濆江流域不同土地利用方式下土壤磷积累特征及流失风险

采用实地采样调查、室内分析与数理统计法研究了濆江小流域耕地、果园、茶园、人工林地、自然林地、饲草地和荒草地7种土地利用方式下表层土壤磷素的积累及吸附特征。结果表明,人工林地、饲草地与耕地土壤全磷>1.0 g·kg-1,呈现积累趋势;饲草地和耕地的Olsen-P≥40.0 mg·kg-1,超过磷素流失临界值;人工林地、饲草地和耕地土壤Ca Cl2-P>4.5 mg·kg-1,也超过磷素流失临界值。茶园土壤吸附固定磷能力极强,耕地、果园地、林地(尤其是人工林地)与草地土壤的吸附固定磷能力较弱。人工林地、耕地与饲草地土壤磷素流失风险较高,宜采用补偿性施磷或维持性磷肥法;果园、荒草地、自然林地的风险较低,茶园土壤磷素几乎无流失风险。

Accumulation and Loss Risk of Soil Phosphorus Under Different Land Uses in Fenjiang River Watershed

Phosphorus(P) is one of the greatest demanded nutrients for crop growth, but unreasonable land use and management are major factors causing non-point source P pollution. This paper examined accumulation and sorption characteristics and potential loss risk of surface soil P under seven land-use types in the Fenjiang River watershed, using field investigation, laboratory analysis, and mathematical statistics. The seven land-use types include farmland(FL), orchard land(OL), tea plantation land(TP), artificial forest land(AF), natural forest land(NL), forage grass land(FG), and weeds land(WL). The content of soil total P in AF, FG and FL were greater than 1.0 g·kg^-1, showing an accumulation trend. In FG and FL, soil Olsen-P content was equal to or higher than 40.0 mg·kg^-1, exceeding the critical value of P loss. The content of soil CaCl₂-P was higher than 4.5 mg·kg^-1 in AF, FG and FL, exceeding the critical value of P loss as well. TP soil had a stronger P sorption and fixation, whereas FL, OL, AF, and FG had a weaker P sorption and fixation, especially AF. The present results show that AL, FL and FG have higher potential risk of P runoff loss and leaching, while OL, WL and NL have a relatively lower risk of P loss. TP soil has almost no P loss risk.