| The experiment was conducted on a typical agricultural watehshed-Liu chahe watershed and studied systemically the dynamic change of nutrient in the subsurface with different time and space. The work was begun with the study the dynamic change of nutrient in the farmland and rice field during the plant growth. Then according to the geography character of the watershed as well as rely on the farmland and rice field, much work was conducted on the system of farmland-rice field -pond and farmland-pond to study on the dynamic change of nutriment in different time and different space in the various landscape. The results showed as following(1) with much precipitation and high groundwater level, Liu chahe watershed has a rich subsurface flow whose volume was consistent with precipitation and respond rapidly to the contribution of rainfall.(2) Different treatment and various rainfall hadn't remarkable influence to the phosphorus and nitrogen concentration in time and space in farmland and rice field. This means with long farming, the content of nitrogen and phosphorus in the soil has been saturated. The high concentration of phosphors and nitrogen in subsurface flow in Liu chahe watershed indicated that the subsurface flow may make great contribution to the none point source pollution.(3) In the various landscape, farmland-rice field-pond, both the type of the land and the precipitation are the factors influenced the dynamic change of subsurface flow. But generally the type of the land has the more influence. The plot with the highest cumulative content of nitrogen and phosphorus was in the outside of the rice field which means the restrain role of pond and the double-role of rice field.(4) The high content of nitrogen and phosphorus as well as the more dynamic change of subsurface flow in tomato field and vegetable field indicted that the practice of fertilizer has a strong influence to the content of phosphorus and nitrogen in subsurface flow.
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