退耕对滇池湖滨土壤理化性质与无机磷分布的影响

目的]明晰退耕对滇池湖滨土壤理化性质和土壤磷素形态分布的影响,进而评价退耕的土壤恢复效应和环境效应。方法]采用空间代替时间的研究方法,对比研究滇池湖滨缓冲带和设施农田剖面土壤理化性质以及无机磷剖面分布特征,并且以滇池湖滨3个区域(牛恋、海埂、兴隆)相同退耕方式为对照进行研究。结果]退耕3a后,牛恋缓冲带浅表地下水埋深明显变浅,土壤有机碳和全氮含量明显增加,土壤全磷,Olsen-P,Al-P和Fe-P含量均明显降低,O-P含量明显增加。但是浅表地下水埋深较深的海埂缓冲带土壤理化性质和无机磷组分没有发生明显变化。兴隆缓冲带土壤有机碳和全氮含量明显降低。3a内退耕没有直接对土壤理化性质和无机磷组分产生明显影响,浅表地下水埋深改变是影响土壤恢复和无机磷组分变化的直接原因之一。结论]滇池湖滨缓冲带和设施农田土壤磷素均存在淋失风险,退耕活动通过抬高浅表地下水位加速土壤磷素淋失从而降低土壤潜在淋失风险。

Effect of Restoration on Soil Physicochemical Properties and Distribution of Soil Inorganic Phosphorus in Dianchi Lake Catchment

Objective] In order to clarify the effect of restoration on soil physicochemical properties and distribution of soil inorganic phosphorus at Dianchi lake catchment, to assess the effects of restoration on soil recover and environment. Methods] The way of space-time substitution was used. Soil physicochemical properties and phosphorus fractions were compared between vegetable field and riparian buffer in soil profile at Dianchi lake catchment. Three areas with similar restoration type were used to compare with each other in the Dianchi riparian. Results] After the 3 years since restored from field, shallow groundwater level was shallower in Niulian buffer than in Niulian field. The content of soil organic carbon and nitrogen were more in Niulian buffer than in Niulian field, the content of total phosphorus, Olsen-P, Al-P and Fe-P were less in Niulian buffer than in Niulian field, the content of O-P was more in Niulian buffer than in Niulian field. The shallow groundwater level in Haigeng buffer was similar to shallow groundwater level in Haigeng field, but compared with Haigeng field, soil physicochemical properties and soil inorganic phosphorus fractions had no significant change in Haigeng buffer. Compared with Xinglong field, content of soil organic carbon and nitrogen decreased significantly in Xinglong buffer. The restoration had no significant effect on soil restoration and soil inorganic phosphorus fractions directly in 3 years. But changing shallow groundwater level had a significant effect on soil physicochemical properties and distribution of soil inorganic phosphorus directly in 3 years. Conclusion] Buffer and vegetable field had risk of phosphorus leaching loss in the Dianchi riparian. Restoration enhanced the speed of phosphorus leaching and reduced potential leaching risk through raising shallow groundwater level.