江西低丘红壤性水稻土的主要化学特性研究

三个红壤性水稻土的有机质和腐殖质的含量由淹育型水稻土→潴育型水稻土→潜育型水稻土依次逐渐增加,其C/N和H/P比值也顺次增大。它们的粘土矿物组成无明显差异。铁、锰物质在潴育型水稻土剖面中分异最明显,其次为淹育型水稻土;而无定形氧化铁在剖面中变幅最大却是潜育型水稻土;结晶态铁在土壤剖面中分异亦有一定规律,其中潴育型水稻土的指示性土层(W层)的晶胶率(结晶铁/无定形铁)远较其它土层为高,这种变化特性的差异,对区分不同水分作用的水稻土发育类型有一定的特殊意义;土壤络合态铁与土壤有机质含量有关。土壤氧化锰与土壤氧化铁相比虽然含量低,但对土壤氧化还原条件反应更加敏感,所以在土壤剖面中淋移趋势更加明显。

STUDIES ON THE PRINCIPAL CHEMICAL PROPERTIES OF PADDY SOIL FROM RED EARTH

The contents of organic matter and humus increase in order of the profile₁-profile₂-profile, of the three paddy soils derived from red earth. The carbon/nitrogen and humic acid/fulvic acid ratios increase in the same order. The composition of clay minerals of three paddy soils shows no obvious difference and is similar to their parent soil-red earth. These paddy soils are rich in iron and manganese oxides, especially in the illuvial horizon. Because of intense redoxing and eluviation-illuviation processes in soil, the distinct segregation of iron and manganese occurs in profile, and there is the most distinct segregation in profile, and the segregation of amorphous iron is most evident in the profiles, the iron in form of crystal segregates regularly also in the three profiles;the ratio of crystalline iron/amorphous iron in the dignostic horizon (w) of profile₂ is much higher than that in other horizons, this is rather important for distinction of the genetic types of paddy soil developed under different water regimes. The content of the iron in form of complex compound is related to that of the organic matter. As compared with iron oxide, manganese is more sensitive to the change of redoxing conditions, the segregation of manganese in soil profile tends to be more distinct than that of iron, although the content of manganese in soil is rather low.