我国中亚热带缓丘区红粘土红壤肥力的演化Ⅱ.化学和生物学肥力的演化

本文着重探讨红粘土红壤化学和生物学肥力在利用过程中的演化特征，并通过聚类分析筛选出评价红壤化学和化学肥力演化的指标，并进行了相应的评价。结果表明：红粘土红壤的要草地及荒地系统由于长期受侵淋溶等退化过程的影响，土壤养分水平已跌至“保底”值．垦殖利用后，其化学肥力随着耕垦熟化过程不断提高，表现为土壤中各种速效养分及交换性Ｃａ、Ｍｇ含量均增加，而交换性Ａ１含量降低。同样，林草地系统红粘土红壤的生长学肥力

FERTILITY EVOLUTION OF RED SOIL DERIVED FROM QUATERNARY RED CLAY IN LOW-HILLY REGION IN MIDDLE SUBTROPICS II. EVOLUTION OF SOIL CHEMICAL AND BIOLOGICAL FERTILITIES

This is the second paper to study the fertility evolution of red soil derived from Quaternary red clay in low-hilly region in the middle subtropics from point of systematic view.The characteristics of soil chemical and biological fertility evolutions under various land use patterns were researched,then the evaluation indexes were selected with cluster analysis and their weight coefficients determined with factor analysis.Results showed that the chemical properties had dropped to the "Valley-bottom value" in forest and waste land systems without input.Soil chemical fertility in cultivated-land and garden systems increased with land reclamation and soil maturation process,the content of soil nutrient and exchangeable Ca and Mg raised,but exchangeable A1 dropped.The evolution of soil biological fertility was similar to that of soil chemical fertility.Similarly,the soil biological fertility in cultivated-land and garden systems increased with land reclamation and soil maturation process,it was shown by the raise of soil organic matter content,the improvement of humus quality,and the increase of microbe and activity of soil enzyme.The composition of exchangeable canon and the soil nutrient content can be used as the indexes to evaluate soil chemical fertility evolution,especially the former is more important.The changes of soil organic matter,humic acid,total amount of microbe,microbial biomass C,activity of urease and phosphatase reflected mainly the evolution of soil biological fertility.