Crop and Soil Environmental News, November 2004

'Leave' Them Alone: Lawn Leaf Management

While we enjoy the beautiful colors associated with fall foliage, we also realize that most of those leaves will soon be on the ground. At this time of year, many turf managers quit managing grass and shift their focus instead to leaf management. In some situations, leaf removal by way of blowing, raking, or vacuuming is essential because of turf use (e.g. golf course turf where finding a ball in leaves is next to impossible). However, the treatment and/or disposal of these leaves is a time consuming and costly process. In some areas, it is actually illegal to place bagged leaves at curbside for pickup due to restrictions on placing lawn waste in landfills. Are there reasonable alternatives in leaf management?

The answer is yes. And the technique is one that many of you have used for years -- leaf mulching directly into the turf. There are several university research reports detailing how leaf mulching affects turf performance. In almost every instance, the results show that chopping up deciduous leaves as part of a regular mowing schedule is an effective means of managing them without harming the turf. A research report entitled "Leaf Mulching Effects on Turf Performance" from Purdue University turfgrass researchers Zac Reicher and Glenn Hardebeck can be accessed online at http://www.agry.purdue.edu/turf/report/1999/page24.htm. This report does an excellent job detailing the responses of a perennial ryegrass lawn turf to the application of up to 4000 lbs of maple (Acer sp.) leaves/acre in a single application. Mulching the leaves had no undesirable effects on turf quality or color, growth, thatch accumulation, soil pH, weed populations, or disease pressure. While the leaves did not prove to be a substitute for proper N fertilization practices, the overall assessment was that mulching was overall very positive and economical.

There are some important considerations before using leaf mulching in turf as a method of leaf disposal. While mulching mowers are preferred because of special deck and/or blade designs to mulch clippings, almost any rotary mowing unit can suffice. However, think safety first. Use the rotary mower for leaf mulching, not as a stump grinder or chipper/shredder. Inspect the site and remove sticks and limbs before mulching. This greatly reduces the chance that you or someone else can be hurt, and improves the performance and life of your mower. Wear safety goggles and an air mask over your mouth and nose to protect from debris and dust. Mulch leaves when they are suitably dry rather than soaking wet. While this causes more concerns with dust, dry leaves are much easier to mulch and cause less wear and tear on the mower. Finally, consider the limitations of the mower itself. There is only so much leaf matter that can be handled at one time, so use some common sense regarding how many leaves can be effectively mulched in a single mowing event. Sharpen blades more frequently (to improve the mulching operation and to address the likelihood that your blades will still likely be hitting some debris) and clean filters (air and other) more regularly.

Many pine trees are also shedding a season's worth of needles during the fall as new growth emerges. Unfortunately, mulching is not an effective way to dispose of pine needles because of their size, shape, and composition. Pine needles are highly resistant to microbial breakdown, and even if they are chopped into smaller pieces, they remain physically intact for months. While resistance to decomposition precludes pine needle disposal by mulching, the durability of pine straw is one reason it is so popular as a landscape bedding mulch.

Consider utilizing your rotary or mulching mower as a leaf disposal tool this fall. Mulching leaves directly back into the turf has proven to be a cost (and time) effective means of leaf disposal, does not negatively impact turf performance, and helps reduce the volume of landfill waste.

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