Turfgrass sod is better at slowing water runoff and preventing erosion.
Seeded slopes show 10 to 12 times greater runoff than sodded slopes during high rates of irrigation or rain. In tests, water soaked into sod at a rate of 7.6 inches per hour, compared with 2.3 to 2.5 inches per hour into seeded slopes. When nitrates are found in nearby ground water, turf fertilization is sometimes wrongly accused. In fact, tests show that growing turfgrass sod plants absorb most fertilizer nitrogen almost immediately and very little in the way of applied nutrients escape the grass itself. The small amount of phosphate in turf fertilizers is quickly ‘fixed’ by the turfgrass and soil, contributing to plant growth that has many ecological benefits.
Sod helps groundwater replacement.
Under average rainfall, an acre of turfgrass sod provides an average of 600,000 gallons of water replacement each year. A typical 150 acre golf course located in the Northeast, for example, will recharge the water table with 90 million gallons of rainwater and snowmelt a year. This golf course would use about 9 million gallons of water a year for irrigation, providing a net gain of 81 million gallons for water table replenishment.
Microbes in turfgrass sod help break down chemicals.
The use of pesticides on turf has caused concern. Yet, tests show that dense turfgrass sod slows runoff velocity and allows water to infiltrate where soil microbes degrade the chemicals. Pesticides watered in after application stay in the thin layer of thatch in healthy turfgrass. The root zones of the mature grass plants also provide excellent conditions for more complete herbicide degradation.
Turfgrass Lawn Color: Can too much green be bad?
The key factors affecting the green color of turfgrass, beyond its natural color, are Nitrogen, Sulfur and Iron (Manganese plays a minor role). For most turfgrasses, the ‘ultimate’ dark green color is achieved with Nitrogen fertilizer. Yet, achieving that ‘ultimate’ green with excessive Nitrogen can carry a heavy price – in added fertilizer costs and potential damage to your lawn.
Excessive Nitrogen causes higher evapotranspiration rates (the rate at which your lawn gives up its moisture to the air). This causes it to use up the water in the roots’ vicinity faster and requires watering more frequently to keep the turfgrass plants’ moisture in balance. It also restricts root development, so roots may not be able to reach available water.
Excessive Nitrogen accentuates the effects of disease and insect injury to grass plants.
Too much Nitrogen can cause roots to dieback and decrease in size and number.
Reduced recovery from stress
Too much fertilizer exhausts the turfgrass plants’ carbohydrate reserves, restricting the turf’s power to recuperate, and reducing its ability to endure heat, drought, cold and winter desiccation.
How much fertilizer is too much?
The Nitrogen level at which negative effects occur depends on the turfgrass species and cultivar, soil texture, amount and frequency of rain and irrigation, and whether grass clippings are removed or remain on the turfgrass. As a rule-of-thumb, fertilization rates greater than 1 pound of actual Nitrogen per 1,000 sq. ft. per application exhaust turfgrass plant carbohydrates.