Management of compaction during harvest of Pinus plantations in Queensland: III. Preliminary investigation of the potential for selected soil parameters to predict rut compaction

Abstract

An assessment has been made of the potential of three soil parameters to predict compaction risk in the coastal lowlands of south-eastern Queensland. The experimental strategy involved: (i) operating a ground-based harvesting/extraction system in low-soil-strength conditions to achieve a range of rutting depths; (ii) assessing pre—and post-compaction soil moisture, cone penetration resistance and shear vane resistance; and (iii) investigating the relationships between both pre—and post-compaction characteristics of these soil parameters and observed rut compaction.

The magnitude of rut compaction was positively correlated with pre-compaction soil moisture content and negatively correlated with pre-compaction penetrometer resistance and pre-compaction shear vane resistance. Soil moisture appeared to be the most sensitive of the three soil parameters tested in discriminating between rut compaction depths, and cone penetrometer resistance the least—though differences between the three were modest. The ability of the three soil parameters tested to discriminate between different levels of rut compaction decreased greatly as average rut depths increased above 5 cm. Rut compaction prediction models based on these soil parameters would therefore provide a much higher degree of confidence in predicting rut depths ≤5 cm than in predicting ruts depths ≥10 cm—the level used for controlling field operations in Queensland.

Development and calibration of rut compaction prediction models for use in the coase-textured soils of the coastal lowlands in south-eastern Queensland are discussed.