YAMASHITA, T., 1984, Improvement of weak foundation of paddy fields by subsurface drainage system,
Tech bull., Trop. Agr. Res. Center, Japan No. 18
Underground drainage in paddy fields may contribute to the consolidation of the soil bearing capacity of the fields at the time of harvest in order to facilitate farm operations.
The present field study was carried out in test plots located in the Muda Irrigation Project Area, Malaysia.
The soil conditions peculiar to the area are known to contribute to the formation of a weak foundation in the rainy season. When large machines operate during the off-season harvesting period, the weak soil conditions make farm operations difficult. Under such circumstances, it is necessary to increase the soil bearing capacity by improving the drainage. From the results obtained during the investigation, it was demonstrated that the soil bearing capacity increased year after year, especially in the plots with complete underground drainage. However, the soil bearing capacity increased only slightly during the interval between the onset of drainage and the harvesting period. Since the drainage of the surface water was difficult to perform during such a short period, the soil was insufficiently dried. Supplementary underground drainage is necessary to drain fast and uniformly the surface water of the fields and the excess water in the soil zone.