Built along the contour at 3m spacings. Crops are planted on either side of the ridge. Runoff from the unplanted area is caught in the furrow and goes down into the root zone.
Used in home gardens and on smallholder fields; when mechanised, used on a large commercial scale. The system has been fine-tuned to South African conditions, and is called “in-field rainwater harvesting” (IRWH) in local publications.