Tempo-Spatial Variation And Its Influencing Factors Of Selected Soil Properties Of The Farmland In A Typical Area Of The Yangtze River Delta Region

The soil properties in agricultural ecosystem are important indexes of estimating the soil fertility and soil quality. It is of important significance to study spatio-temporal variability of soil properties for controlling soil fertility directionally, improving eco-environment quality and promoting sustainable development of the society and agriculture. This paper studied the tempo-spatial variation of soil organic matter (SOM), soil total nitrogen (STN), exchangeable potassium (Ex-K), and availability of Cu, Fe, Mn, and Zn in soil in Rugao city, Jiangsu Province, an agricultural area in Yangtze River Delta region.In spatial, the soils of the loam Stagnic Anthrosols (Baipu) and clay Aquic Cambosols (Changqingsha) in eastern and southern part of the area had high SOM, STN, Ex-K and available metals contents, the soils of the sand Ustic Cambosols (Guoyuan), sand Aqutic Cambosols (Motou) in mid-western areas had low contents. In 1982, the soil had high pH in northern and mid-western part of the area and in had high pH in southern part of the area in 1997 and in 2002.In temporal, the soil pH had a continuously decreased tendency, and the SOM and STN had a continuously increased tendency in the past 20 years (1982-2002). However, the Ex-K had a decreased from 1982 to 1997 and had an increased tendency from 1997 to 2002. From 1982 to 1997, the soil pH had a significant decrease in the mid-western areas; and the soils in the mid-western areas had a rapidly increased SOM and STN but those in the eastern and southern areas a slowly increase. But the Ex-K had a rapidly decreased in the eastern and southern areas. From 1997 to 2002, the soils in the eastern and southern areas had a rapidly increased SOM and those in the mid-western areas a slow increase or decrease. However, STN had a slight increase in the former soils but no change and even decrease in the latter soils. At one time, only the soil of clay Aquic Cambosols (Changqingsha) in southern part of the area had a significant decrease in soil pH and the soil of available potassium had a rapidly increased in the eastern and southern areas.