覆盖与灌溉条件下农田耕层土壤养分含量的动态变化

试验于2002-2003年在中国科学院地理所禹城综合试验站进行，研究了秸秆覆盖和灌溉相结合条件下冬小麦-夏玉米一年两熟农田耕层土壤有机质及速效养分含量的动态变化．结果表明：秸秆覆盖对提高土壤有机质含量有重要作用。不覆盖农田中，灌溉可降低有机质含量。而覆盖农田中，这种降低作用不显著。在冬小麦生育期间，灌溉可使碱解氮的含量下降．覆盖处理下降的程度更大。秸秆覆蓝可明显提高速效磷的含量，灌溉可使其含量进一步增加。秸秆覆盖可明显提高耕层内速效钾的含量，夏玉米生育期间．灌溉处理速效钾含量升高。

Dynamic Variety of Soil Nutrient Content Under Conditions of Straw Mulching and Irrigation

The experiment was conducted at Yucheng comprehensive experimental station to study dynamic variety of soil organic matter and available nutrient content in winter wheat and summer maize a year under the conditions of straw mulching and irrigation in 2002-2003, the results showed it was important for straw mulching to increase organic matter in winter wheat and summer maize a year planting system. Under the conditions of without straw mulching, irrigation could decrease organic matter content, but under the conditions of straw mulching, the effects were unobviously. In growth stages of winter wheat, irrigation could decreased alkali-hydrolyzable. N content, and straw mulching could decrease the content greatly, the reason for this was eluviation. Available P was increased greatly under the conditions of straw mulching, and irrigation could increase the content greatly. Available K was increased greatly under the straw mulching conditions. In growth stage of summer maize, the treatments which irrigated in winter wheat growth stages could increase Available K content greatly.