Changes of Soil Fertility in Farming Area of Three Gorges Reservoir with Different Land Uses and Altitudes.

The Three Gorges Reservoir (TGR) area is an ecologically fragile area with the contradictions between human and land resources. Changes of soil fertility with different land uses (citrus, vegetables, cereals, agroforest) and altitudes (600-700 m and 700-900 m) in the TGR area were analyzed from 2005 to 2014, based on collecting soils samples from 60 sites annually. Concentrations of soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) in most of soil samples in study area decreased with time, but plant available nutrients increased. Concentrations of SOM and TN in middle and high elevation area were relatively high, while TP and TK in low elevation areas were relatively high. Converting hilly land to terraced fields improved soil fertility and increased soil N and P. The SOM and TN contents decreased significantly (p<0.05) in the fields for cereal crops, citrus and agroforest. The efficient approach in soil and water reservation will be a major concern for a sustainable development of agriculture in the TGR.