An Evaluation of the Suitability of Soils for Mole Drainage in the South African Sugar Industry

In the South African sugar industry it is important that relatively inexpensive but viable drainage systems are de,:el,oped for those soils which have a low hydraulic conductrvity. From the results offield and laboratory investigations conducted during the past five years it appears that the use of unlined mole channels as an alternative for, or a supplement to conventional subsurface drainage, could be considered. Mole drainage is more successful in the heavy Rensburg and Willowbrook soil forms than in the variable duplex soils such as those of the Kroonstad and Longlands forms. The factors of slope, antecedent and current soil moisture content, soil bulk density, and soil type are important in determining the success of the installation and performance of a mole drainage system. Various guidelines are outlined for the use of mole drainage in the sugar industry.