Conservation systems change soil resistance to compaction caused by mechanised harvesting

Abstract

Soil compaction in sugarcane plantation has increased in recent times due to intense mechanization of the production process and the increasing axle load of the machines. As such, there are need to evolve conservation systems which will minimize soil disturbance in sugarcane production thereby preventing soil structure degradation and maintain the soil quality, using appropriate compaction models. Thus, the objective of this study was to evaluate the impact of sugarcane harvesting operation under cover crop management systems and soil tillage practices implemented before sugarcane planting using load-bearing capacity models (LBCM). The experiment was set up in a randomised block design with three soil management systems (no tillage, minimum tillage, and minimum tillage combined with a deep subsoiler) and two crop rotations (peanut and sorghum). Soils samples were collected at three depths before and after sugarcane harvesting. The undisturbed soil samples were submitted to the uniaxial compression test, their precompression stress was determined and, afterwards the load-bearing capacity model for each treatment was developed. The load-bearing capacity models showed soil structure degradation under conventional tillage and pasture management, while there was a recuperative effect of soil structure in crop rotation management. However, peanut as a crop rotation made the soil more susceptible to compaction, regardless of soil tillage treatment. At harvest time, the soil was more susceptible to compaction under the following conditions: in the surface layer, with the use of deep subsoiling and with the use of cover crops (peanuts and sorghum). From a practical point of view, this indicates that the better soil physical condition obtained by soil tillage and the use of cover crops can be wiped out by the harvesting operation, thus traffic control actions (including soil moisture and traffic reduction) need to be adopted.