SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/714252
50 SportsTurf | September 2016 www.sportsturfonline.com Q&A with Dr. Grady Miller Questions? Send them to Grady Miller at North Carolina State University, Box 7620, Raleigh, NC 27695-7620, or email grady_miller@ncsu.edu Or, send your question to Pamela Sherratt at 202 Kottman Hall, 2001 Coffey Road, Columbus, OH 43210 or sherratt.1@osu.edu Professor, North Carolina State University Not your average garden Q : I have been buying garden fertilizer (10-10-10) for our school's bermudagrass fields and they have been looking pretty good the past couple of years. Is that bad? Someone told me I should have a soil test run so I could buy a different fertilizer. Can you explain what they meant? — North Carolina A : I would be hard pressed to be too critical of your fertilizer practices if your fields have looked good and performed well the past 2 years. The issue of picking the best fertilizer and how it is applied may be more an issue of efficiency. From a nutritional perspective you want to maximize turfgrass quality while minimizing your fertilizer inputs. You also need to stay within your budget. The suggestion to use a soil test to change your fertilizer source was an insinuation that additional information may allow you to get similar results with fewer inputs. But there is more to this story. Somewhere in the history of gardening it must have been stated that garden plants need balanced fertility to be productive. In response, the fertilizer industry has been marketing and selling "triple-8", "triple-10", and "triple-13" fertilizer to gardeners for decades. Modern plant nutrition research has dispelled this myth surrounding balanced fertilizer use for gardening, but the demand for the products remains. Since many people buy fertilizers from garden centers and these products are comparatively inexpensive, they will invariably be used to fertilize turfgrasses. In the past few years there has been a new chapter written in this story. A number of states have put regulations in place that limit the sale of lawn fertilizers with phosphorus (middle number on a bag of fertilizer). This is because the primary nutrient polluters of water are nitrogen and phosphorus. Since pollution of water can occur with small amounts of phosphorus, the industry has largely decided to dramatically reduce or remove phosphorus from fertilizers that are intended to be put on turfgrasses. The most commonly found fertilizer designed for turfgrass use has low/ no phosphorus and a high percentage of slow-released nitrogen. This is considered environmentally good. On the other hand, a fertilizer that contains N, P, and K is often recommended in extension publications if no soil test data is available. Using a complete fertilizer is viewed as a preventative application. In other terms, applying a complete fertilizer prevents one of the three most common fertilizer nutrients (N-P-K) from being a limiting nutrient for growth and performance. In many cases the only place that one can still find phosphorus-containing fertilizer in a retail outlet is in the gardening section. Remember that just because phosphorus is not sold in turfgrass fertilizer in some regions does not mean that it has become unnecessary for plant health. Your turfgrass may or may not need phosphorus, but how do you know? A soil test can determine the levels of major plant nutrients, including phosphorus, potassium, calcium, magnesium, etc., available to the plant from the soil. The tests then provide site-specific fertilizer recommendations (optimum levels) based on the amount of the nutrients in the soil. This improves efficiency and can reduce the total expenses spent on fertilizers (it can also increase fertility cost if there are significant deficiencies). For example, if phosphorus levels in the soil are found to be sufficient, the recommendation will indicate that no phosphorus is needed. This conserves natural resources and helps protect water and the environment. There are a few other points related to soil testing to keep in mind. First, many plant responses to stresses (drought, disease, cold, traffic, etc.) may be related to plant available nutrient supply. Knowledge of soil/plant nutrient status can guide fertility practices that may help you manage stresses. Second, soil tests can often be used in the diagnosis of problems when there are nutritional influences. Third, a soil testing fee is a nominal cost compared to potential fertilizer savings. There are a number of different soil test philosophies and test methods that are used today. My suggestion is to find a reputable service lab (state or private) and discuss with them your results in detail so you understand what the numbers mean. Use this data along with your experience on site as a basis for fertilizer selection and application. So I would also encourage you to not treat your turfgrass like your average garden. Get some soil test information and treat it like a sports turf surface. Knowledge of soil/plant nutrient status can guide fertility practices that may help you manage stresses.