The influencing factors of soil anti-scouribility of tree-crop intercropping land in purple soil hilly region

Chinese. 研究土壤抗冲性的影响因素。采用原状土冲刷试验及室内土壤理化性质分析的方法，对紫色丘陵区农林混作模式的土壤抗冲性影响因素进行研究。（1）容重与土壤抗冲指数呈正相关，总孔隙度与土壤抗冲指数呈负相关。在短历时高强度的冲刷条件下，紫色土的土壤容重越大，孔隙度越小，土壤越紧实，其抗冲性能越强；（2）土壤抗冲指数与细砂粒（0.25～0.05 mm）含量呈显著正相关且表现为指数函数关系，说明较粗颗粒的存在有助于提高土壤抵抗径流冲刷的能力；（3）＞5 mm水稳性团聚体与土壤抗冲指数呈极显著正相关，＞0.25 mm水稳性团聚体与土壤抗冲指数呈显著正相关，大粒径水稳性团聚体含量越高，土壤结构越好，土粒越不易被径流冲散，土壤抗冲性能越强；（4）土壤抗冲指数随稳渗率、初渗率呈线性变化，分别呈极显著正相关和显著正相关；（5）不同径级根系生物量均与土壤抗冲指数呈极显著正相关，根密度与土壤抗冲指数呈显著正相关，＜3 mm根系长度与土壤抗冲指数也呈显著正相关；根系的存在有效地提高了土壤抗冲性。土壤容重、细砂粒含量、＞5 mm水稳性团聚体含量、稳渗率、＜1 mm根系生物量可用于该地区土壤抗冲性的预测和评价。

English. The objective of this research was to study the influencing factors of soil anti-scouribility. With the methods of undisturbed-soil trough scouring and soil physical and chemical properties analysis indoor, the influencing factors of soil anti-scouribility of tree-crop intercropping land in purple soil hilly region were studied systematically. (1) Soil bulk density had remarkable positive correlation with the index of soil anti-scouribility and soil porosity had remarkable negative correlation with the index, and this result showed that the larger the soil bulk density, the small the soil porosity, and the soil will be more solid, the soil anti-scouribility will be improved under the short time and high intensity washing condition; (2) The fine sand (0.25-0.05 mm) content had remarkable positive correlation with the index of soil anti-scouribility, and which showed that the coarse granule could enhance soil anti-scouribility; (3) The ＞5 mm water stable aggregates content had great remarkable positive correlation with the index of soil anti-scouribility and the ＞0.25 mm water stable aggregates content also had remarkable positive correlation with the index, which showed that the more the big water stable aggregates content, the finer the soil structure will, the soil anti-scouribility will be enhanced ; (4) The steady water infiltration rate had a great remarkable positive linear correlation with the index of soil anti-scouribility and the initial water infiltration rate also had a remarkable positive linear correlation with the index; (5) The root biomass in different diameters all had great remarkable positive correlation with the index of soil anti-scouribility, and the root density had a remarkable positive correlation with the index of soil anti-scouribility, the root length of ＜3 mm root also had a remarkable positive correlation with the index of soil anti-scouribility. The root system can enhance soil anti-scouribility effectually. Soil bulk density, fine sand（0.25-0.05 mm）content, ＞5 mm water stable aggregates content, steady water infiltration rate and the root biomass of ＜1 mm root can be used to forecast and evaluate the purple soil anti-scouribility in this area.