Abstract
In a large sized paddy field, many farmers adopt the direct sowing method of rice because of low cost. This method demands the highly leveled farmland in precision. However, as a size of field lot increases, load of leveling works strongly increases. Therefore, improved land leveling techniques with high precision are needed in the consolidation of large size paddy field. The authors examined the relation between the shapes of field lot and the load of leveling works. As a result, the following conclusions have been introduced.
In condition with the same paddy field area, load of land leveling works increases strongly as the difference between the long and short side of rectangular lot becomes larger. In order to decrease the load of land leveling, in preliminary works of consolidation, we need to adjust and construct the land level to be the designed value as far as possible, and the tolerance of preliminary works becomes narrow as the lot size increases, and/or the difference of long and short sides of rectangular plot increases. Therefore, the role of management in leveling works is very important in case of the land leveling of longer shape rectangular paddy field with large size.
