Tillage practice and residue management play important roles in N pool in soils. This study determined the impacts of tillage practice and residue management on crop yield. It also investigated the distribution, fractionation, and stratification of N at soil at depths ranging from 0 to 60 cm under wheat–maize cropping systems. Three treatments were established in 2009: no-tillage with straw removal for winter wheat and summer maize (NT), no-tillage with straw mulching for winter wheat and summer maize (NTS), no-tillage with straw mulching for summer maize and plow tillage with straw incorporation for winter wheat (NPTS). After 8 years, soil total nitrogen (TN) content in NTS was greater than in NT, but only in 0–10 cm layer. NPTS treatment increased TN content over NT and NTS in 10–20 cm layer by 18.0% and 13.9%, and by 16.8% and 18.1% in 20–30 cm layer, respectively. Particulate organic N, microbial biomass N and water-extractable organic N levels were the greatest in 0–10 cm layer under NTS treatment; and in 10–30 cm layer, the corresponding values were the highest under NPTS treatment. NPTS treatment could immobilize the mineral N in 10–30 cm layer, and reduced leaching losses into deeper soil layers (40–60 cm). Furthermore, total yield increased by 14.7% and 8.5% in NPTS treatment compared to NT and NTS treatments, respectively. These results indicate that NPTS is an effective and sustainable management practice, which will improve soil fertility, sustainable crop production, and environmental quality in low-productivity soils in central China.
农耕措施和秸秆处理对土壤氮素管理有重要影响。本研究测定了不同农耕措施和秸秆处理下小麦-玉米种植系统中 0-60 cm深度土层中氮的分布、形态分析和分层情况，并探讨了对作物产量的影响。实验于 2009 年进行，设置了三种处理：冬小麦-夏玉米免耕无秸秆（NT）、冬小麦-夏玉米免耕秸秆覆盖 （NTS）、冬小麦-夏玉米免耕秸秆还田（NPTS）。8年后测定相关数据，NTS处理土壤全氮 （TN）含量仅在0-10 cm土层大于NT处理；相较于NT处理和NTS处理，NPTS处理使10-20 cm土层中的TN含量分别增加了18.0％ 和13.9％，20-30 cm土层中的TN含量分别增加了16.8％ 和18.1％。在NTS处理下，0-10cm土层中有机氮、微生物生物量氮和水可提取有机态氮含量最高；在10-30 cm土层中则是NPTS处理下最高。NPTS处理中，矿物氮被固定在10-30cm的土层中，并更少地浸出损失到更深的土层（40-60 cm）。此外，与NT和NTS处理相比，NPTS处理中作物总产量分别增加了14.7％ 和 8.5％。这些结果表明，NPTS是一种有效和可持续的管理措施，能够改善中国中部低生产力土壤的肥力状况，实现可持续的作物生产和环境质量保障。
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