Assessment Of Trends In Run-Off And Sediment Yield From Catchments Under Sugarcane Production And Management Practices

Run-off is dependent on interactions between rainfall intensity, antecedent soil moisture conditions and land cover while peak discharge from a catchment is closely related to the run-off volume generated. Both run-off volume and peak discharge are drivers to sediment yield. The purpose of this study was to increase understanding of run-off and soil erosion processes from catchments under sugarcane production and various management practices (i.e. tillage and land cover). The study area was located at La Mercy on the site that now hosts the King Shaka International airport in South Africa. It consisted of four research catchments which were under sugarcane production and various management practices for the period 1986-1995. The data consisted of daily run-off and sediment yield for the same period. A comparison of run-off from the four catchments showed that effects of minimum tillage and strip planting on run-off reduction were evident while effects of conservation structures (i.e. spill-over roads and water carrying terraces) on run-off reduction were not evident. Hence, it is hypothesised that crop cover masked the effects of conservation structures on run-off reduction. With respect to sediment yield, low soil erodibility, sugarcane land cover and management practices had greater impact on the reduction of sediment yield than conservation structures while effects of catchment steepness on sediment yield were not evident. This is because soil erodibility neutralises the effects of catchment steepness on sediment yield production.