摘要： 应用¹⁵N示踪技术研究了塑膜覆盖生态系统中肥料氮的循环。结果表明, 在覆盖及玉米秸秆还田条件下氮的18.56％被第一季玉米所吸收, 59.09％残留在土壤中。第二季小麦和第三季夏谷又分别回收秸秆氮4.0％和2.9％。玉米对硫酸铵氮的利用率为38.4％, 其中15.8％分布在茎叶和根茬中, 参与养分再循环, 但氮素损失大, 接近施肥量的50％。残留在土壤中的秸秆氨3.4％存在于未分解的秸秆中, 3.5％移动到土壤下层（30～50cm）, 45.8％与土壤矿物结合。化肥氮残留很少, 大部分进入土壤有机无机复合体中, 而部分土壤氮被活化。

关键词: 氮, 覆盖, 循环, 残留, 有机无机复合体

Abstract: ¹⁵N was used to study the cycling of fertilizer N in the ecosystem of film mulching. Results showed that 18.56% of the N in the corn stalks, returned to the field under the conditions of film mulching, was absorbed by the first crop corn, while 59.09% was left in the soil. The second crop wheat and the third crop summer millet absorbed 4.04% and 2.89% of the stalk N respectively. Corn utilized 38.44% of the ammonium sulfate, of which 15.80% was distributed among the stems, leaves and roots, participating in the recycling of nutrients. But, in this way, the loss of N was rather great, amounting to about 50% of the N input.3.4% of the stalk N residue left in the soil was in the undecomposed stalk while 3.5% moved to the lower stratum(30-50cm), and 45.8% was combined with soil minerals. There was very little fertilizer N residue left, most of which entered the organo-mineral complex, while a part of the soil N was activated.

Key words: Nitrogen, Mulching, Cycling, Residue, Organo-mineral complex