Changes in soil physical properties after one pass of a sugarcane haulout unit

Field trials were established at different locations within the Herbert River area near Ingham in North Queensland to assess the ratooning ability and yield of sugarcane after a wet harvest. Treatments consisted of harvesting under dry conditions and then applying 50 mm of irrigation, followed by no traffic (control), traffic of a haulout unit directly over the harvested row (traffic treatment), and traffic as above with the application of further irrigation to maintain wet soil conditions (traffic + water treatment). Undisturbed soil cores were collected from the row before harvest and after treatment imposition to assess the change in soil physical properties due to traffic. Soil cone resistance was also measured. Soil physical properties changed significantly after traffic with increases in soil bulk density and soil cone resistance and decreases in saturated hydraulic conductivity. The greatest change occurred in the top 20 cm of the profile. Yield at one site was significantly reduced after traffic and the effect was enhanced in the presence of water after traffic. It is suggested that to maintain good soil conditions in the row all traffic should be restricted to the central part of the inter-row. One way to achieve this is to match crop row spacing with equipment track widths.