Several years ago, a lawn service customer of mine told me about a neighbor he once knew who annually had a large pile of fertile, composted soil delivered to her house following an aeration. She labored for several days spreading a thin layer all over her lawn filling in the aeration holes.
Her lawn maintenance philosophy he described as being very simple and logical. “You have to feed the soil!” she always proclaimed to her envious neighbors. He honestly admitted her lawn was always the standard for a beautiful lawn.
While neither of us put a name to this process at first, I have come to learn it is called top-dressing-- a process of adding soil amendments to an existing lawn. (Think: Golf course greens)
This woman's story came to memory last spring while playing with my children in our back yard. I noticed my lawn was hard as a rock, thin, had several dry spots, and was painful to run around on with bare feet.
Although I routinely aerated, fertilized, watered, and mowed the grass, the soil beneath my lawn was mostly clay by the evidence on the aeration plugs. It wasn’t lush like it once was.
I thought: Where was the black organic matter the landscapers tilled in years ago prior to sod installation?
Being a science teacher, I decided to conduct an experiment in which I put “feeding the soil” or top-dressing, to the test on three different lawns.
Pretty soon after, neighbors next door to the top-dressed lawns started calling me and saying things like, “Whatever you did to your lawn, do it to mine!” and “Living next door to her yard makes my yard look terrible now. Put me on your schedule for next year.”
Top-dressing transforms lawns, has more benefits than fertilizing only, and gets noticed.
So, How Does it Work?
What are we feeding in the soil through top-dressing? A beautiful lawn is the result of a soil food web beneath thriving with microorganisms and water absorbing organic matter.
Compost naturally has a high nitrogen content, feeding your lawn directly, making it grow thicker. What is more important, however, is compost contains beneficial microorganisms capable of feeding your grass through the process of Nitrogen Fixation over long periods of time. Using top-dressing mixtures with sandy loam added to the compost creates a more porous soil, that breaks up clay, allows for better infiltration of water, air, and nutrients, potentially developing a deeper root zone.
The truth is, “feeding the soil” with a good compost and sandy loam mixture is the most logical and beneficial lawn maintenance program Coloradans can perform to our clay rich and organic poor soil.
Top-dressing will develop a vigorous soil food web beneath an older lawn and be capable of holding more water. Filling aeration holes with professionally blended soils reduces compaction. Top-dressing is being recognized by many as an environmentally safe alternative to synthetic fertilizers.
The benefits of top-dressing lawns are many and should be considered by everyone interested in setting the standard for a beautiful lawn in their neighborhood.
Benefits of Top-dressing Lawns:
*Feeds the micro-organisms, macro-organisms, and grass
- Compost is loaded with microorganisms and has a high Nitrogen content
- Microorganisms continuously feed your lawn through Nitrogen fixation
- Nutrients are released slowly
- Compost adds macronutrients (N, P, K)
- Compost adds micronutrients (Mg, B, Zn, Cu)
- Organic Matter builds up and improves soil over time
- Earthworms naturally aerate when consuming organic matter at surface
*Increases moisture retention, reduces irrigation, conserves water
- Fewer, but deeper, waterings of lawn hydrates the organic matter
- Increasing the organic matter by 1% increases the ability of an acre of soil to hold 16,500 more gallons of water (GA Urban Agriculture Council)
*Breaks up clay, reduces compaction
- Compost and Sandy Loam naturally creates a more porous soil allowing for better infiltration of water, oxygen, nitrogen, nutrients, and fertilizer
- Potentially develops a deeper root zone
- Grass responds better when fertilizer can reach the root zone
- Reduces nutrient loss due to runoff
*Levels your lawn, evens out lumps
- Dragging the lawn following top-dressing fills in aeration holes and depressions
- Level athletic fields and lawns reduces injuries
*Resists drought, drains better
- Water soaks in and doesn’t sit on the surface and evaporate after watering or precipitation
- Deeper waterings of lawn encourages roots to go deeper to obtain water during heat waves
- Reduces surface crusting
- Less water runoff
*Stimulates lawn to produce new shoots
- Increases root development
- New growth thickens lawn which prevents weed seeds from taking root
- Microbes inhibit plant pathogens and turf diseases
- Reduces lawn pests and fungal diseases
- Reduces the need for chemicals to treat lawn weeds
- Improves tolerance to wear and tear
- Enhances the growth of micro-organisms that feed on thatch
- Overseeding thin lawns germinates and grows very well in compost