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Released: February 15, 2001 Most Kansas Lawns Need Annual Aeration MANHATTAN, Kan. -- Just walking or driving across a lawn to mow it can compact the soil. Watering the grass can squeeze out soil’s oxygen, too. That’s why many well-established lawns are suffocating slowly -- unless their owner is providing periodic help. Their soil compaction rate is even faster if lawns have poor drainage, heavy foot (paw) traffic, thatch buildup and/or crossover by heavy equipment, said Matt Fagerness, horticulturist at Kansas State University. "The problem can start if you overtill when preparing the seedbed," he added. "And, it can get worse if you let soil stay compacted into summer, because your lawn will dry out so quickly." That’s why Fagerness generally recommends homeowners aerate their lawns at least once a year. The only exceptions are people with newly seeded lawns and those with sandy soils.
"If you grow turf that develops thatch problems, you’ll need to aerate more often -- twice a year, at least," he said. "If your lawn is in clay and gets lots of use, you also will need to aerate twice yearly." (See box at right) For homeowners growing tall fescue or Kentucky bluegrass, the best time to aerate is in March, April and/or September. For those with bermuda, buffalograss, or zoysia, prime aeration time lasts from late May through July, he said. No matter the month, however, core aeration should come before seasonal maintenance chores such as fertilizing, seeding and applying pre-emergence herbicides (e.g., crabgrass preventer). Most equipment rental stores have core aerators available, the horticulturist said. The machines come equipped with hollow tines that punch and pull out a narrow core of soil, depositing it on top of the grass. "This kind of equipment isn’t lightweight. If you can’t handle a full-size tiller, for example, you might want to hire a professional to aerate your lawn," advised Fagerness, who is the turfgrass specialist for K-State Research and Extension. Soil moisture content is vital to successful aeration. Tines can’t penetrate deeply enough into droughty soils. They clog in wet soils and may not deposit the soggy cores on the lawn’s surface. Good hole spacing also is important. "If the holes are spaced too far apart, you won’t exactly be wasting your time. But, you’ll still have a compaction problem, he explained. " If the holes are too close together, that’s not as big a deal; they’ll simply remain visible for a little longer. So, you should err on the side of overdoing things, if you’re unsure about the results you’re getting." Fagerness said that achieving good spacing will require making three or more passes over the lawn, with each pass going in a different direction. The ideal homeowners should strive for is cores that are 3 inches deep and 3 inches apart. Rainfall and the lawn itself will remove correctly spaced holes from sight in about a month. "You won’t see the full results of regular aerating for about three years," Fagerness said. "But your lawn’s roots will be getting healthier, deeper and stronger almost immediately." Where thick thatch is a problem, some lawnowners fight back by power raking. "If thatch is that thick, however, they really should power rake and core aerate," he said. Thatch often is the only physical sign that a lawn needs aeration. Compaction has gone on too long when lawns dry out so quickly in summer that their "breathing" problem becomes obvious, Fagerness said. -30- K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan. Story by: |