| 摘要: |
| 【目的】研究滇池周边不同土地利用方式下土壤基本理化性质和土壤总磷（TP）、有效磷（Olsen-P）、水溶性磷（Water P）含量在不同土层（0～20，20～40，40～60，60～80，80～100 cm）变化状况及其磷吸附特性，旨在阐明农田土地利用方式对滇池流域土壤磷流失的潜在影响。【方法】2009年，在滇池流域选择常规水稻 蚕豆轮作、露地蔬菜、3～5年和10年以上塑料大棚4种土地利用方式下的农田作为研究对象，采集0～100 cm土层的土样，测定土壤基本理化性质和不同形态磷含量，用Langmuir方程拟合不同土地利用方式下土壤的磷吸附特性，并对土壤基本理化性质及不同形态磷含量与土壤磷素吸附特征参数土壤磷最大吸附量（Smax）和土壤磷吸附能常数（k）相关性进行分析。【结果】不同土地利用方式对不同土层土壤基本理化性质有明显影响。4种土地利用方式下，农田土壤TP、Olsen-P和Water-P主要积累于土壤表层（0～20 cm）。与常规水稻 蚕豆轮作地相比，露地蔬菜地、10年以上塑料大棚和3～5年塑料大棚表层（0～20 cm）土壤的Olsen-P含量分别高达89.86，74.93，45.07 mg/kg，均超过土壤磷向周围水体流失的“突变点”。4种土地利用方式农田的Smax和k分别为747～1 533 mg/kg和0.08～0.75 L/mg，其中露地蔬菜地、3～5年和10年以上塑料大棚表层（0～20 cm）土壤的Smax较水稻 蚕豆轮作地显著降低，k值则随土层深度的增加及塑料大棚种植时间的延长而增大；Smax和k与不同土地利用方式下土壤全氮、NH4+-N、NO3--N含量及C/N呈显著相关关系，Olsen-P和Water-P含量与k呈显著负相关关系（k分别为-0.49和-0.52，P<0.05）。【结论】农田土地利用方式由水稻 蚕豆轮作向集约化蔬菜、花卉生产转变，将会引起土壤特性改变、磷素积累及降低土壤对磷吸附，使农田土壤磷向周边水体流失从而增加水体富营养化的环境风险。 |
| 关键词: 滇池流域 土地利用方式 磷 吸附 面源污染 |
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| 基金项目:云南省科技厅省院省校科技合作项目（2006YX35）；昆明市科技局项目（08S010201) |
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| Effects of land use type on phosphorus accumulation and absorption characteristics of farmland soil in Dianchi Lake Watershed |
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| Abstract: |
| 【Objective】This paper studied the changes of soil basical physicochemical properties and total phosphorus (TP),available phosphorus (Olsen-P),water-soluble phosphorus (Water-P) and phosphorus absorption characteristics in different soil layers (0-20,20-40,40-60,60-80 and 80-100 cm) among the different land use types surrounding Dianchi Lake,and aimed to understand the potential influence of phosphorus loss from farmland soil in land use patterns in the Dianchi Lake Watershed.【Method】In 2009,four representative land use types were selected,i.e.,conventional rice-broad bean rotation field,open vegetables field,3-5 years plastics covered greenhouse field,and >10 years plastics covered greenhouse field.20 soil samples of 0-100 cm soil layer were collected and their physical and chemical properties and different forms of phosphorus contents were determined,and the parameters of phosphorus absorption characteristic:phosphorus maximum sorption (Smax) and constan constant of phosphorus binding energy (k) were obtained by Langmuir equation fitting.And the correlation relationships between soil basic physicochemical characteristics,contents of different forms of P and Smax,k were analyzed.【Result】The results indicated that land use could obviously influence soil basic physicochemical properties,and the accumulation of TP,Olsen-P and Water-P mainly occurred in surface soil (0-20 cm) of farmland soil.Compared with rice-broad bean rotation,soil Olsen-P contents of open vegetables,>10 years plastics covered greenhouse and 3-5 years plastics covered greenhouse field reached 89.86,74.93,45.07 mg/kg,respectively,and they were beyond “change point” of soil phosphorus losses to water body by runoff.The Smax and k of four land use types ranged from 747 to 1 533 mg/kg and from 0.08 to 0.75 L/mg,respectively.The Smax of three vegetables and flowers production field significantly reduced at surface soil (0-20 cm) besides rice-broad bean rotation,and as soil depth deepened k values increased with the increasing year of plastic covered greenhouse production of four land use types.Many correlations between contents of soil total Nitrogen,NH4+-N,NO3--N and ration corbon to nitrogen and nitrogen and Smax and k were found.Olsen-P and Water-P contents correlated with k was a significant negative relationship (r was -0.49 and -0.52,respectively,P<0.05).【Conclusion】The transform of land use type of farmland from conventional rice-broad bean rotation to intensive vegetables or flower production lead to change soil properties and to reduce phosphorus adsorption ability,and the risk of farmland soil phosphorus loss to surrounding water body is increased. |
| Key words: Dianchi Lake Watershed landuse type phosphorus absorption non point source pollution |
