| Soil is a fundamental element of ecosystem and the material basis of human life. Studying on spatio-temporal variability of soil properties is of great significance for improvement of soil fertility and sustainable development of the agricultural resource.With geo-statistics and GIS technique, this paper analyzed the spatio-temporal variability of soil properties in two stages (1981and2011) in Shuyang County, Jiangsu Province, and discussed the main factors affecting the spatio-temporal variability. The main results were as follows:(1) The results of descriptive statistics showed the co-efficient of Variability (CV) of soil pH, organic matter (SOM), total nitrogen (TN), total phosphorus (TP), available P (AP) and available potassium (AK) were13.68%,34.04%,31.62%,30.73%,66.92%and37.23%, respectively, belonging to moderate variability. The CV of soil AP was the most with66.92%, which indicated that AP was easily affected by human activities such as fertilization.(2) The analysis showed that spatial variability of different soil properties varied from one to each other in two stages (1981and2011). pH had a higher value in southeast than in northwest in both two stages; the content of SOM in northeast and northwest were higher in both two stages. In1981, there was a lowest content of SOM in west, while in2011, it was in south; Total nitrogen had a similar spatial variability with SOM; Total P had a higher content in southeast than in northwest in two stages; In1981, no significant difference was showed in spatial distribution of AP in spatial and the high-value region of AP was scattered rather than concentrated in2011; There was a different spatial distribution of AK in two stages. The soil AK level was high in east and low in west in1981and high in northeast and low in south in2011. (3) In temporal, the soil pH had a decreased tendency of a0.61-unit in average, and the SOM, TN, TP, AP and AK had generally an increased tendency in the past30years (1981-2011). From the view of soil types, Old loess and Brown Loess had the biggest decreases in soil pH; Brown soil had a biggest increase in the content of SOM, TN, TP, AP and AK; Lake black soil, Mixed soil and Silty soil had a negative increases in the content of AK.(4) The study showed that soil texture and soil types had great influences over the spatial distribution of pH and soil nutrient in1981. As the time went by, by2011, farming management, especially fertilization and land use patterns had become the main factors affecting the spatial distribution of pH and soil nutrient. The driving factors affecting the temporal variability of pH and soil nutrient were human activities, including the increase of fertilizer recommendation, the changes of NPK ratios of fertilization, the transformation of land-use patterns and the extension of crop-residue incorporation. |
