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.
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50 SportsTurf | January 2016 www.sportsturfonline.com We use zero-turn mowers for our bermu- dagrass athletic fields because they are more economical and we can mow a lot of the town's fields pretty quickly. The cut quality is not so great, especially in the fall. Do you have any suggestions on improving the cut quality considering the mowers we are using? North Carolina Y our question reminds me of a story I recently read in a magazine. The author was about my age and he was telling a story about mow- ing the family yard when he was a teenager. One time when he came around the house on the mower he heard his dad shouting to him about doing the job "half-fast." He was a bit surprised to hear the com- ment because he had the mower engine fully revved and the accelerator pedal to the floorboard. He did not think he could mow it any faster. I chuckled reading the story because I can remember a few times when my father shouted to me while I was mowing. There was no mistaking my father's terms of dis- pleasure. Following a few of those episodes, I learned to do a better job. Slowing down was just part of the equation. Over the past couple of years I have been researching the parameters that represent "cut quality" and how it may be influenced by rotary mower design and use. We looked at numerous individual factors but the desired end result was always a uniform turf on top with mini- mum to no visible clippings on the surface. Our research found that many factors can influence cut quality with rotary mowers, including mowing speed. Most of our work has been with tradi- tional lawn tractors, but in 2015 we ran a series of tests with zero-turn mowers. Since many people do tend to operate zero-turn mowers faster than lawn tractors, we used mowing speed as one of our primary test parameters. In our studies mowing at 3 mph resulted in a 16% improvement in cut quality compared to mowing at 5 mph. So to improve mowing quality with your zero-turn mowers you may want to start by clocking mowing speeds and slowing down the operators if necessary. Paint lines on the turf 50 feet apart and use a stopwatch to time them in action. It should take about 11 seconds for a 3 mph rate and only about 7 seconds for a 5 mph rate. Of course different mowers may perform differently at different speeds. Individual mower set-up can also impact cut quality. Time should be given to set up mowers according to manufacturer's operating manual. Mower deck levelness and rake should be checked and adjusted appropriately. Blades should be balanced and sharpened frequently. That interval will largely depend on mower use, turf density, and soil conditions (sandy soils are harsh on mower blades). I have noticed that some mower blades just seem to last longer than others, so regular inspections are necessary. It is a good habit to check the mower blades each day before the mower is used. Mowing height can also influence turf quality after mowing. This is especially true when the ground is uneven. Zero-turn mowers often have fairly wide decks (72 inches is pretty common) and do not have a great deal of float. As the mowing height starts to move below 1.5 inches with a wider deck, the likelihood of scalping goes up. This is made even worse if mowing at a high speed since the mowers have a tendency to bounce more. For this reason you may have to adjust the height of cut to match the levelness of the ground in addi- tion to slowing down. The poorer quality of cut in the fall is often due to the shorter day length caus- ing the bermudagrass to "stretch" more looking for light. Even with frequent mowing at the same height of cut it is not unusual to start having some scalp- ing come mid-September. This is very hard to totally avoid, but you may try slightly bumping up your mowing height to counteract the plant's tendency to elongate in the early fall. Most modern zero-turn mowers are easily adjusted for different mowing heights. Lastly, if your mower has a mulching deck design and you are using it in that mode, then you may experience lower cut quality. Our experience found that a turf manager interested in maximizing cut quality would be much better off using a traditional side-discharge (and the appro- priate side-discharge blades) if they are mowing very dense turfgrass. Set up your equipment appropriately and adjust for your given mowing condi- tions. If a mowing cycle is missed then adjusting the height of cut up may be neces- sary to get back on a schedule and maintain a high quality of cut. The same may be necessary in the early fall. With a little adjustment to the equipment and how it is used, you can achieve an acceptable quality of cut with zero-turn mowers and not be accused of doing it "half-fast." ■ ST Cut quality using a zero-turn mower 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 Even with frequent mowing at the same height of cut it is not unusual to start having some scalping come mid-September.