The effect of mole drainage on soil moisture and on the movement of water in surface run off from Tokomaru silt loam under pasture was investigated using two 80 m2surface runoff plots each of 6#xB0; slope. Frequently, particularly during autumn and early winter, surface runoff was reduced on the drained site by between 25 and 50 of that on the undrained site. However, mole drainage was less effective in reducing surface runoff during prolonged rainfall, as in wet winter periods. Under such conditions, there was a reduction both in the differences between infiltration rates and in the infiltration rates themselves for the drained and undrained sites. Regression and correlation analyses suggested that soil moisture was a primary factor influencing surface runoff from the undrained site. In contrast, rainfall intensity and duration were the primary factors influencing surface runoff from the drained site. Greater amounts of sediment were transported in surface runoff from the undrained plot and up to 95 of this sediment was 63 #xB5;m in diameter. Mole drainage had a pronounced effect in reducing the quantity of sediment transported.
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