WHAT AERATION REALLY MEANS TO YOUR GRASS

SOIL = a complex medium of organic and inorganic materials that provides water and nutrients for plant growth and development; a substance most land life depends on.

IDEAL SOIL = The area where your turf's roots are (or your trees' roots, or your vegetables' roots...) would contain available moisture for 5-8 days, yet water would not stand on the surface for more than a few minutes following a heavy rain.

The Colorado State University Cooperative Extension says: "Soil compaction is the primary factor limiting plant growth in urban soils."

The answer is aeration, but aeration does a lot more than you think! 

WHY IS AERATION SO IMPORTANT? (Besides the obvious advantage of good drainage...and good drainage isn't really the result of poking holes in the dirt!)

Soil's ingredients are organic (dead and decaying matter, air, water, living organisms) and inorganic (minerals.)

Inorganic materials are sand, silt, clay particles and gravel.

Organic materials range from 2% to 4% of total weight of the soil. Air and water fill the gaps between larger particles. Since healthy soils are alive with life forms and their remains, there must be an abundant supply of oxygen available for the organisms present. A typical soil supporting rich vegetative growth and serving as a host for insects, worms, and microbes is full of pores. This pore space should be at least 50%, with 25% occupied by air and 25% occupied by water.

The ability of soil to hold air depends on soil particle size and how well the particles pack and cling together, forming a solid mass. Clay particles are the finest, then silt, and sand and then gravel is the largest. The particle size of clay is 0.005mm or less. Since it's so small, it can pack very closely together, thus eliminating all of the air and water. This virtually eliminates the ability of the soil to support life! (Ever tried to grow anything in pure clay?)

Another factor is that when air enters the soil it contains both oxygen and carbon dioxide. Normal respiration by plant roots and soil microbes depletes the oxygen content and increases the carbon dioxide content. If the soil pore space is reduced, the carbon dioxide does not diffuse properly and you end up with anaerobic soil (no oxygen, lots of carbon dioxide that is toxic to plant roots) and then you REALLY can't grow anything in it.

Compacted soil can retard the ability of plants to use nutrients. Nutrients may be present in the root zone, but may not be available to the plant in saturated soil, or compacted soil, or soil with low biological activity. (Remember, living organisms in the soil need oxygen, so compacted soil reduces biological activity.)

Excess sodium (usually from your water source) can compact soil and keep the turf from using the nutrients in the soil.  Sodium contributes to compaction because it's positively charged, while clay is negatively charged. The sodium smashes the clay together, causing compaction.  Excess sodium also limits the nutrients available to the plants because sodium occupies the exchange sites (surfaces of soil particles and organic matter where nutrients are) and displaces other nutrients like calcium, magnesium, potassium, sodium, hydrogen and ammonium.  An extraordinary property of SoilTech (that you will never get with mechanical aeration) is that it removes sodium to a level below the root zone.  When the sodium is out of the way, the plants have more nutrients available.

Kansas State University lists the benefits of aeration:

• Loosens compacted soil

• Improves water infiltration

• Increases oxygen supply to roots

• Releases carbon dioxide

• Encourages new, deeper root growth

They also state "Restricted air movement into the soil reduces health and vigor of the turf."