桃江流域农业区氮平衡及时空差异性

Nitrogen Balance and Its Space-Time Difference of Agricultural Region in Tao River Basin

针对桃江流域农业区氮平衡及其时空差异性问题,建立了氮平衡模型,基于该模型计算了2006～2008年桃江流域内各行政区(县)的氮平衡变化,并汇总得到流域内氮的输入量、输出量及剩余量。结果表明,2006～2008年间,氮总输入量分别为31 935、33 162、33 878t/年,年增长率分别为3.8%、2.2%,呈明显上升趋势,各种氮的输入中化肥施用占44.94%、人畜粪便返田占26.06%、生物固氮占13.91%、大气沉降占11.59%、秸秆返田占3.50%,化肥施用占明显优势;氮总输出量分别为18 109、17 982、19 048t/年,年增长率分别为-0.7%、5.9%,整体呈微幅上升趋势,各种氮的输出中作物收获占49.36%、反硝化占27.99%、氨挥发占22.65%,作物收获占明显优势;氮的剩余量分别为13 827、15 180、14 830t/年,年增长率分别为9.8%、4.3%,呈显著上升趋势。桃江流域所在的5个县中,信丰县氮剩余量占流域氮总剩余量的41%以上,且呈增长趋势,因此信丰县为桃江流域农业区氮污染重点防治区。

In view of the Nitrogen balance and its space-time difference of agricultural region in Tao River Basin, Nitrogen balance model is established. Nitrogen balance changes in all districts of Tao River Basin are calculated with the model. Meanwhile, inputs, outputs and surpluses of Nitrogen in the whole basin are obtained. The results show that Ni- trogen inputs from 2006 to 2008 obviously appears rising trend; the total Nitrogen inputs are 31 935, 33 162 and 33 878 t/a, respectively; annual growth rates are 3.8% and 2.2% ; in each of Nitrogen inputs, chemical fertilizer accounts for 44.94 %; human and animal excreta accounts for 26.06% ; biological nitrogen fixation accounts for 13.91% ; atmospheric deposition accounts for 11.59 % ; crops residue to soil accounts for 3.50 % chemical fertilizer has obvious dominance; the total Nitrogen outputs are 18 109, 17 982 and 19 048 t/a; annual growth rates are -0.7%and 5.9%; it is little rising trend; in Nitrogen outputs, harvested crops accounts for 49.36%; denitrification accounts for 27.99%; the total ammonia volatilization accounts for 22.65%; harvested crops has obvious dominance; in Nitrogen surpluses of the whole basin are 13 827, 15 180 and 14 830 t/a; annual growth rates are 9.8% and 4.3%; it obviously appears rising trend; Nitrogen surpluses of Xinfeng City accounts for 41% of the whole five districts in Tao River Basin and it appears rising trend; therefore, Xinfeng City is the major prevention and control region of the nitrogen pollution of agricultural region in Tao River Basin.