Abstract: Vicia villosa is commonly used as a green manure or pasture in north China. In order to provide a scientific basis for its use as green manure in south China, a study has been undertaken in winter-fallowed red soil uplands used for sweet potato crops in Dongxiang County, Jiangxi Province. The decomposition and nutrient release characteristics of Turkmen V. villosa were tested with different application amounts. Nylon net bags (30 cm×20 cm) were used to assess three application treatments: low (90 g fresh grass per bag, equivalent to 15000 kg/ha), medium (135 g fresh grass per bag, equivalent to 22500 kg/ha) and high (180 g fresh grass per bag, equivalent to 30000 kg/ha). The rates of dry matter decomposition and nutrient release were monitored at 10, 20, 30, 60, 90, 120, 150 and 180 days after application. The results showed that all three treatments decomposed rapidly over the first 20 days and then the release speeds slowed. The dry matter decomposition rate reached 60.59%-66.72% after 20 days and 70.19%-84.18% by the end of the experiment. Carbon (C), nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulphur (S), copper (Cu) and zinc (Zn) released rapidly in the first 20 days, reaching 62.1%-68.1%, 71.5%-76.0%, 70.4%-81.8%, 97.3%-97.7%, 75.6%-82.1%, 73.4%-79.0%, 78.6%-81.6% and 84.1%-88.4% respectively. Calcium (Ca) and manganese (Mn) released relatively slowly at first (43.5%-63.8% and 20.6%-35.9% after 20 days), but their release rates reached 86.0%-92.6% and 54.2%-76.7% respectively by the end of the experiment. Iron (Fe) was a significant “enrichment” phenomenon in the early stages but its release rate was ultimately very low. The general rules of decomposition and nutrient release did not change significantly with increasing application amounts. The release rates and speeds of C, N, P and K in the different applications fitted well with both the power function formula y=ax^b (all P<0.001) and the exponential decay model v=v₀e^-kx (all P<0.01). Regression analysis showed that the delay effects of nutrient release caused by increasing application amounts were C and N>P>K, with the full release of these nutrients needing 354-406 d, 791-1358 d, 87-122 d and 16-27 d respectively. The release speeds of C, N, P and K improved significantly over the first 10 and 20 d after application, following which the values remained at extremely low levels. This pattern did not change significantly with higher applications. Therefore, the ability to continuously supply nutrients for following crops by increasing the application amounts of V. villosa is very limited. Optimum application amounts need to be determined by fully considering the fertilizer requirements of the following crops.