ATC's Turf Science Seminars, March 15 & April 15 (ターフサイエンス セミナー2010)
Bermudagrass White Leaf

Relieving Turfgrass Stress: Part 2, Air in the Soil

Aerify-habu-cc In a previous post I wrote about relieving turfgrass stress by ensuring that grass blades are cut cleanly. After ensuring that mowers are sharp and are mowing the grass at the optimum height, what is another way to relieve turfgrass stress?

Turfgrass stress can be reduced by ensuring there is enough air in the soil. Golfers don't like aerification and greenkeepers are often under pressure to skip aerification because on the surface the greens appear to be fine. But when there is not enough air in the soil, roots do not grow, and grass without roots does not provide a good playing surface for very long.

black layer in turfgrass soil profile

The black layer in the soil above is because of waterlogged conditions. Roots are not growing in the saturated soil, but can you see the old aerification hole in the center of the photo? Do you see that vertical strip through the soil profile with no black layer? Do you see the white roots growing in this aerification hole? When there is enough air in the soil (and I would suggest that about 25% air by volume is a good starting point), the roots can grow. The reason for hollow tine core aerification is to physically remove organic matter from the soil while allowing more air into the soil, and the reason for solid tine aerification is to introduce air into the soil. Organic matter in the soil creates small pores that hold a lot of water. Healthy turfgrass creates large amounts of organic matter, and this organic matter must be managed in order to maintain adequate air in the soil. For a look at some more photos of roots and aerification practices, click here.

The solution to the black layer problem or to the problem of too much organic matter in the soil is really a simple one: make more air in the soil. This is done by keeping the soil as dry as possible, by physically removing organic matter, by regularly topdressing with sand to maintain aeration porosity, and by venting or other types of solid tine aerification, as shown below.

So the next time you suspect your turfgrass may be suffering from too much stress, think of ways that more air can be introduced into the soil. More air in the soil is a sure way to reduce stress and improve turfgrass conditions.


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