长期定位施肥条件下紫色土无机磷形态演变研究

Inorganic phosphorus in a regosol(purple)soil under long-term phosphorus fertilization

应用蒋柏藩-顾益初无机磷分级体系对22年长期定位施肥试验紫色土0~100cm土层无机磷形态进行分级测定,研究了各形态的无机磷在土壤剖面的分布及演变规律。结果表明,长期施用化学磷肥以及有机无机肥配施处理的土壤全磷、有效磷和各形态无机磷均较试验前有不同程度的增加,且以猪粪＋NPK（M＋NPK）处理土壤增加最多,其中有效磷含量增加了6倍;不施肥（CK）和单施氮肥（N）的处理土壤有效磷、全磷和各形态无机磷出现了下降,其中有效磷含量分别降低了51.1%和53.5%。除了Fe-P和Ca_（10）-P含量下层高于上层外其余各形态无机磷都表现为耕层高于下层的特征。各处理Ca_2-P、Al-P、Ca_8-P、O-P等无机磷的剖面分布较为相似,均呈20~60cm下降比较迅速,80~100cm变化不大或者稍微上升的趋势,而Fe-P则表现为下层含量高于耕层。相关分析表明各组分无机磷对紫色土有效磷的贡献为Ca_2-P（0.9569）〉Al-P（0.9265）〉Ca_8-P（0.9100）〉Fe-P（0.8277）〉Ca_（10）-P（0.7449）〉O-P（0.7362）。长期有机无机肥配施可以显著增加磷素在土壤中的累积,并能减少土壤对磷素的固定,增强其在土壤中的移动,促进土壤磷素向有效态转化。

The Jiang Bofan-Gu Yichu Inorganic Phosphorus Grading System was used to grade measurements of different inorganic phosphorus forms in the 0-100 cm soil layer under a long term（22years）fertilizer application trial.Total phosphorus,available phosphorus and inorganic phosphorus all increased in soils receiving long-term application of chemical phosphate fertilizer and treatments combining organic and chemical fertilizer[pig manure＋NPK（M＋NPK）].Available phosphorus increased by a factor of six while available phosphorus,total phosphorus,and various forms of inorganic phosphorus reduced in soil without fertilizer.In addition the Fe-P and Ca_（10）-P content in the lower soil layers were higher than those in the upper layers;the same trend was apparent in all inorganic phosphorus forms.The distribution profiles for inorganic phosphorus including Ca_2-P,Al-P,Ca_8-P,and O-P were similar,all reduced rapidly between 20-60 cm soil depth but few changes were observed at 80-100 cm depth.The relative contribution of various forms of inorganic phosphorus to soil phosphorus was Ca_2-P（0.9569）〉Al-P（0.9265）〉Ca_8-P（0.9100）Fe-P（0.8277）〉Ca10-P（0.7449）O-P〉（0.7362）.Long-term application of organic and inorganic fertilizers to regosol soil could significantly increase the accumulation of phosphorus,suppress phosphorus fixation,enhance phosphorus mobility and improve phosphorus use efficiency.