设计了一种径流观测系统，可以观测表面径流和壤中流。通过观测不同自然降雨和土壤初始条件下的产流产沙过程，揭示了降雨强度较大的情况下，聚土免耕耕作制的产沙强度明显较常规种植的小，说明聚土免耕耕作制防治土壤流失是可行的；但当土壤达到饱和后，聚土免耕的径流强度与常规耕作制常规种植的差异较小，因此，聚土免耕能明显防治径流流失是有限的；水土流失观测小区的坡脚有渗漏阻碍面（墙），不能将表面流和壤中流分开，土壤达饱和后产流发生时，部分壤中流成为地面径流，而所测得的结果与实际的差异较明显，径流偏多而蚀沙偏少。这一点，在建水土流失观测小区时，应足以重视。

A newly designed runoff collection system was used to partition runoff into surface flow and subsurface flow. The analysis of all rainfall runoff generation under different conditions revealed that sediment content of CN tillage system in runoff process is substantially low compared to ST under rainfall with high intensity, showing CN bear the efficient capacity of control soil loss. Nevertheless, when soil is saturated, the runoff intensity of both tillage systems is near, implicating CN has the limited function of reducing runoff. A non-veracity was found that the measured runoff include the both surface runoff and subsurface runoff/return flow for our present observation design of runoff ground with a face or wall of preventing water leaching at down slope end. When saturated runoff generate, the measured soil erosion visibly deviate from the exact response with higher soil and lower water loss.