Although underdrainage has been studied for a long time, it is the third attempt in korea to execute, using P. V. C.(plastic) suction pipes in the low and wet fields. First, three execution plots and three control plots were set, then the drainage method and volume, soil temperature, growth and yield of crops, and under ground water level in the execution plot have been examined. These experiments have conducted with No-ngnim No 6(rice), and Palgweng (rice) which are the recommended varieties. And the above experiments have been executed for seven months between January and July. 1970. The experimenntal method adopted and the results obtained through the exeperiments are as follows: Methods 1. Depth : 85m 2. Interval : 6.0m 3. One horizontal lock was set in the execution plot. 4. P.V.C. suction pipe filters were bound with glass nylon. Results 1. It tood about 4.5 hours to drain the soil moisture to adjust for barley cultivation. 2. The soil temperature : a) Went down between November, 69 and April. 70. b) Went Up between May, 70. and July, 70. 3. The death rates from cold were : 13% of wheat, and 24% of rice-barley. 4. Growth 1) Length of ears E plot NON-RIM, No-4 : 5.5cm DOWN : 4.5cm C plot NON-RIM, No-4 : 5.0cm DOWN : 4.1cm b) Number of ears E plot NON-RIM, No-4 : 76 DOWN : 78 C plot NONRIM, No-4 : 43 DOWN : 40 c) Stem height E plot NONRIM, No-4 : 110cm DOWN : 95cm C plot NONRIM, No-4 : 110cm DOWN : 80cm 5. Yield of crops. a) The weight of 1,000 ears. E plot NONRIM, No-4 : 37g DOWN : 36g C plot NONRIM, No-4 : 15g DOWN : 16