Cover Story
Are Mulching Mowers Necessarily Better? By Grady L. Miller and Raymond K. McCauley
Introduction Recycling lawn clippings promotes the retention of plant nutrients on site and may enhance turfgrass quality. It seems reasonable to assume that smaller turfgrass clippings will filter down through the turfgrass canopy to the soil surface and enhance the onset of decomposition and provide an environmental benefit. From a consumer’s perspective, fewer clippings visible on the turfgrass surface can result in a more uniform, attractive turfgrass canopy. It is this point that is often used as a selling point for using a specific mower or a method of mowing. But there has been no scientific study to show if one mowing method results in a higher quality turfgrass or not. Rotary lawn mowers have decks that house one to three horizontal rotating cutting blades. The decks of these mowers are designed to lift, cut, and discharge leaf tissue through side or rear orifices. Many mowers offer a mulching option which closes discharge orifices resulting in completely enclosed decks. For some mowers, decks are mulching-specific. In principle, mulching-specific decks cut clippings multiple times before discharging the ‘mulched’ debris beneath the unit into the turfgrass canopy. This suggests mulching units should produce more visually appealing turfgrass stands as a result of fewer clippings on the turf surface immediately following mowing. Some of our previous work that evaluated cut quality of different mowers on multiple coolseason grass species and various mowing modes (mulching, side discharge, and bagging) resulted in inconsistent post-mowing turfgrass quality between various mower setups (Miller et al., 2016). Specifically, it was found that mulching units deposited excessive clippings on the turf surface and decreased turfgrass quality compared to side discharge units. However, this study did not compare clipping sizes from side discharge and mulching mowers but just assessed biomass on the surface. The objective of the study presented in this article was to evaluate the effectiveness of mulching mower operation to reduce clipping particle size compared to traditional side discharge mower operation.
Mowing Units
Controlled mower testing.
14 North Carolina Turf gr a ss
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To accomplish this objective, a field study at the Lake Wheeler Turfgrass Research Laboratory in Raleigh, N.C. was conducted to assess the influence of mower setup on post-mowing clipping size. Each mowing unit was used on actively growing El Toro zoysiagrass maintained at 2.5 inches and tall fescue maintained at 3.5 inches. Turf species were chosen due to their popularity among North Carolina homeowners.
January / February 2024
