Research on Nitrogen Budgets of Agricultural Fields of the Tao River Basin

摘要

Based on a nitrogen (N) budget change model of agricultural fields, nitrogen budget change in each county in Tao River basin was calculated. For the whole basin, N-inputs, N-outputs and N-surpluses were obtained. The results indicated that N-inputs and N-outputs of Tao River from 2006 to 2008 increased obviously. The total N-inputs (N-outputs) in 2006, 2007 and 2008 were 31935 (18109) Tg, 33162 (17982) Tg and 33878 (19048) Tg, respectively. Compared the sources of N inputs, chemical fertilizer accounted for 44.94%, followed by human and animal excreta with 26.06%. For the N-outputs, the percent of crop harvest was biggest with 49.36%. N surpluses were 13826 Tg yr~(-1) in 2006, 15179 Tg yr~(-1) in 2007 and 15829 Tg yr~(-1) in 2008g. Annual growth rates were 9.9% in 2007 related to 2006 and 4.3% in 2008 related to 2007. The N-budgets with positive values showed that it increased significantly. Therefore, it was very urgent to control the non-point source of nitrogen pollution in Tao River basin.