Accumulation of hardly biodegradable plastics such as polyethylene in the environment is a major concern for health and sustainability. Recently, it has been reported that amylase can have a great impact on biodegradation of low-density polyethylene (LDPE)-starch blends. Therefore, biodegradation of such blends can be enhanced in natural media enriched by amylase producing microorganisms. To examine the idea, biodegradation of PE-starch (25 wt%) specimens was investigated in an agricultural soil used to grow potatoes. The impact of soil treatment (after four months) was studied through their physical, molecular, and thermal properties. The biotreatment led to 59%, 88% and 94% reduction in mass, tensile strength, and elongation respectively relative to the control specimens. Fourier-transform infrared spectroscopy (FT-IR) analysis indicated fundamental changes of the peak intensity of the main functional groups as well as a 27% increase in the carbonyl index of treated specimens. Moreover, the results of the gel permeation chromatography (GPC) pointed to a significant change of about 56% in molecular weight (Mz+1) and a 27% reduction in intrinsic viscosity of LDPE. These observations were supported by the results from thermal gravimetric analysis (TGA) and Differential scanning calorimetry (DSC). Finally, the results indicated that the agricultural soil rich in the amylase producing microorganisms provides proper conditions for the biodegradation of the PE-starch blend in a short time span.