中文摘要：

【目的】在旱区农业生产中,保护性耕作因具有保持水土、增产增收的优点而受到广泛关注,但其效应因地域环境、气候条件和栽培体系而异。本研究比较了半湿润易旱区旋耕垄作、免耕和免耕覆盖3种保护性耕作方式对夏玉米产量及水、氮利用效率的影响,为本地区筛选优化保护性耕作方式提供技术支撑。【方法】试验于2014年和2015年6~10月份在陕西关中地区进行。采用裂区试验设计,主区为旋耕垄作（RT）、免耕（NT）和免耕覆盖（NTM）3种保护性耕作方式;副区为施氮（N230）和不施氮（N0）2个施氮处理。【结果】1）与免耕和旋耕垄作相比,免耕覆盖处理可提高夏玉米耕层土壤生育期内含水量,降低高温季节耕层土壤温度,具有显著的增产效应,两年籽粒产量平均值的增幅分别为13.2%和41.8%;2）与旋耕垄作相比,免耕和免耕覆盖处理可显著降低夏玉米耗水量、增加地上部吸氮量,提高夏玉米的水、氮利用效率。其中,免耕和免耕覆盖的水分利用效率较旋耕垄作分别显著增加7.1和10.3 kg/（hm2·mm）,氮肥利用率分别增加3.8百分点和10.1百分点;3）与不施氮相比,施氮能够促进夏玉米生长,提高地上部吸氮量、产量及水分利用效率,施氮各处理籽粒产量和水分利用效率的平均值较不施氮处理显著提高49.5%和50.5%。【结论】免耕和免耕覆盖尤其是免耕覆盖可有效调节土壤水热变化,解决本地区夏玉米生产中苗期干旱少雨导致的土壤水分匮乏问题,提高夏玉米籽粒产量及水氮利用效率。

英文摘要：

[ Objectives ] Conservation tillage has been received wide attention in agriculture of arid and semiarid regions due to its advantages in conserving soil and water and increasing yield. But its effects vary owing to landscapes, climate condition and cultivation system. The aim of the study was to investigate the adaption of three conservation practices in the semi-humid and sensitive to drought area and to provide theoretical basis and technical foundation for selection and optimum of conservation tillage practices in similar areas. [ Methods ] The experiment was conducted in Guanzhong Plain, Shaanxi, China from June 2014 to October 2015. The field experiment was in a split-plot design, and three tillage methods, rotary and ridge tillage （RT）, no-tillage （NT） and no-tillage with straw mulching （NTM） were assigned to the main plot and nitrogen levels （N230 and N0） were the subplot. [ Results ] 1） Compared to the NT and RT treatment, the average moisture contents in the cultivation layer （0-20 cm） of the NTM treatments in summer maize growing season were increased, the temperature was decreased and yields were increased significantly, and the average yields of the NTM treatments in the two years were increased （P〈0.05） by 13.2% and 41.8% respectively. 2） The NT and NTM treatments could cut down water consumption, increase the amount of nitrogen uptake and improve the water and nitrogen use efficiencies of summer maize significantly. Compared to the RT treatment, the water use efficiencies of the NT and NTM treatments in the 2 years were increased by 7.1 and 10.3 kg/（hm2.mm） （P〈0.05）, respectively, and the nitrogen use efficiencies were increased by 3.8 and 10.1 percentage points （P〈0.05）, respectively. 3） Compared with the NO treatment, the N230 treatment could promote growth of summer maize, and increase the amount of nitrogen uptake, grain yield and water use efficiency. The average of grain yield and water use efficiency for the N230 in the two years were increased