摘要
本文主要研究不同生物气候条件下由玄武岩母质发育的红壤、赤红壤和砖红壤的理化性质及矿物组成。粘粒中氧化铁的含量都很高,为16.98±0.83%。砖红壤与赤红壤粘粒中高岭石与非晶物质的含量相近,它们之间的差异是赤红壤中没有三水铝石,而含有7—11%蒙皂石。红壤粘粒中高岭石和非晶物质的含量都低于砖红壤和赤红壤,而水云母和蒙皂石的含量较高,也没有三水铝石。粘粒含量、阳离子交换量、硅铝率、硅铁铝率、铁的游离度和风化淋溶系数等都反映了土壤风化程度上的差异,它与水热条件特别是年均温和积温有关,进一步说明生物气候因素引起的土壤性质及矿物组成变化比其它因素强烈。砖红壤与砖红壤性水稻土的差异是在氧化铁形态上;红壤与红壤性水稻土相比,后者粘粒中蒙皂石含量略高,水云母含量略低。
This paper deals mainly with the physico-chemical properties and mineral compositions of red earths,lateritic red earths and latosols developed from basalts under different conditions of biological climate.The content of iron oxide in clays from all soils was higher,being 16.98±0.83%.The iron oxides in clay fraction were dominated by hematites and geothites,but those in coarse fraction by magnetites,hematites and anatases.The free degrees(free FeO/total FeO)of iron oxides of red earths,lateritic red earths and latosols were 53.3±2.2%,71.1±2.8%,and 82.8±3.1%respectively,and sihca-alumaina ration 3.29±0.05,2.33±0.05,and 1.89±0.03 respectively.The degree of allitic enrichment strengthened with increase of temperature and rainfall.The weathering leached coefficient ba(ha=KO+NaO+CaO+MgO molecular ration)was used to indicate the weathering intensity of soils.The ba valus of red earths,lateritic red earths and latosols were 0.22±0.01,0.13±0.002,and 0.05±0.01 respectively.The contents of kaolinites and non-crystalline materials in clays of latosol and lateritic red earth were approximate.H0wever,laterric red earth contained 7—11%smectites without gibbsite.In clay of red earth the contents of kaolinites and non-crystalline materials were lower than those in lateritic red earth and latosol,but the content of hydromica and smectite was higher,and these was also no gibbsite.The composition of clay minerals of the three soils varied greatly.The contents of kaolinites,non-crystalline materials and iron oxides increased gradually and crystal form of kaolinites chenged better from north to south.The contents of smectires and hydromicas decreased gradually from north to south.The gibbsite was only found in latosols where gibbsites were formed from kaolinites through desilicification under an eluviation condition.This showed that the weathering indensity of the soils was rather strong.In the 2—10μm fraction,there were many secondary clay minerals,in addition to some quartz and feldspars.All of the content of clay,CEC,SiO/AlO,SiO/RO,free degree of iron oxide and weathering eluviation coefficient of soils in the present study could reflecte the weathering degree which was related to soil hydrothermal conditions,specially mean annual temperature and accumulated temperature.It is shown that changes of soil properties and mineral composition induced by biologic and climatic factors were greater than those by others.In the composition of clay minerals,paddy soils were similar to their precursor soils or soil-forming parent materials from which they derived.However Latosols differed,from.paddy soils derived latosols in the form of iron oxides.X-ray diffraction results showed that the iron oxides in latosol mainly existed as hematites,but in the paddy soils derived from latosols the content of goethites increased obviously.Compared with the paddy soils derived red earths,the red earths contained a little less smectites,but more hydromicas.
作者
蒋梅茵
杨德湧
Jiang Meiyin;Yang Deyong(Institute of Soil Science,Academia Sinica,Namjing,210008)
出处
《土壤学报》
CAS
CSCD
北大核心
1991年第3期268-275,共8页
Acta Pedologica Sinica
基金
国家自然科学基金资助项目.
