The Soil-Water Cost of Heavy Machinery Traffic on a Vertosol

McGeary, Rowena (2018) The Soil-Water Cost of Heavy Machinery Traffic on a Vertosol. [USQ Project]


There has been a recent and clear trend toward the use and development of larger, more powerful agricultural machinery to increase the field efficiency and this trend is predicted to continue, at the risk of significant soil compaction. Walsh (2002) suggested the cost of soil compaction, determined as equivalent agricultural production loss is ~AU$850M per year. It is therefore important to understand the impact of soil compaction on the soil water characteristic under such machinery, which was the objective of this work. Using the John Deere 7760 (JD7760) cotton picker as a case study, a Vertosol from Jimbour, QLD was investigated for changes in soil water potential after traffic from a conventionally and a controlled traffic farming (CTF) configured JD7760. Bulk density and saturated moisture content were determined, the falling head technique was used to determine the saturated hydraulic conductivity and the unsaturated hydraulic conductivity was assessed using the HYPROP system. This allowed for the soil water availability and infiltration dynamics to be determined by HYDRUS-1D. The saturated hydraulic conductivity decreased significantly in response to traffic with the greatest relative reduction occurring in the lower two depths. Bulk density increased significantly in response to traffic, with the greatest relative increase occurring in the upper two depths. At saturation, the control surface contains significantly greater volumetric moisture content (θv) and at permanent wilting point, significantly less θv throughout the control. The θv at the permanent wilting point for the soils associated with the conventionally and CTF configured JD7760 is approximately 5% greater than the control, meaning that compacted soils retain more water at permanent wilting point, limiting plant available water. Traffic results in a changed soil-water dynamic for these Vertosol soils, whereby soilwater access is reduced as a result of compaction.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Institute for Life Sciences and the Environment - Centre for Sustainable Agricultural Systems (1 Aug 2018 -)
Supervisors: Bennett, John McLean
Qualification: Bachelor of Engineering (Honours) (Environmental)
Date Deposited: 15 Sep 2021 05:32
Last Modified: 29 Jun 2023 01:56

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