华北太行山前平原农田生态系统中氮、磷、钾循环与平衡研究

以栾城县为例，分析了华北太行山前平原农田生态系统N、P、K三要素养分循环与平衡特征及其变化趋势，评价了农田养分平衡状况，提出了合理施肥对策。结果表明，1985～2000年栾城县农田养分平衡中，N素经历了由轻微赤字向盈余的转变过程，由1985年的1．4％赤字转变到2000年盈余48．6％；K由极度亏缺(82％赤字)，逐渐向平衡发展，到2000年已有4．6％的轻微盈余，但仍有大量田块是赤字平衡；P则始终有大量盈余。目前农田养分收支存在一定程度的N、P投入过量，K投入不足的问题，以土壤肥力状况和作物种植结构而论，栾城县应采取“稳氮、控磷、增钾”的施肥对策。避免过多的盈余化肥氮进入环境，同时应继续推广秸秆还田技术，提高养分循环再利用效率。

Nitrogen, phosphorus and potassium cycling and balance in farmland ecosystem at the piedmont of Taihang

The feature and change trend of N, P and K cycling and balance in farmland ecosystem of Luancheng County at the piedmont of Taihang were analyzed. The status of nutrient balance was appraised, and the rational way to apply fertilizer was put forward. The result indicated that N balance went through a process from slight deficit to surplus during 1985-2000, changing from deficit of 1.4% in 1985 to surplus of 48.6% in 2000. Potassium balance changed gradually from serious deficit of 82% to slight surplus of 4.6%, but was still deficit in many fields. P budget was surplus ever since 1985. Comparing with the output of nutrients, the inputs of N and P were excessive, but the K input was short. Under the current soil fertility and crop planting structure, the countermeasure to control the application amount of N and P and to increase the application rate of K should be carried out, so that, there would be no significant surplus N emitting or leaching from soil into environment. The technique to return crop straw into farmland should be extended to increase the nutrient recycling rate.