Abstract
In the paddy field where the chemical properties of the soil were affected by the continuous application of swine urine, the physical properties, especially the bearing capacity and soil structure, were examined as indications of farm machinery trafficability. The bearing capacity of the soil supplied with swine urine continuously was much lower than that of the soil supplied with chemical fertilizers and it was impossible to drive a tractor in the former field 35 days after surface drainage. The capillary pore content in lower suction range, plasticity index and sedimentation volume of the topsoil increased with continuous application of swine urine. In the ill-drained paddy field, it is considered that continuous application of swine urine worsens its wet feature, lowers its bearing capacity, leads to formation of weak soil structure, and lowers the farm machinery trafficability.
