Chemical and Physical Characteristics of Red Soils from Zhejiang Province, Southern China

Abstract

Red soils, consisting of Ultisols and partly of Alfisols under the Soil Taxonomy system of the USA, are important land resources in China. A good understanding of the physical and chemical properties of these soils is essential for their improved management and utilization. In this study, typical profile samples of red soils were collected from Zhejiang Province, and their physical and chemical properties, nutrient concentrations and water-stable aggregate distributions were studied. The red soils had low cation exchange capacity, high exchangeable acidity, and low pH. The textures of the red soils vary greatly, from clayey to sandy loam, and are mainly influenced by parent material. Amounts of organic matter, total nitrogen (N), total phosphorus (P) and total potassium (K) varied with parent materials, elevations and land use patterns. About 60% of the red soils had total N < 1.5 g kg−1,and Olsen-P < 5 g kg−1, and 32% of the soils were deficient in available K (< 80 g kg−1). Deficiencies of available B, Mo and Zn were common, whereas available Fe, Mn and Cu were abundant in the red soils. Organic matter plays a key role in the formation of water-stable soil aggregates. The larger the soil aggregate size, the greater the impact of organic matter on the water stability of the aggregates. Small water-stable aggregates (0.50–0.25 mm) in the red soils were chiefly cemented by Fe and Al oxides. Land use patterns and parent materials had a significant influence on the formation and water-stability of aggregates in the red soils.