Managing Soil, Not Turf, Keeps Fields Green for Park Authority

(Conservation Currents, Northern Virginia Soil and Water Conservation District)

Bob Studholme takes soil sampleTurfgrass Specialist is Bob Studholme’s title at the Fairfax County Park Authority (FCPA). But that might not be the best description of what he does. “I don’t manage for the plant,” says Studholme. “I’m all about managing soil. If the growing media is chemically balanced, biologically active, and well-drained, you’ll have a healthy, dense stand of turfgrass.”

Studholme has been with FCPA for more than 25 years. He started by managing athletic fields at two parks and then moved over to golf courses where he was superintendent for 17 years. In 2000 he became the FCPA’s turfgrass specialist, writing and implementing turf programs for 295 athletic fields covering 280 acres. He also oversees contracts that provide turf management services for fields at Fairfax County’s middle and elementary schools.

Managing turfgrass in Fairfax County is tough, explains Studholme. “Geographically, we’re in the Transition Zone. We’re too far south for cool season grasses to thrive during our typically hot summers, and we’re too far north for warm season grasses to not go dormant or even survive some winters.”

The climate problems are compounded by poor native soils. Physically, he says, there is too much silt and clay, and chemically there often is too much magnesium and too little calcium and potassium to support healthy turfgrass. High magnesium makes the soil really tight.

“We can’t change the climate or the physical properties, but we can change the soil chemistry and improve the biological activity,” he said.

How does he do it? “Soil testing is the cornerstone for everything I do,” he said. He takes soil samples on all 295 FCPA fields every two years and sends the samples to a lab in Ohio. Contrary to what many turf managers and homeowners expect from a soil test, Studholme is not looking primarily at pH levels. “pH is very important, but looking only at pH—percent hydrogen—is not the way I do it. If you adjust calcium, magnesium, potassium, sodium and other trace mineral levels, the hydrogen level will adjust as a result.”

Before he applies anything to the turf, he aerates the soil. “The biggest key to soil management is aeration. Soil microbes need oxygen to proliferate. Bacteria, fungi, algae, protozoa, and other organisms are the microbes that make up the Soil Food Web. Their activity produces plant-available nutrients, degrades thatch, and helps make the soil permeable.”

Once he gets the soil test results, he is ready to apply products. Ideally, he wants to see soil base cation (positively charged molecules) saturation ratio of 68% calcium, 12% magnesium, 5% potassium, less than 2% sodium, 3-4% trace minerals, and 10% hydrogen in base saturation. Sufficient levels of phosphorus and sulfur, which are anions (negatively charged molecules), are also an important part of his program.

When chemical balance is achieved, the soil “opens up” and the need for fertilizer is lower. Studholme promotes the use of natural organic fertilizer. He applies fully composted poultry litter blended with kelp, dry humates, molasses, and rock minerals to “feed the soil.”

After Studholme implemented the soil-based turf management program at the Burke Lake Park golf course, annual fertilizer requirements dropped by two-thirds. With improved soils, the golf course became more resistant to drought and disease. Water and fungicide use was reduced by 50 percent. Studholme expects similar results for most athletic fields, especially the ones with irrigation.

His biggest challenge is sustaining turfgrass on the soccer fields. “No matter what we do, the barrage of soccer cleats will compact the soil and tear up the grass,” he said. “There is a limit on how much play our athletic fields can take without deterioration of the turf.”

Studholme uses his turf management program on his own lawn. He tests the soil to ensure it is chemically balanced and uses high calcium limestone if there is a calcium deficiency. He says the yard lime from most garden stores is high in magnesium, which exacerbates soil problems. He applies fertilizer in minimal amounts twice a year, a half-pound (per 1,000 sq. ft.) of nitrogen in the fall and a half pound in the spring. Once every two years he uses an herbicide for broadleaf weeds. He mows the grass high, keeping the blades at 2.5 to 3 inches. “The higher you mow, the better the root mass,” he says.

Studholme claims to have the best lawn in his neighborhood and that he achieved it with the least amount of effort. “Unlike my neighbors who are slaves to their mowers and spreaders, I’ve got plenty of free time.” That comes in handy for the president of Woodbridge Little League.

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