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

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

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。

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 Ca Cl2-P was higher than 4.5 mg·kg-1in 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.