秦岭北麓两种土地利用下土壤磷素淋溶风险预测

Prediction of Soil Phosphorus Leaching Risk Under Two Types of Land Use in Northern Area of Qinling Mountains

鉴于猕猴桃、小麦-玉米轮作两种土地利用的施肥差异和磷素的环境风险,研究秦岭北麓两种利用方式下塿土磷素的淋溶风险与差异。测定两种利用耕层(0~20 cm)和剖面(0~100 cm)土壤Olsen-P、CaCl2-P含量,用耕层土壤Olsen-P、CaCl2-P作图预测磷素淋溶'突变点',分析两种利用方式土壤剖面CaCl2-P与Olsen-P含量的变化趋势和CaCl2-P的变化特征。得出猕猴桃园土壤磷素肥力较好,42.63%的果园土壤Olsen-P含量充足,达到丰产优质需求(60.90~79.60 mg·kg-1),96.43%的农田土壤Olsen-P含量低于大田作物高产适宜含量(20 mg·kg-1),平均值处于四级肥力水平。猕猴桃园磷素淋溶'突变点'对应的Olsen-P含量为40.11 mg·kg-1,有62.79%的果园土壤会发生磷素淋溶,淋溶风险较大;农田土壤磷素累积少,没有明显的淋溶'突变点',但多年的耕作使其也有微弱的淋溶发生。两种利用下土壤磷素的淋溶深度为40 cm,需要采取一些措施解决优质丰产与磷素环境风险的矛盾。

Soil phosphorus(P)leaching has been considered to be a critical cause of water eutrophication. Phosphorus leaching risks in Lou soil under two kinds of land use, kiwi-fruit orchard and arable land, in the northern area of Qiling Mountains were studied. The samples included surface layer(0~20 cm)samples of 43 kiwi orchard and 28 arable land and three profile(0~100 cm)samples of two types of land use. In general, soil phosphorus contents were higher in kiwi orchard than in arable land, with 42.63% of the kiwi orchard containing sufficient Olsen-P but 96.43% of the arable land being P deficient. In kiwi orchard soils, the change-point of phosphorus leaching was 40.11 mg·kg-1for Olsen-P, and 62.79% of the orchard had potential phosphorus leaching. However, there was not obvious change-point for arable land, implying weak phosphorus leaching under decades of cultivation. The phosphorus leaching could be detected as deep as 40 cm under two kinds of land use. Some measures should be taken to improve crop yield and quality and to reduce environmental risks.