中文摘要：

以子午岭连家砭林场不同退耕年限草地为研究对象,以撂荒地为对照,通过野外调查和室内测试分析,研究了退耕12 a、18 a、24 a、36 a草地土壤分离速率及其理化性质。结果表明：草地土壤分离速率与同一土层的撂荒地相比明显降低,并随着退耕年限增加而降低。不同退耕年限草地土壤容重、有机质含量、水稳性团聚体含量、根系生物量密度均有不同程度的改变,且表层土壤（0-20 cm）理化性质改善最为显著（P〈0.05）;不同退耕年限草地土壤分离速率与其理化性质均呈显著相关关系（P〈0.05）,但对于不同退耕年限草地,影响土壤分离速率的主导因子不同。

英文摘要：

In order to survey the effect of grain for green on soil physiochemical properties and erosion resistance, 4 types of grasslands （after implementing the project of grain for green for 12,18,24 and 36 years respectively） and an abandoned field as the control in Lianjiabian Forestry Center were chosen as the sample plots. The soil detach- ment capacity and soil physiochemical properties were tested in laboratory. The results showed that the soil detach- ment rate in the 4 in soil layer of 40 types of grasslands was lower than that in the abandoned field in the same soil layers except that -60 cm in depth in the grassland after implementing the project. The data also showed that the soil detachment rate was decreased with the increase of years of grain for green. Among the sample plots with differ- ent years after implementing the project of grain for green, the soil bulk density, soil organic matter content, soil wa- ter stable aggregate content and root weight density varied in different degrees. Compared with the subsurface soil layers （20 -40 cm） or the bottom soil layers （40 -60 cm）, the variation of physiochemical properties of topsoil （0 - 20 cm） was the most significant （ P 〈 0.05 ）. The soil bulk density increased significantly, however, the soil organic matter content, water stable aggregate content and root weight density decreased prominently with the in- crease of soil depth in the same sample plots. The soil bulk density was positively correlated with soil detachment rate （ P 〈 O. 05 ） , the correlation coefficient varied in a range of 0. 497 - 0.828. The soil organic matter content, soil water stable aggregate content, root weight density were all negatively correlated with soil detachment rate （P 〈 0.01 ） , their correlation coefficient were - 0.309 - - 0.813, - 0. 348 - - 0.761 and - 0. 544 - - 0.731 respec- tively. According to this study, the key factor affecting the soil detachment rate was not determined yet, and more studies will be needed.