Physico-chemical characteristics of the soils from the coastal plain in Shanghai, China

Characterization of the physico-chemical properties of the soils collected from the coastal plain covering a total area of about 1,908 km(2) in the Changjiang Delta in Shanghai, China, has been conducted in order to investigate the current status of agricultural soils, with special reference to the effect of alluvial deposits on the development and utilization of the soils. The experimental results indicated that the soils of the coastal plain displayed a sandy (loam) texture. The soils from Qingcun and Guangming Towns in the Fengxian District, Shanghai, contained the highest amount of clay, showing the highest capacity to remain fertile. The soils from Xinghuo Town in the Fengxian District contained the highest amount of salts due to the strong mineralization degree from the groundwater and the effect of the marine deposits from the Hangzhou Bay, which resulted in the highest exchangeable sodium percentage in the soils. The soils from greenhouses (Sunqiao, Huinan, and Qingcun Towns) showed a higher salt content than others, in contrast to the paddy and orchard soils. The analysis of the soil fertility indicated that the soils from Guangming and Qingcun Towns in Fengxian were rich in organic matter, total nitrogen, and total potassium, and were fertile soils. In contrast, though the soil from Xinghuo Town was rich in potassium, it lacked other nutrients. The phosphorus content in the soils was mainly determined by the application of fertilizers, and the total and available phosphorus contents in the greenhouse soils were higher than those in the soils with other land use types.