抄録
Field operarion is related closely with field drainage and soil physical conditions. Criteria for the field operation have been described on basis of soil physical characteristics of fields. However, field condition is extremely heterogeneous and data obtained from the field shows great variebility. In this paper, problems were poited out for processing the soil physical data obtained from fields in order to estimate field condtions. And also, especially with relation to the field drainage, it was examined on basis of a simulation, dimension of samples required to get a representative value of hydraulic conductivity of a field with shrinkage cracks. As a result, it is made clear that a sample which has a diameter two or three times larger than intervals of the cracks would offer the representative value of the hydraulic conductivity of the field.
