Although very different compared to cropping systems, there are a number of cultivation practices used for turf maintenance such as slicing, spiking, de-thatching and verti-cutting that have varying purposes and applications. Included with these, the practice of aeration (sometimes called aerification) most often refers to the creation of holes in the soil using a machine with either solid or hollow tines.
Solid tine aeration involves the simple punching of holes in the soil, while the hollow tine version captures and removes volumes of soil often referred to as cores. Each approach has utility for different management objectives, but hollow-tine or core aeration is arguably the best 'general-purpose' method and is applicable in the widest range of situations. In terms of importance, aeration as a management practice falls somewhere just beyond the basic fundamentals of mowing, irrigation, and fertilization.
There are numerous potential benefits of core aeration, some of the most notable are as follows:
Relief of compaction – Compressive forces such as foot or vehicle traffic can lead to dramatic reductions in total pore space of the soil. Compacted soils provide a challenging growing environment that restricts infiltration and drainage of water, gas exchange with the atmosphere, and root growth. Removal of soil cores through aeration is an important tool for restoring some pore space to the root zone and providing relief from these negative factors.
Improved gas exchange –Turfgrass root tissues require a sufficient supply of oxygen for respiration and growth. Beneficial soil microorganisms also require ample oxygen for proper functioning and robust population numbers. Aeration creates means for gases in the soil to be more effectively exchanged with the atmosphere, which promotes the cycling out of less desirable carbon dioxide the cycling in of more desirable oxygen. Aeration also promotes better moisture infiltration and drainage, reducing the potential for prolonged soil saturation and associated oxygen inhibition.
Improved microbial activity –Like turfgrass plants, soil microorganism populations normally benefit from aeration. As noted above, aeration promotes better gas exchange, improves root zone water relations, and positively impacts the overall growing environment. Healthier microbial populations perform myriad functions including the breakdown of thatch and organic matter, and the recycling and retention of nutrients in the turf system.
Management of thatch – Thatch typically accumulates when resilient plant tissues, such as stolons and rhizomes, are produced faster than microbial populations are able to break them down. Improved soil conditions from aeration help to 'tip the scales' in favor of microbes and allow better control of the rate of thatch buildup. Hollow-tine aeration also disrupts the thatch layer by physically removing significant quantities of thatch, as well as creating greater surface area for more efficient degradation.
Improved moisture infiltration – Because aeration helps to break up and reduce thatch and mat layers, and to disrupt any existing surface crusts, better site permeability and better infiltration of moisture into the root zone frequently results. More effective infiltration translates to more efficient use of irrigation and natural precipitation and reduces the potential for negative conditions such as puddling and runoff.
One of the key merits of core aeration that is sometimes overlooked is the idea of 'access' to the root zone. Bear in mind that turf is a perennial system typically maintained in a relatively undisturbed state over a period of several years. This means that the most valuable time for incorporating fertilizer, liming materials and other soil amendments into the root zone is at the time of establishment or during a wholesale re-construction event. While not a replacement, proper aeration is the next best avenue for 'opening the soil' and transmitting amendments and other materials into the root zone. Aeration also helps to promote seed-to-soil contact for more effective overseeding, which can also help with recovery from the disruption that aeration creates.
While several aeration events per year may be appropriate for higher traffic areas, especially on golf courses or sports fields, once annually is a good general guideline for many lawn and grounds areas. Lower maintenance turf areas may be aerated even less frequently. It is important to apply aeration based on need and specific management goals, as research has demonstrated that aerating too frequently, especially at similar depths, can create a 'cultivation pan' in the soil profile over time.
Remember also that core aeration is a disruptive process and somewhat of a shock to the system. Aeration should be carried out only when aesthetic considerations permit, and when favorable conditions for recovery exist. Late summer, when temperatures moderate, rainfall increases, and annual weed pressure subsides, is normally the ideal time in Southern New England. So if you haven't already, start gearing up for those core aeration projects now.
Submitted by: Jason Lanier
