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Aeration for sports fields is a basic but important routine maintenance technique during the season. The benefits are to improve the air and water exchange between soil and air, to make better usage of fertilizer, to reduce water runoff and puddling, to improve turf rooting and thatch breakdown and to loosen bare spots in prepping the soil for seeding.
The procedure leads to reduced soil compaction, richer turf cushion, and better resilience and tolerance to usage and weather conditions. Without aeration in heavy-compacted clay soils found in some regions of the country, you can’t expect good turf development.
In general, the simple fact is that optimal root growth requires adequate air supply. If the grass roots do not have adequate room to grow, the turf will never achieve its potential. Aeration also controls the thatch layer. Thatch can prevent water and nutrients from penetrating as far as the root zone and cause the root zone to become more shallow and closer to the surface, thereby less tolerant to dry or hot conditions. Thatch is also an excellent breeding ground for harmful insects and disease organisms. Aeration allows the soil microflora to break down the thatch into nutrients and new living soil.
The trampling of many feet upon your exquisite turf is of course your challenge. Pore spaces in soil are important because of the oxygen they contain. When these spaces get compacted, the roots lose oxygen. The compaction can also reduce root elongation. Core aeration is an effective practice to loosen soil, reduce compaction, open the thatch and allow moisture and air in, increasing microbe activity to break down the thatch.
Before aerating a field, be sure the grass is actively growing, for the obvious reason that a dormant grass is not going to grow and quickly recover. Aeration does cause a certain amount of turf stress. Fields are generally aerated in multiple passes (in different directions), so it is a good practice to time the aeration with other turf amendments, like fertilizing and adding lime.
Tines may be mounted on a rolling drum or in a vertical method. Spoons are mounted on a disc or wheel. Hollow metal tines and open spoons remove cores. This procedure is obviously planned around game usage, as it will create an uneven surface less than ideal footing. Because of this, core tinning is perhaps best employed when the field is not played on for two weeks (for cool season grasses) and one week (for Bermudagrass), provided the cores are removed or broken up. Most sports field aeration is accomplished with 3 inch deep tines with three fourths inch diameters. Hollow tines pull up one-quarter inch to one-inch cores. This relatively shallow aeration, while loosening the soil within the three inches, can compact the soil below. Deeper tine aeration (10-12 inches) is excellent for heavily-compacted fields and improve a field’s drainage.
Solid tines of 3-4 inch long are more ideal for in-season maintenance. However, the holes created by solid tines, particularly with repeated use, will cause soil compaction and hinder drainage.
This method is touted because it employs streams of water under very high pressure to make small holes, so small that it doesn’t look like the turf has been aerated. Soil amendments can also simultaneously be injected during the aeration. The newest take on this system is the same idea but using air instead of water.
The consensus on aerating sports fields from the experts on sport field maintenance seems to be to not use a single method of aeration, but a variety of methods (solid and core tining, but also at various depths) and take advantage of the new aerating technologies.
What’s the first thing you should do when you take over maintenance of a turf field? “Pull soil samples and find out what’s under the grass,” is the advice of Jim Mueller, athletic field manager for Hall-Irwin and turf manager for the Colorado Rapids soccer team and assistant turf manager at Folsom Field, where the Colorado Buffaloes play football. “Once you know what the soil composition is, you can start planning on how you are going to change the soil profile,” Mr. Mueller says.
Now that we know your fertilization program is based on soil testing, how often should you test your soil? The answer, in general, is once a year. However, if you have sandy soil, the experts recommend testing at least twice a year—that’s because sandy soils do not hold nutrients well. The soil test is best done in late winter before the spring growth begins. It only requires digging samples 6 in. deep at random locations. It’s also a good idea to take one of your samples from a particular problem area. The lab will get the results to you in a couple of weeks, revealing the levels of phosphorous, potassium, calcium, magnesium and the pH level. Nitrogen levels are not usually reported because those levels change rapidly, however, the lab will recommend application rates of nitrogen, along with the aforementioned elements. If you have sandy soils, you’ll also want the lab to report on what micronutrients are present.
The ideal pH balance for turf is slightly acidic, 6.5, because it maximizes nutrient uptake. The superintendent should know that many nitrogen fertilizers with repeated application, particularly water-soluble elements like ammonium sulfate/nitrate and urea, slowly lower soil pH. Liming agents raise pH; fertilizers containing sulfur lower it. The experts advise using a slow-acting lime agent (calcium carbonate, magnesium carbonate or dolomitic limestone) because they are effective longer. Beware of faster-acting lime because it can cause foliar burn. To prevent foliar burn, lime should not be applied during hot and humid conditions. Ideal temperatures are when the daily highs are around 50° F or a little below. To avoid foliar burn, it is also generally advised not to apply more than 40 lbs. of liming per 1,000 sq. ft. The pH balance in sandy soils will react quickly to lime, but the effect is short-lived, requiring regular application to maintain the ideal pH.
The heavy use of sports fields necessitate a well-defined fertilization schedule. For warm season grasses, the primary growing time is late spring to early fall. For cool season grasses there are two growth periods: late winter to late spring, and late summer to late fall. While it is obvious to fertilize turf when the grass is actively growing, the roots of cool season turfgrass grow even when there is no leaf growth. During this time, fertilizing can benefit root development and store carbohydrates.
The first fertilization is normally applied in the spring and disseminates three vital nutrients: nitrogen, phosphorus and potassium.
Sandy soils are generally more deficient in phosphorus and potassium and may need a complete source all year around; heavy clay soils often require mostly nitrogen after the first application of the spring. Plan your fertilization program for the rest of the growing season based on your annual soil or tissue tests.
Potassium is critical to enhancing stress tolerance, so many sports turf managers now apply nitrogen and potassium at 1:1 ratios, particularly on sand-based fields where potassium leaching can be a problem. Phosphorus helps to promote root development, so it is important to ensure that adequate levels are present during the period when root development is taking place, i.e., in mid-summer for bermudgrass, spring and fall for cool season turf.
Iron is an important micronutrient to sports fields. A liquid application of iron brings rapid greening without concomitant shoot growth that would require additional mowing. The green-up is temporary (10-14 days). The iron is not mobile within the plant and will be mowed away during the next clipping.
Liquid iron is often mixed into a tank with pesticides or plant growth amendments to keep the chemicals from yellowing the turf.
Fertilization for bermudagrass, the most common warm season sports field turfgrass, should be applied in the hottest months, i.e., when the plants are growing the most. A typical field needs 5-6 lbs. of nitrogen per 1,000 sq. ft. each year. The first application is done two weeks after the spring green-up is complete. Apply .5-1.0 lbs. at this time, followed by four applications of 1 lb. 30 days apart during the summer. In mid-September or early October make a final application of .5-1.0 lbs. It is recommended that the October application include 1-2 lbs. of potassium to help winterize the turf.
Francisco Uviña, University of New Mexico
Hardscape Oasis in Litchfield Park
Ash Nochian, Ph.D. Landscape Architect
November 12th, 2025
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