Environmental Quality | University Research | Raleigh Lawn Care

By Ryan Walsh | Student, North Carolina State University

Many factors effect drainage from turfgrass. Soil slope plays a role in how the excess water will run off the land and the rate at which it will run off. A factor that can restrict run off or leachate is the turfgrass cover. Turfgrass that is well established and covers the ground well shows a dramatic reduction in runoff and leachate by the way it can filter and suck up water and nutrients. Rainfall, of course plays a role in nutrient losses based on the rate and quantity at which water is applied to the turf and how quickly it is absorbed or run off. Lastly, the soil type will have an influence on how water is infiltrated, based on particle sizes, and how nutrients are potentially lost due to many factors including the CEC.

The use of natural organic fertilizers (i.e. manures and composts) are shown to be resulted in greater phosphorous loss on a percent applied P basis whereas; the more soluble synthetic organics (i.e. UF and biosolid) result in greater Nitrogen loss. To help reduce runoff, a dense stand of turfgrass growing on the soil is highly effective in removing water from the soil. This helps to reduce runoff and leaching by reducing soil moisture. Evapotranspiration is typically turfgrass’ largest source of water removal which allows water and nutrients to be sent through the plan and released straight into the atmosphere. When there is excessive rainfall in winter and saturated soils, this can cause excessively high nutrient concentrations and losses. Sources with high solubility (i.e. NH4NO3) produce higher NO-3- N concentrations in leachate than less soluble sources. Adding a buffer is shown to directly affect the amount of N runoff, as the buffer increases, the N runoff decreases. Buffers are one of the easiest ways to eliminate the threat of contaminants entering into the water systems. When establishing a turfgrass, the combination of little ground cover, high application rates of soluble fertilizers, and frequent irrigation can create favorable conditions for runoff and leachate. Bowman et al. found that greater N losses were much higher when turfgrass roots were shallow vs. deeply rooted turf. However, despite high runoff concentrations, mass losses are generally greater in leachate.

Based on their conclusions, I would make sure to first establish buffer zones around the turf / area to be fertilized by at least 50 feet. Second, I would need to take soil samples to make sure that you apply fertilizer as needed. Fertilize with the correct type of fertilizers that best fit the application. Then, if establishing a new turf, watch the water input on the soil to make sure that run off and leaching is kept to a minimum because surely without a good turf establishment losses can occur much greater; sandy soils will allow for greater infiltration while clayey soils will infiltrate slower as a result may cause more run off. You must be aware of all of these factors when managing turf to keep losses to a minimum and the environment healthy. Well managed turf can be a very effective and environmentally safe system to prevent water quality issues.

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