Feature Article - March 2012
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Maintenance & Operations: Turf Management

Sustainable Turf Management
An Organic Systems-Based Approach

By Tammy York


Mowing 101

Always mow the grass at the highest setting of the mower blade, which is typically 3 to 4 inches. Longer grass blades shade the soil, which in turn prevents weed seeds from germinating, keeps the soil temperature cooler, and reduces water loss. In mowing (or any kind of plant trimming), never remove more than a third of the plant.

Use a mulching lawn mower to retain the clippings. As the mulched clippings decompose, they will return moisture and nutrients. The nitrogen from the decomposing clippings is important to the health of the soil profile.

Add a little variety in your mowing path by mowing at right angles on alternate mows. This helps promote the development of upright shoot growth as well as keeps the grass at the same height throughout.

Organic turf management started slowly but is gaining ground with more communities, cities and campuses, as well as residential consumers opting for less synthetic chemicals in their environments for the health of their children, themselves and the environment.

"Don't mow during the heat of the day, it will stress the grass. Mowing in the morning or afternoon is best. If it is over 85 degrees, do not mow," Kelly said. "The turf is already under stress from the heat, and mowing stresses the turf even more. It will go dormant, allowing sunlight to reach the ground and crabgrass seeds to germinate."

Always mow the grass with a sharp mower blade. Sharper mower blades produce a clean cut versus dull mower blades, which shred the grass and further stress it. Shredded grass loses water and is susceptible to insects and diseases.

Fertilizing

Conventional fertilizers are water soluble urea-based. These synthetic water soluble fertilizers release nitrogen on contact with soil moisture. The nitrogen begins to be released within 48 hours and has a maximum of seven to 10 days after application. The nitrogen is gone within four to six weeks after application. "In the fertilizer model, because nitrogen is being released at the seven to 10 day point, that is faster than grass can use it," Osborne said. "That nitrogen contributes to runoff and groundwater contamination. It is estimated that 35 percent of the nitrogen makes a positive impact on the grass and that 65 percent leaves the soil environment."

Organic fertilizers gain their nitrogen from seaweed, alfalfa meal, cottonseed meal, fish emulsions, corn byproducts, compost made from plant material, composted poultry and cattle manure, or composted sewage sludge. The nitrogen derived from these sources is water insoluble and is absorbed into the microbial community. Since natural organic fertilizer is water insoluble, it does not leach the nutrients and the nitrogen is delivered to the grass plant through the biomass. The full 100 percent of that fertilizer makes a positive impact on the grass.

Compost has been shown to have other benefits besides releasing moisture and nutrients into the soil. For example, composted chicken manure and composted turkey manure have both been shown to decrease crabgrass, molds, summer and brown patch, and dollar spot.