Review of existing knowledge on subsurface soil compaction in South Africa

Abstract

This paper reviews the existing knowledge on subsurface compaction in South Africa. Subsurface soil compaction is an extremely widespread and serious problem throughout all nine provinces of South Africa and neighboring countries like Botswana, Namibia, Swaziland and Zimbabwe. It is indeed a widespread serious problem throughout the whole of Africa. Subsurface compaction has very serious implications regarding crop yields and quality, disease incidence and water use efficiency. Various research methodologies are used to study subsurface soil compaction. Soil factors determining the susceptibility of a soil to subsurface soil compaction include particle size distribution, soil organic matter content and clay mineralogy. Negative impacts of subsurface soil compaction include, increased soil strength and resultant negative impacts on root development and top growth, impacts on plant nutrient uptake, water use efficiency, reduction of hydraulic conductivity and inhibition of soil aeration. Management factors that cause or aggravate soil compaction are uncontrolled vehicular traffic, large numbers of shallow secondary tillage operations, cultivating or traversing wet soil, and high tire pressures. Subsurface soil compaction can be alleviated by ripping, the application of controlled traffic, refraining from conducting operations on wet soil, and the use of the lowest possible tire pressures.