Dr. Darby McGrath
Vineland Research and Innovation Centre
Based on earlier research results which pointed to the negative impact of compacted urban soils, Dr. Darby McGrath’s research project was designed to improve tree survivability in highway and urban environments. After five years of research and four years of direct testing, deep ripping and the addition of organic matter has been proven as a method of remediation of urban soils to ensure the long-term survival of trees.
It has been demonstrated that trees can survive beyond the critical post-transplant window in unremediated soils; mortality increases in years three and thereafter. Therefore, remediated soils provide the right conditions for trees to become established and survive without aftercare. The goal was to develop a remediation technique that can be modified depending on the end users’ soil quality (e.g. bulk density). Based on several sites sampled throughout Ontario and Alberta, a soil remediation calculator was developed that estimates the amount of organic amendment required to bring the soil bulk density below root limiting thresholds for trees.