中文摘要：

依托设置于陇中黄土高原雨养农田豆麦双序列轮作系统的保护性耕作长期定位试验，探讨不同耕作措施对土壤物理性状的影响。共设6种耕作措施：T（传统耕作）、NT（免耕不覆盖）、TS（传统耕作＋秸秆还田）、NTS（免耕＋秸秆覆盖）、TP（传统耕作＋地膜覆盖）及NTP（免耕＋地膜覆盖）。结果表明：保护性耕作可降低土壤容重，提升土壤总孔隙度，NTS处理可显著降低0-30cm各土层土壤容重，并显著提升0—30cm各土层总孔隙度和表层土壤饱和导水率；保护性耕作可增大0—30cm各土层机械稳定性和水稳性团聚体含量（≥0．25mm）、平均重量直径（MWD）和平均几何直径（GMD），NTS效果最好；容重和总孔隙度分别与产量呈极显著负相关、极显著正相关，机械稳定性团聚体的含量、MWD和GMD分别与产量呈极显著正相关、显著正相关、显著正相关；水稳性团聚体的含量、MWD和GMD均与产量呈极显著正相关。说明保护性耕作可以改善土壤结构，进而促进作物增产。

英文摘要：

The research work was conducted to explore the effects of conservation tillage on soil physical properties, six types of tillage practices [T （conventional tillage with no straw）, NT （ no-tillage with no straw mulching ）, TS （conventional tillage with straw incorporation）, NTS（ no-tillage with straw mulc- hing）, TP （conventional tillage with plastic mulching）, NTP （no-tillage with plastic mulching）] were con- ducted in a phased rotation system with spring wheat and field pea in rainfed field of the Loess Plateau in cen- tral of Gansu. Results showed that compared with T method, all conservation tillage methods could reduce soil bulk density, increase total porosity, and NTS method was significant in 0-30 cm different soil layer. NTS method could improve soil saturated hydraulic conductivity significantly as well. Compare with T meth- od, in 0-30 cm different soil layer, the aggregates content （≥0.25 mm）, MWD （mean weight diameter）, GMD （geometric mean diameter ） of the mechanical stable aggregates and the water stable aggregates in con- servation tillage methods were better, and NTS method was the best. Soil bulk density had a extremely sig- nificant negatively correlation with crop yields, total porosity however showed a extremely significant posi- tive correlation with crop yields. The aggregates content （≥0.25 mm）, MWD, GMD of the mechanical sta- ble aggregates were extremely significantly positive, significantly positive, significantly positive correlated with crop yields, and all the same three indexes of the water stable aggregates were extremely significantly positive correlated with crop yields. Therefore, with the improvement of soil structure, crop yields would rise.