Author Topic: Introduction to Aeration  (Read 2181 times)

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Introduction to Aeration
« on: April 27, 2011, 11:36:40 AM »
Introduction to Aeration

Aeration is not a frequently used practice on lawns unless the soil is compacted or requires a deep application of compost. For athletic fields, aeration is a very important cultural practice that must be included in any program. Aeration is the mechanical process of relieving compaction. Compaction is the biggest enemy of turfgrass. Generally speaking, our non-forest soils here in the northeastern United States are 25 percent air, 25 percent water, 45 percent minerals and 5 percent organic matter. Compaction is the result of repeated compression of the soil through mechanical pressure, and the end result is that the air in the soil is expelled. As the soil particles get pressed together and the air spaces are closed, available oxygen is reduced or eliminated.

Most plants, turfgrass included, grow best in an aerobic environment, that is, in a soil that is 25 percent air. Oxygen is important to sustain the soil biology, and a thriving microbial population gives us good root growth and exchange of nutrients.

There are, however, plants that thrive in a compacted soil, and to the turf manager they are considered weeds. Broadleaf plantain and pineapple weed are two examples. In the absence of a penetrometer, they can be very good indicators of compaction.

Lawns can become compacted for a number of reasons, but on an athletic field, compaction happens on a regular and repeated basis. The heavy use and sheer number of children and athletes using the fields contribute to compaction rather quickly.

The compaction must be relieved by aerating the soil mechanically. An athletic field can be aerated any time the turf is actively growing. It is recommended that fields be aerated several times a year. The process can to some degree be put on a schedule, but it is better for the turf manager to use his or her judgment. Soil conditions and composition, excessive rain, play on a wet field, intensity of use and season of the year are all factors to be considered. Each field may be different and on a different schedule, but in general, you should be aggressive when it comes to aeration.

When the microbial population is high and the soil is stable, with high organic content and dense turf roots, the biological activity and beneficial organisms in the soil work as our allies, helping to keep the soil naturally aerated. This is not to say that biological activity replaces aeration, but rather the need is reduced and mechanical aeration does not have to be done as frequently.

Some type of cultivation (core aeration) should be done before applying compost and seeding. Fall is the best time to start an aggressive organic turfgrass program, beginning with core aeration and other cultural practices and continuing the core aeration three times per year.