长期施肥磷素盈亏及其对土壤磷素状况的影响

利用12年长期定位试验研究了长期施肥不同处理土娄土磷素去向和盈亏(平衡)及其对耕层土壤全磷、Olsen P的影响,结果表明,作物吸磷量随施磷量的增加而有所增加,作物对磷的利用有奢侈吸收现象;土壤耕层全磷、Olsen P及其增加量与土壤磷素盈亏呈极显著直线正相关;随肥料施入土壤的磷主要累积在土壤耕层(0~20 cm),施肥过高,特别是化肥配合有机肥施用会引起磷向土壤剖面下层淋移,M1NPK、M2NPK、SNPK、NPK和PK处理分别有34.7、33.0、2.2、8.8和6.4%的磷在100 cm土体内去向不明,有可能被淋洗到更深的土体中。长期不平衡或大量施磷,磷累积表观利用率低于15%,而平衡施肥,可以达到40%以上。

Phosphorus Balances and Its Effects on Soil Phosphorus Status under a 12-year Long-term Fertilization

This study investigated soil phosphorus balance,soil total phosphorus and available phosphorus at plough layers(0~20 cm) following a long-term fertilizer experiment of 12 years.The results showed that amounts of phosphorus uptake by crop increased with the increase of phosphorus application,a luxury uptake of P by crop was observed.Total P,Olsen-P and their increment caused by P applying were significantly and positively linear correlated with soil P balances.The applied fertilizer P was mostly retained in the plough layer.However,in the treatments of over-fertilized with phosphorus(Chemical fertilizer P combined with manure) led to P moving to the deeper soil layers.The unaccounted P within 100 cm depth was 34.7,33.0,2.2,8.8 and 6.4 % for the treatments of M2NPK,M1NPK,SNPK,NPK and PK,which probably leached down to the deeper soil layers.Apparent P use efficiency was less than 15%,under over-fertilized or imbalance fertilized treatments whereas it was improved up to above 40% for balanced fertilization.