A REVIEW OF SOIL DEGRADATION AND MANAGEMENT RESEARCH UNDER INTENSIVE SUGARCANE CROPPING

Grey soils are the most extensive group of soils in the dryland cane areas of the South African sugar indusry and comprise about 60% of the total area under cane. Soil factors limiting the yield potential of these soils include low water intake due to surface crusting, soil loss through erosion, low available moisture capacity, soil organic matter loss, acidifi­ cation and waterlogging during wet seasons. Many current ratoon cane management practices such as interrow ripping, burning of crop residues at harvest, harvesting under wet con­ ditions and using heavy infield transport, are incompatible with the physical, chemical and biological properties of these soils. Recent research initiatives into the main soil degrada­ tion processes, as well as improved managementpractices for reducing physical damage to soils, are reviewed. Soil man­ agement strategies based on crop residue retention, nutrient recycling, minimum tillage, ridge tillage, cover crops and intercropping, will help to conserve soil and water more ef­ fectively, increase soil organic matter, improve fertiliser use efficiency and reduce physical damage to soils during har­ vesting.