DISTRIBUTIONS OF PHOSPHORUS IN EUM-ORTHIC ANTHROSOLS AND ITS PEDOGENIC IMPLICATION
土垫旱耕人为土中磷的分布特征及其土壤发生学意义

Phosphorus(P),an important soil nutrient element,has its change closely related to natural pedogenic processes and human activities.In order to understand P behaviors during natural and anthropogenic pedogensis,three profiles with different land uses and different thickness of cumulic layers were analyzed.The results show that compared with the underlying layer of naturally formed Luvisols,total P(TP),available P(AP),organic P(OP),and inorganic P(IP)contents in the upper layer of Eum-Orthic Anthrosols increased 0.29,4.67,0.20,0.30 times respectively.In the upper layer of Eum-Orthic Anthrosols,all phosphorus forms had the highest contents in Aup1 horizon and decreased rapidly down to Aup2 horizon.TP and OP decreased gradually from Aup2 horizon to Aupb horizon and then to 2A horizon,reflecting that the intensity of human activity was different in different historical periods.In the underlying layer of naturally formed Luvisols,because P was inherited from loess and mainly affected by natural factors,the contents of TP,AP,OP,IP were lower than in the horizons of Eum-Orthic Anthrosols.P contents in horizons of Eum-Orthic Anthrosols at the toe-slope position with vegetable land use were higher than those at the upper terrace crop land.The distribution patterns of different forms of P in profiles were attributed to their mobility,the calcium content,as well as uptake by roots,irrigation,and fertilization.The relationship between OP and OP/IP and the relationship between different forms of P and soil organic matter,iron,calcium,and clay content reflected the different effects of natural soil genesis processes and human activities.