Low density polyethylene (LDPE) was blended with thermoplastic starch (TPS) by twin screw compounder to prepare partially degradable mulch films. In the present study, ferric stearate and manganese(II) stearate were used as pro-oxidant and the effect of different pro-oxidants on the degradation of the blends were investigated. The blended mulch films were buried in soil inoculated with Coriolus versicolor (L.) Quél. for 180 days for the degradation. The chemical structures of the films were evaluated by FTIR spectroscopy and the weight loss of all samples was measured before and after soil burial treatment. The effects of two different pro-oxidants on thermal and tensile properties of blends were determined by TGA and mechanical analysis. A synergetic effect between ferric stearate and citric acid was observed. Using both in the blends resulted in higher thermal stability of TPS in the blends. Significant improvement of the mechanical properties was also observed. However, when manganese(II) stearate used together with citric acid a decrease in the mechanical properties was observed compared blends with stearic acid.