With proper, professional, site management, there are a few areas where pneumatic soil excavation with an AirSpade can be extremely effective for the professional arboriculturalist.
Air Tilling
Trees and shrubs suffering from shallow soil compaction – typically due to pedestrian use or vibrations caused by vehicular traffic – or lacking vigorous root growth due to poor topsoil quality, are ideal candidates for air tilling.
Since most of a tree’s roots proliferate near the surface where they have the best access to oxygen and nutrients, air tilling is excellent at promoting robust and uniform root growth. If it’s necessary to affect soil to a depth greater than 15cm-20cm, it’s possible to combine air tilling with other methods such as radial trenching or vertical mulching.
While the tree-health benefits of air tilling alone (decompaction and aeration) are significant, this method is often used for soil augmentation as well.
Radial trenching
Radial trenching with an AirSpade is done to modify soil composition, improve aeration, and encourage root growth to moderate depths, typically 25cm to 30cm or more, and is especially effective when trees have highly stratified or shallow depth of viable soil or anaerobic conditions.
Additionally, this application can be useful in planting areas where minimal disturbance is desired.
Vertical mulching
Vertical mulching with an AirSpade is done to de-compact and augment soil deep into the tree root zone.
This application is especially useful in areas with poor drainage, with shallow or impervious soils, or shared by perennial or ground-cover plantings where minimal disturbance is desired.
Aeration and soil amendments from vertical mulching can encourage roots to grow deep into the soil profile, improving the tree’s stability and the volume of viable growing medium.
Because vertical mulching affects the deepest soil profile, it is recommended for sites with shallow soil depth, hard-pan, anaerobic conditions, or other types of poor growing soils.
Root collar excavation
Trees commonly suffer when the grade is set too high against their root flare or root collar. This can occur when trees are planted at the wrong elevation or when trees subside due to improper compaction below the root ball when they are planted. Alternatively, root collars can be buried over time due to the accumulation of mulch or soil around the tree.
Whatever the cause, harm to the tree from grade set above the root collar can be long lasting and should be remediated through root collar excavation (RCX) with an AirSpade. Symptoms of this condition include:
• Rot or infection of bark at the base of the trunk
• Growth of roots that are too high relative to the natural root flare, and
• Girdling roots, which constrict the root flare and tree trunk.
Girdling can also occur on urban sites where roots have limited room to grow or have encountered compacted or anaerobic soil conditions. Use of AirSpade excavation allows tree root collars and girdling roots to be excavated with minimal damage to the tree. Once uncovered, a certified arborist can easily identify roots that need to be removed or trained.
Root pruning
AirSpade excavation is safe to the tree’s roots and a highly efficient method to perform exploratory excavation to locate existing roots and utilities. Almost any site-work operations – including the building of foundations, pavements, drainage infrastructure, and utilities – present ideal opportunities for AirSpading and root pruning.
Proper root pruning will encourage future growth and minimise negative impacts to structures or utilities.
Once the existing roots have been excavated, a certified arborist can easily determine the best places to make clean cuts using a hand pruner.
Bare rooting and transplanting
Bare rooting with an AirSpade can be applied to perennial, shrub, and groundcover plantings.
This is a preferred method of transplanting because of its efficiency and ability to preserve fine root systems. Furthermore, bare rooting small plants is often required during more extensive root-zone treatments such as aeration and decompaction or other site-work applications.
Use of an AirSpade can significantly reduce trauma to the tree.
Urban tree soil replacement
It may be desirable to partially replace the soil around a tree’s root zone in an effort to enhance the tree’s health and lifespan.
This application is ideal for tree plantings with root zones extending underneath pavement and those that have poorly suited or limited soil volume, or where pavement is proposed to be added or replaced within an existing root zone. Similarly, this may be applied to trees planted in high-use lawn areas (for example within parks or campus landscapes,) where soil replacement is desired to improve lawn durability and health.
Learn more about AirSpade and its uses and benefits at knightpneumatics.com.au.