石灰性土壤无机磷的形态分布及其有效性

本文应用蒋柏藩和顾益初(1989)提出的石灰性土壤无机磷的分级方法,对我国北方主要的石灰性土类进行了无机磷形态分级的研究,并对其有效性作出了初步评价。供试的甘肃、陕西和河南的16种土壤的无机磷形态的分布情况为:Ca₂-P平均占无机磷总量的1.34%,Ca-P占9.91%,Al-P占4.27%,Fe-P占4.40%,O-P占10.9%,Ca₁₀-P占69.1%。生物试验的结果表明:Ca₂-P型的磷酸盐是最有效的,也是作物磷素营养的主要来源;Ca₈-P、Al-P和Fe-P可以作为缓效磷源;Ca₁₀-P和O-P只是一种潜在磷源。本研究为石灰性土壤无机磷的研究和磷肥的合理施用提供了理论依据。

DISTRIBUTION AND AVAILABILITY OF VARIOUS FORMS OF INORGANIC-P IN CALCAREOUS SOILS

This paper deals with sixteen typical calcareous soils (pH 8.09-8.69 and CaCO₃, content 2.95-15.8%), i.e. sierozem, chestnut soil, dark loessial soil, yellow cultivated loessial aoil, old manaial loessial soil, black loessial soil, and yellow fluvoaquic soil sampled, respectively, from Gansu, Shanxi, and Henan provinces of China. The scheme developed by Jiang Baifan and Gu Yichu was employed for inorganic-P fractionation and the results show that the total amount of inorganic-P in the calcaerous soils tested is 550 ppm on average, in which Ca₂-P, Ca₈-P, Al-P, Fo-P, O-P, and Ca₁₀-P account for 1.34%, 9.91%, 4.27%, 4.40%, 10.9% and 69.1% respectively. The regression analyses between different forms of inorganic-P and P uptaken by plants indicate that the availability of Ca₂-P is surely recognized, and the P uptaken by plants is mainly Ca₂-P; Ca₈-P, Al-P, and Fe-P are also available forms of inorganic-P; while Ca₁₀-P is unavailable.