Evaluating Optimum Nitrogen Management Associated with Production and Environmental Load of Farm-Systems in the Dahuofang Reservoir Region

摘要

N budgets analysis model offers a new set of tools for evaluating the N cycling in Agricultural systems. Cycling Index (CI) is also a useful tool for estimating optimal N flows in farms and Application Index (AI) as a good indicator for characterizing the N flows in farms. Using these parameters, we analyzed all farm-systems to estimate the optimal N Management for safety N pollution in ground water and maximizing N export in the Dahuofang Reservoir region. It was clearly shown the critical N application rate (chemical fertilizer + manure) was 208.4 kg N ha 1 y 1. The critical inter-system input (application N, imported food and feed N and natural supplied N) was 422.5 kg N ha 1 y 1.