Cover St ory
Aerification of Heavy Clay Soils By Charles H. Peacock, Ph.D., NC State University
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Above: Photo 1. Intact soil cores from an aerification. Photo 2. A recently aerated turf surface, showing the distance between coring holes.
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lmost forty years ago, Dr. James Beard published his now well-known textbook titled Turfgrass: Science and Culture. This classic work combined the science behind what was known, and not known, at that time about techniques in turfgrass management with an understanding of how real-life application of management techniques should be used. It set the stage for prioritizing turfgrass-research programs and brought a focus as to how these must be structured to fill the gaps in knowledge and application. This is important because Beard pointed out that once we establish a turfgrass area, we expect it to be usable for many years (if not decades) without a need for major renovation. With use, however, turf areas are subject to wear and compaction, especially under specific soil, climatic and traffic conditions. This adversely affects soil properties as well as the grass plant itself by limiting the root system. In order to optimize conditions for turfgrass growth so that recovery from wear can be rapid and the turf is most resistant to pest pressure, then cultivation of the soil profile must be included in a sound turf-management program.
The importance of aeration Cultivation is defined as the tilling of the soil profile without damaging the turf so severely it cannot rapidly recover. This requires specialized equipment and techniques. Of the cultivation techniques available, coring (often called aeration or aerification) is most often used. 18
The effects of compacted soil on the ability of turfgrass plants to grow include the following: • Increased bulk density, resulting in decreased gas exchange (decreased oxygen levels). • Roots have trouble penetrating the soil. • Greater surface runoff. • Greater heat conductivity. The goal of a coring or aeration process is to improve the exchange of air and water between the atmosphere and soil (see Table 1). Air exchange is important since the root system requires oxygen in order to properly function, while allowing excess carbon dioxide (which builds up from the respiration process) to Table 1. Benefits of aerification. • Decreases bulk density (reduces compaction). • Increases gas exchange (for better rooting). • Improves water infiltration and reduces runoff. •O pens the soil to allow incorporation of materials such as fertilizers or lime. • Enhances seed-to-soil contact (during seeding). • Removes thatch. • Penetrates compacted subsurface layers. • Prepares an existing turf for renovation.
TENNESSEE TURFGRASS August/September 2012 Email TTA at: tnturfgrassassn@aol.com