Measurement of 2400 clumps of root suckers of Brigalow (Acacia harpophylla F. vM.) showed that in over 90 per cent of clumps the depth from the soil surface to the centre of the parent root was less than 4 inches. Suckering was significantly shallower on non-gilgai than on gilgai soils. An experiment on gilgai soil compared the effectiveness of ploughing to depths of 4 inches and 8 inches for the elimination of suckers. After four ploughings in two pears both treatments gave an identical kill of 80 per cent. A final overall ploughing at 4 inches increased the kill to 91 per cent. Apart from reducing costs, shallow ploughing should also reduce other deleterious effects associated with the high salinity and low pH that are common in many subsoils of the brigalow region.