土垫旱耕人为土中磷的分布特征及其土壤发生学意义

本研究以我国半干旱地区的土垫旱耕人为土为对象,分析在自然土壤发生过程和人类活动影响下,不同形成阶段内土壤中总磷（TP）、速效磷（AP）、有机磷（OP）和无机磷（IP）的含量和分布特征。同时也探讨现代土壤利用方式的影响。结果表明,与半干润淋溶土层相比,堆垫层总磷、速效磷、有机磷和无机磷平均分别增加0.29,4.67,0.20和0.30倍;堆垫层段内,现代耕作层（Aup1）中各形态磷含量最高,向下至亚耕层（Aup2）迅速降低,而由亚耕层（Aup2）至埋藏耕作层（Aupb）和半干润淋溶土表层（2A）总磷和无机磷逐渐降低,反映了不同历史时期人类活动强度不同;半干润淋溶土层段内,土壤中的磷主要来自于黄土母质,其变化以受自然成土因素影响为主,总磷、速效磷、有机磷、无机磷含量较低且层间变化不大。菜地土壤中堆垫层内各形态磷的含量显著大于农田土壤。土壤利用方式对磷的影响大于堆垫厚度。各形态磷在剖面中的分布模式与磷素自身的迁移、淋失到下层的钙等因素有关,同时也受根系的吸收、人为灌溉施肥等因素影响。剖面中OP与OP/IP之间以及各形态磷与其他土壤理化性质的关系可以指示自然条件和人为影响的差异。

DISTRIBUTIONS OF PHOSPHORUS IN EUM-ORTHIC ANTHROSOLS AND ITS PEDOGENIC IMPLICATION

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.