Refereed Article A fresh look at Operational Soil Compaction
Shane McMahon , Robyn Simcock , John Dando and Craig Ross
The study aimed to quantify how much of a setting was adversely compacted during ground-based harvesting of an Orthic Pumice soil. Travel of harvesting machines was monitored using Global Positioning System (GPS) receivers fitted to the cabs. The resulting machine pass map was used to identify sites with 0, 1-3, 7-12 and 20-50 passes where physical properties of soil were measured. Two-thirds of the cutover was trafficked with 20% receiving more than 20 passes. Visual assessment classified the site as 87% disturbed, 6% showing deep disturbance (topsoil removal), and less than 0.2% rutted. One to three machine passes had no significant effect on soil physical properties. Although 20-50 passes led to a 60% decrease in the volume of air-filled pores, critical levels were not reached. Cone penetration resistance was >3 MPa below 34cm depth over 38%) of the cutover and below 18 cm depth over 20% of the cutover.
