南亚热带丘陵湿润铁铝土结构退化及其机理

STUDIES ON STRUCTURE DEGRADATION AND ITS POSSIBLE MECHANISM OF UDIC FERRALISOLS IN SOUTHERN SUBTROPICAL HILLS

本文探讨了南亚热带丘陵湿润铁铝土结构退化过程特征及其机理。结果表明，与地带性自然植被下丘陵湿润铁铝土比较，次生植被或人工植被下丘陵湿润铁铝土结构退化现象明显。表现在表土砂化，即砂粒含量相对增加，粘粒含量相对减少；土壤结构稳定性下降，主要体现在较大粒径水稳性团聚体减少；土壤孔隙性变差，主要体现在容重增加和较大孔径的孔隙减少。对自然湿润铁铝土而言，容重增加、较大孔隙减少更为明显；对耕型湿润铁铝土而言，土壤结构稳定性下降，表土砂化更为突出。数理统计分析结果表明，养分贫瘠化，特别是有机质减少，是丘陵湿润铁铝土结构退化的主要内在因素。

This paper deals with the soil structure degradation characteristics and its possible mechanism in Udic ferralisols. Results showed that compared with the soil under zonal natural vegetation it suffered more structure degradation under secondary or man-made vegetation. It was found that the stature degradation in Udic ferralisols was characterized by sandification of surface soil, lowering of aggregates stability, decrease in bigger aggregates, deterioration of soil porosity, increase of bulk density and lowering of bigger pore content. For natural Udic ferralisols, the increase of bulk density and decrease in bigger pore aggregate content were more obvious, however, for cultivated lands, the lowering of aggregates stability and sandification of surface soil were more serious. Mathematical analytic results indicated that the nutrients improvement, especially the organic matter deficient, might be the main interior factor causing structure degradation of Udic ferralisols.