In response to the early concerns of landfills prematurely reaching capacity, research was commissioned to look at the different ways of dealing with waste lawn clippings. Composting became an overnight craze in the 1970's. I remember this time well because I was a high school student working nights and weekends in the Lawn & Garden Department at a local Ace Hardware store. Plastic compost bins began to show up on my shelves and I was the one assembling them! By 1980 hand cranked compost bins and composting food (nitrogen fertilizer) were being introduced in small one pound bags. In 1985 mulching kits began to show up on retailers shelves. Snapper was one of the first companies to offer such a kit. At the time, we were instructed by manufacturers to instruct buyers to mow every third day or at least twice a week to prevent the clumping of grass during periods of fast growth, adhering to the 1/3 rule, or not to remove more than 1/3 of the blade at any mowing. Sluggish retail sales of complete mulching mowers that cost twice as much as the bagging mowers needed a "sales pitch" to stimulate sales. This is where one of the myths that grasscycling returns back the equivalent of 1 lb nitrogen per season begins.
Since then, grasscycling or mulching proponents have always sold mowers by using the claim that mulching returns 1 lb of Nitrogen back to the soil/1000 Ft² thus allowing homeowners to reduce fertilization needs by one application per year. Folks, Green Industry representatives lied to us about the benefits of mulching mowers by twisting research data to create talking points with the specific intention of causing us to buy overpriced mulching lawn mowers. I believe I've found the smoking gun and the old research data to support my claim.
Out of desperation I guess, and pressure from local landfills and even mowing manufacturers, universities took these early talking points and cited them so often in their own publications that they began to believe the sales pitch, never questioning whether or not the initial experiments actually replicated field conditions of mowing a lawn. What I mean is, when you use a mulching mower, where do your clippings end up? They end up spread out over the top of your grass stand, right? I wanted to know which study was the first to suggest that mulching reduces fertilizer demands. Most important, how was the experiment set up and what protocol was used to make this determination? Does it represent a true mowing situation?
As a lawn care fertilization professional for 35 years, I had never seen a visual difference between lawns mulched and lawns bagged. I've polled golf course superintendents and none of them see a visual or health difference between fairways where clippings are left to lie and the aprons, approaches or tee boxes where clippings are bagged and removed. In my experience, mulched lawns were deeper in thatch because in the real world, the lawns are mowed much taller (once a week) versus the recommended every third day, resulting in more non-decayed biomass (dried grass blades, ie. hay). Mulching increases thatch and I have 35 years of experience to prove it. Mulching increases the incidence of disease because the disease spores are left on the surface to reinfect new emerging grass blades, requiring fungicide applications.
The earliest published research dealing with the amount of Nitrogen that can be returned by turf grass clippings was conducted by Dr. Kelly Kopp, Asst. Professor of Turf and Water Conservation at Utah State University titled "Decomposition Rates and Nitrogen Release of Turf Grass Clippings". Read it for yourself!
, this is the data and the time period that the industry latched onto and ran with! I don't oppose the finding of Kelly's research because if you place lawn clippings under sod to decompose, they will return nitrogen. They so desperately wanted us to divert green waste by buying a mulching mower, that they lied to us about a study by twisting the truth. In doing so, they did a major disservice by tarnishing the good image and reputation of lawn clippings. Currently, we all have a negative opinion of lawn clippings, well except for me and those that are using a BioPac'r to make bank!
1997 Research
Here are the most important excerpts on how the experiment was set up. You be the judge if the method of this experiment replicates a real life mowing situation?
Step 1 worth noting: " first-cutting of clippings were harvested from field plots and placed into litter bags for the determination of decomposition rates and Nitrogen (N) release patterns. -In other words, how much N is returned to the soil from the lawn clippings decomposing in the litter bag?
Your first Question, as was mine, is what in the world is a "litter bag"? So I called the researchers and I was told that a litter bag was an empty tea bag that they then stuffed with lawn clippings.
Step 2 worth noting: Ten litter bags were placed into and under the thatch layer of each plot and the bags were retrieved from the field after 1, 2, 3, 4, 5, 7, 9, 11, 13, and 16 weeks."
My next question as should be yours is, how did you get the litter bags into (inside and under the thatch layer)? Again, I was told a slit was cut and the litter bags were then slid under the sod between the soil's surface and the thatch layer.
Last Question, does your mulching mower deposit the lawn clippings Over the Top of the turf or UNDER the thatch layer? The only way we can be expected to get our lawn clippings under the turf is to remove it, cut it off, and scatter clippings and then re-sod it! Not very practical, and totally impossible in the lawn mowing world. This critical experiment changed the reputation of lawn clippings.
The conclusion of the research paper says that more research is necessary to determine decomposition and N release rates for different grass species under varying management conditions when clippings are returned. This study clearly shows, however, that the decomposition of grass clippings (when placed in a litter bag and slid under the thatch layer) provides rapidly released N to turfgrass, but we all know this experiment does not reflect real mowing.
Myth or Fact?
Returning lawn clippings is equivalent to applying 1 lb of nitrogen/1000 ft²/season? Answer - Myth.
This experiment was never intended to answer the question of how much nitrogen is returned when using a mulching lawn mower. It was answering the question of how much nitrogen can be returned when the clippings are inserted under the thatch which placed them in contact with soil microbes. Soil microbes are not found on top of the thatch layer where clippings are deposited.
Long story short, the research data was twisted into a false narrative to sell lawn mowers.
- Mulching still saves time unless you mow twice a week as recommended.
- Mulching does not reclaim the billions of gallons of irrigation water as stated in "Have your Grass and Feed it Too!".
- Mulched lawns will never look as good as those lawns bagged during high growth periods, read "My Truths about Mulching Lawn Mowers".
- Mulching disregards a valuable natural resource that cumulatively, can feed a million additional head of cattle without ever adding an additional acre of farm ground into production and assisting in "Reinventing Golf Course Ownership".
The New Image of Lawn Clipping'$
- The value of lawn clippings in dollars and cents when converted into Lawn Clipping Silage™ is so profitable, that the additional revenue generated will more than pay for the cost of labor to bag the clippings with additional profits retained.
- Landscapers still don't have to go to a landfill and they are no longer leaving money lying on the ground after they leave a freshly mowed lawn.
- Lawn clippings have been demonstrated in an adaptive feeding study to be a very valuable feed supply when ensiled into Lawn Clipping Silage.
- When we mow and collect the clippings from a lawn with an active disease we actually carry off the disease spores, reducing the inoculate, which decreases the life cycle of lawn diseases. In doing so we can prevent the application of additional pesticides in the form of fungicides.
Since we are not really saving the cost of an application of nitrogen, maybe you want to consider making a bunch of cash from your lawn clippings. There is now an alternative to Grasscycling that generates revenue. It also offers a new and improved image to grass clippings that is resonating with landscapers, consumers and farmers worldwide.
If you are already collecting lawn clippings, there is an alternative to smelly composting or the cost of labor to take and pay to throw away lawn clippings at a local landfill.
So, lawn mowing companies, don't be afraid to Bag Those Lawn Clippings!
Until Next Time..
