A variety of soil characteristics influence the health and vigor of trees. Soils that lack sufficient moisture are obviously problematic, as are those without enough nitrogen. Improper pH can also be troubling for trees, and reduce the rate at which they can absorb vital nutrients.
But one underappreciated soil characteristic that can influence the health of trees is the degree to which the soil is compacted. Trees obviously won’t remain stable in a pile of loose dirt, but they can struggle in soils that are packed too hard as well. Loose soil is rarely a problem, but soils in urban and suburban areas are often too compacted to allow trees to thrive.
Why Is Compacted Soil Problematic?
Normally, soil is made up of small mineral grains that are surrounded by tiny spaces (called pores) that hold water and air. This arrangement provides enough “give” for tree roots to wiggle through the grains as they grow. Additionally, the water and oxygen the roots need is easily accessed, so the tree is able to live as it should.
However, if you compress a sample of soil, you end up pressing the mineral grains together, which reduces the size of the pores around them. This means that the roots are unable to penetrate the soil, and the amount of air and water in the soil pores is sharply reduced. Trees living in these compacted soils often struggle to thrive, and they can even die because of it.
How Do Soils Become Compacted?
A variety of things can cause soil compaction, but two of the most common causes include construction activities and pedestrian traffic. The heavy vehicles involved in many construction projects often cause rapid compaction, and many soils are purposefully compacted to provide a stable base that can support the new building or home addition. But this often leads to the decline or death of any trees in the vicinity, whose roots penetrate into the compacted zone.
Pedestrian traffic is a longer-term problem, which often occurs at parks or near walkways and other places where people and pets frequently travel.
What Can Be Done to Address Compacted Soils?
If you are installing trees in a place with compacted soil, the best course of action is to break up the soil before installing the new tree. This can be done in a number of ways, and is not terribly difficult or expensive to do. On the other hand, reducing soil compaction around existing trees is trickier. One method arborists use to do so is called radial trenching, which involves the use of hand tools or high-pressured air to remove the soil around the roots, before replacing it with non-compacted soil.
Another technique that may alleviate soil compaction problems is called vertical mulching. This involves the drilling of dozens of deep, narrow holes throughout the critical roots zone, and then filling the holes back in with a mixture of soil and organic material.
Given the difficulties involved in treating compacted soil around trees, it is wise to prevent the problem entirely. One way to do so is by having an arborist establish tree protection zones before any construction takes place. This will prevent heavy equipment from compacting the soil over a tree’s roots, allowing you to avoid the problem entirely.
If you believe that your trees are suffering due to compacted soil, give your friends at Evergreen Arborist Consultants a call. Our experienced arborists can inspect your trees, diagnose the problem and recommend the best path forward. Remember, it is much easier to correct problems if you catch them early, so don’t procrastinate – get the professional assistance you need to keep your trees looking their best.