长期施肥对石灰性潮土无机磷形态的影响

在河北省辛集市马兰农场的肥料长期定位试验点上 ,进行了石灰性土壤在无机磷耗竭和积累状况下 ,无机磷形态的转化及其在土壤剖面中的分步规律和施肥的影响。结果表明 ,在土壤磷处于耗竭的情况下 ,植物主要吸收利用了土壤的Ca8-P、Al-P、Fe-P和Ca2-P ,只有在极度缺磷的情况下 ,植物才利用土壤中的Ca10-P ,而O-P是土壤中极稳定的无机磷形态 ,植物一般不能利用。长期单施无机磷肥 ,土壤无机磷含量有所提高 ,积累的无机磷约 60%转化成Ca10-P和O-P。有机肥与化肥配合施用 ,积累的无机磷约有占积累无机磷的 2/3转化成Ca2-P和Ca8-P ,而且各形态无机磷的含量在土壤表层和下层均有所提高 ,一般随有机肥用量的增加 ,下层土壤无机磷的增加幅度也大 ,且影响的深度也较深。但在本试验条件下 ,施肥深度的影响不会超过50cm。

Effect of long-term fertilization on the forms of inorganic phosphorus in calcareous fluvo-aquic soil

A new soil inorganic phosphorus fractionation method proposed by Jiang Bofan Gu Yichu(1989) was adopted to study the effect of long term fertilization on transformation of inorganic phosphorus in surface soil, distribution of inorganic phosphorus in soil profile The result indicated that plant mainly used inorganic phosphorus in forms of Ca₈-P-Al P-Fe P and Ca₂-P in surface soil and subsoil within 30～50cm when soil phosphorus was depleted Only in excessive P depletion could plant use Ca₁₀-P O-P was the most stable form of inorganic phosphorus that plant could not use When soil phosphorus accumulated by application of phosphorus fertilizer, the accumulated phosphorus mainly transformed into the forms of Ca₁₀-P and O-P that plant can hardly use While combine use of chemical fertilizer and organic manure, the accumulated phosphorus mainly transformed into readily available forms of Ca₂-P and Ca₈-P Not only the inorganic phosphorus pool of Ca₈-P-Al P-Fe P and Ca₂-P were enlarged by combine use of chemical fertilizer and organic manure, but also the contents of these forms of inorganic phosphorus increased in the soil below surface, and as the application of organic manure increased, the deeper depth of soil profile was affected In our study condition, the effect of fertilization on the contents of inorganic phosphorus forms wouldn't exceed 50cm below the surface soil The contents of O-P and Ca₁₀-P in the subsoil were little affected by fertilization, their contents were mainly affected by soil texture O-P (and Fe-P also) generally accumulated in clay layer in the soil profile, on the contrary, Ca₁₀-P accumulated in sandy soil But the other two forms of Ca-P were not found accumulating in Sandy soil in the soil profile