| In order to clarify the effect of restoration on soil physicochemical properties and distribution of soil inorganic phosphorus at Dianchi Lake’s catchment, to assess the effects of restoration on soil environment. Three areas (Niulian, Haigeng, Xinglong) were studied in the Dianchi riparian. Soil (0-100cm) were sampled at the three areas, and shallow groundwater was just sampled at Niulian. Soil profile physic-chemical properties and phosphorus fractions were compared between the farm and buffer at Dianchi lake’s riparian. The result showed that:1. With the riparian extends from south to north in sampling areas, soil texture has become coarse, soil texture is clay in Niulian, and loamy clay in Xinglong. But soil texture had no significant difference between buffer and farm in the same site. This indicated that soil texture in these areas had been affected by the topography but restoration of buffer strip. The content of soil organic carbon and nitrogen were more in buffer than in farm in Dianchi riparian. Soil pH and density had no significant difference between buffer and farm in Dianchi riparian.This indicated that after the3years since restored from farm, restoration had effect on soil physicochemical. But the content of soil organic carbon and nitrogen had difference between buffer and farm in three locates. And the content of soil organic carbon and nitrogen were more in Niulian buffer than in Niulian farm. Compared with Haigeng farm, soil physicochemical properties had no significant change in Haigeng buffer. Compared with Xinglong farm, content of soil organic carbon and nitrogen decreased significantly in Xinglong buffer. Soil density was negatively correlated to content of soil organic carbon. The content of soil organic carbon was negatively correlated to shallow groundwater depth. This indicated that shallow groundwater level had a significant effect on soil physicochemical properties. Soil physic-chemical properties differed significantly between the farms and buffers. The effect of restoration of buffer strip on soil properties may be caused by the changes of shallow groundwater level.2. The content of soil total phosphorus and Olsen-P were more in farm than in buffer in Dianchi riparian. This indicated that restoration had effect on the content of phosphorus and availability of phosphorus. The content of soil inorganic phosphorus fractions had no significant difference between farm and buffer in Dianchi riparian. This indicated that after the3years since restored from farm, restoration had no significant effect on soil inorganic phosphorus fractions. But the content of soil inorganic phosphorus had significant difference between buffer and farm in three locates. The content of soil Al-P, Fe-P and Ca-P were more in Niulian farm than in Niulian buffer. And content of soil O-P were less in Niulian farm than in Niulian buffer. Compared with Haigeng farm, soil content of inorganic phosphorus had no significant change in Haigeng buffer. The content of soil O-P and Ca-P were more in Xinglong farm than in Xinglong buffer, this because that content of organic carbon was more in Xinglong farm than in Xinglong buffer. And content of soil Al-P, Fe-P had no difference between Niulian farm and Niulian buffer. The change of soil Olsen-P, Al-P and Fe-P were similar to the change of shallow groundwater depth. The shallow groundwater depth was shallower, and the content of soil Olsen-P, Al-P and Fe-P were less. This indicated that soil organic and depth of shallow groundwater had effect on distribution of inorganic phosphorus. Restoration result in shallow groundwater depth changing, and soil redox condition changing, and phosphorus was restored resulted in leaching. The regression analysis indicated that Al-P〠pH and O-P can present50%Olsen-P change. Soil Al-P, Fe-P, O-P and TP were concentrated in clay. The content of Ca-P was very high, but had no significant differences in different fractions particle size. Recovered from farm had effect on the distribution of inorganic phosphorus in soil particle size. Fe-P was concentrated in silt of farm, but Fe-P was concentrated in clay of buffer. This indicated that restoration of buffer strip influcenced the distribution of soil phosphorus in different particle size. Restoration has resulted in the reduction of inorganic phosphorus concentration in sand size. However, concentration of inorganic phosphorus in clay did not differed significantly between the farms and buffers.3. Shallow groundwater COD was correlated positively with soil organic carbon. Shallow groundwater nitrate was correlated positively with soil total nitrogen. Shallow groundwater EC was correlated positively with soil EC. This indicated that soil nutrient had effect on shallow groundwater relevant composition through leaching. The groundwater depth was one of factors that effect on soil nutrient leaching. There was significant correlation between shallow groundwater level and total phosphorus concentration groundwater as well as COD concentration.Surface soil Olsen-P, Al-P and Fe-P concentrations were correlated inversely with total phosphorus concentration of groundwater respectively. This indicated that surface soil was the main layer where phosphorus leaching took place, and shallow groundwater level has a significant effect on soil phosphorus leaching at the riparian of Dianchi lake. The increase of groundwater level caused by restoration of buffer strip may enhance soil Al-P and Fe-P leaching, thereby deteriorate contamination of Dianchi lake. |
