耕作白浆土有机无机复合体腐殖质组成及类型

COMPOSITION AND TYPES OF HUMUS IN DIFFERENT PARTICLE FRACTIONS OF ARABLE ALBIC SOIL

本文用Kumada法研究了耕作白浆土各粒径级分中有机质的特征。结果表明，土壤及各粒径级分中有机碳含量多是高肥土壤大于低肥，并随复合体粒径增大而下降，下降的比例是高肥小于低肥；土壤有机质及粘粒含量影响有机碳贮量曲线与各粒径级分含量曲线的关系，高肥土壤中粉粒或细砂级分中的有机碳贮量明显高于低肥。土壤及各粒径级分的腐殖质以能被0.1mol／LNaOH提取的游离态为主，其胡敏酸（HA）含量、PQ1值等多项指标均有高肥大于低肥的趋势，由logk与RF值所决定的HA腐殖化度则是高肥小于低肥。上述规律在粉粒及细砂级分中表现的最为明显。随粒径增大，游离态腐殖质及其HA含量等均有下降趋势，但PQ1则是粉粒中稍高；游离态HA类型随粒径增大而变化的序列为：A型（粘粒）-B型（粉粒）-Rp型（细砂）。0.1mol／LNa4P2O7提取的结合态腐殖质及其HA含量与腐殖化度等均以粉粒中最高，粘粒及细砂中次之，PQ2则随粒径的增大而减小；无论肥力高低，结合态HA大都为腐殖化度较高的A型，少数为B及P型。

In this work, the characteristics of organic matter in different particle fractions of albic soil were studied by using Kumada's method. The results showed that the connet of organic C in fertile soils and their particle fractions was higher than that in poor soll and it deCeased with the increase of particle diameter. The decrement was smaler in fertile soil than that in poor soil. Soil organic matter and clay content affected the consistency between the storage curve of organic C and the content curve of particle fractions. Organic C storage of clay or fine sand particles in fertile soil was sighficantly higher than that in poor soil. The humus in soils and their particle fractions were mainly free form which can be extracted by 0.1 mol/L NaOH.Some indexes such as htalc acd content and the PQ value of free form were higher in fertile soil than those in poor soil. But the degree of htalfication based on logK and RF values was lower in fertile soil.than that in poor soil. Those trends were much clear for silt and fine sand particles. With the increase of particle diameter,the contents of free humus and its humic acid tended to decline, but the PQ1 value was higher in silt particle thtrn that in other particle fractions. The type of free humic acid changed with the increase of particle diameter in the order of A type (clay)→B type (silt)→Rp (fine sand). The content of combined humus which was extracted by 0.1 mol/L Na4P2O7 and its hac acid content and the degree the hynufication were the highest in the silt particle, but PQ, decreased with the increase of particle diameter. Both in fertile soil and in poor soil, combined humic acid mainly belonged to A type in which the degree of humification was higher, only a few belonged to B type or P type.