长期施肥对砂姜黑土无机磷形态的影响

采用顾益初、蒋柏藩的无机磷分级方法，研究了长期施肥下砂姜黑土无机磷组分含量变化、生物有效性及其与土壤有效磷的关系。结果表明，长期耗竭状况下Ca2-P和Ca8-P的植物营养效率最高，其次为Al-P和Fe-P，O-P和Ca10-P也表现出了一定的有效性；Fe-P和Al-P对植物的营养贡献率最高，虽然Ca2-P和Ca8-P活性最高，但由于含量低，对磷素养分的贡献率较低，土壤磷素极度耗竭下，Ca2-P的植物营养贡献率甚至低于Ca10-P和O-P。砂姜黑土对磷的固定严重，土壤中积累的磷主要向Al-P、Fe-P和有效性更低的Ca10-P和O-P转化，Ca2-P、Ca8-P的增量较少。相关分析和通径分析表明，无机磷组分对有效磷的贡献为:Al-P＞Ca8-P＞Ca2-P＞Fe-P＞O-P＞Ca10-P；建立了Olsen-P与无机磷组分间的回归方程:Y = 3.8751 +0.4674X1 +0.4470X2+ 0.3769X3-0.1166X4-0.07838 X 5 (Y代表有效磷含量，X1、、X2、X3 、X4 、X5分别代表Ca2-P、Ca8-P、Al-P、Fe-P和Ca10-P含量；P＜0.01，R2=0.9989)。

Effects of long-term fertilization on inorganic phosphorus fractions in lime concretion black soil

The effects of long-term fertilization on inorganic phosphorus fractions and their availability in Shajiang black soil were studied using the fraction classification developed by Gu Yi-chu and Jiang Bo-fan. The results show that nutrition efficiency of Ca2-P and Ca8-P is higher than that of Al-P and Fe-P respectively, and Ca10-P and O-P have some availability when soil phosphorus is depleted. The contribution rates of Al-P and Fe-P for plant are the highest, while those of Ca2-P and Ca8-P are low although the two fractions have high availability. To some extent, the contribution rate of Ca2-P is even lower than that of Ca10-P and O-P when soil phosphorus is extremely depleted. The accumulated phosphorus is mainly transformed into the fractions of Al-P, Fe-P, O-P and Ca10-P, while the transformation to Ca2-P and Ca8-P are little. The results of correlation and path analyses indicate that soil available P is significantly correlated to Ca2-P, Ca8-P, Fe-P, Al-P, O-P and Ca10-P. The contribution of the different inorganic phosphorus fractions to soil available P is Al-P＞Ca8-P＞Ca2-P＞Fe-P＞O-P＞Ca10-P.