiority of Az over As in producing mineral N from the organic N was most prominent where rice straw was the source. leucaena was more efficient than a considerable superiority rice straw and soybean straw, due to its high N content , and apparently due to rapid decomposition and high C/N ratio. superiority of soybean over rice straw was slight where Az was used As inoculants