Over time, the soil beneath our lawns can become as hard as a brick due to soil compaction. This reduces pore space and increases soil density.
When there is no space between particles, the movement of air, water and nutrients in the soil decreases. Water does not infiltrate in to the soil and runs off site. Turf suffers as roots struggle just to fill basic plant needs. The best way to combat compaction is with aerating.
Aeration opens channels in the soil through which air, water and nutrients can move more freely. Typically in ideal conditions, soil with good structure allows water to move into soil (infiltration) and then move through soil (percolation). This movement of water in improved with aeration. Hard soils soften when there is increased space between soil particles. Good soil structure is important for nutrient uptake by the plants, root growth and soil water recharge after a long hard drought.
Most soil compaction occurs within the top 3 inches of the soil profile. Compaction may result from heavy equipment traffic, the layering effect of differing soil textures when you top dress a lawn, or repeated tilling or aeration to the same depth. Many times we call this a plow pan in the soil. Check for soil compaction by using a soil probe, shove, blunt rod or screwdriver to see how hard the soil in a specific area.
If you need to aerate, use an aerator that pulls plugs of soil using hollow tines. There is a type of aerator that is made of spikes, but the effect of aeration is limited and not as effective. When you do aerate, make sure there is enough soil moisture so the tines go through the soil fairly easily, but you do not want to aerate when the ground is too soft right after a soaking rain. If the soil it too dry, the aerator will just dance across the lawn not penetrating into the ground.
Aeration is best for the lawn when it is actively growing. So for fescue, fall or spring is ideal. For Bermuda or zoysia grass, the summer is ideal. Aerating is a practice that can be done once a year or once every other year.
In extremely compacted soils, simple aeration may not be enough to fix the problem. In that case, a total lawn renovation may be needed.
If you have questions about when or how to aerate your lawn, just give me a call at the office.
Michael Wheeler is county extension coordinator for the UGA Cooperative Extension in Hall County. You can contact him at 770-535-8293, www.hallcounty.org/extension. His column appears weekly and on gainesvilletimes.com/life.