Organic Matter for Lawns Topdressing

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Organic matter for lawns is important in achieving healthy green grass. Whether you use organic or chemicals to fertilize your lawn, an organic matter level around 10% will make your efforts a lot easier.

What is organic matter ? It can be described as compost, humus, organic material, rich soil or food for microbes. However you define it, the importance of lawn compost can’t be overlooked.

Organic matter for lawns is one of the most important factors in having healthy natural soil. Even though the humus in soil is usually only about 5%.

Your soil structure should be:

    25% air
    25% water
    45% mineral
    5% living and dead material


Organic matter consists of living and decomposing plant and animal material. It’s pretty amazing how even that small 5 % can affect the soil and the life in it.

More than 5% of lawn compost in your soil is great but our soil test will tell us if that is necessary.

It retains moisture while improving drainage, alleviates compact soil, provides nutrients to plants, buffers pH and most of all it provides microbes, arthropods, earthworms “and their food”. The list goes on and on. Scientists are continually studying the benefits of organic matter for lawns.

Compost Is the Best Source of Organic Matter for Lawns


What we’re interested in is the finished product of composting and that is called humus.

What is compost ? Its appearance is dark and coffee like. It feels light and crumbly. Its smell is rich, earthy and healthy and it should not be warm or hot to the touch.

Void of branches or undecomposed material, it should also be alive with earthworms and other arthropods.

If soil humus smells bad at all, it wasn’t made correctly and should be avoided.

Our natural lawn care store has all your composting needs.


What is Organic Matter ?

Some compost are made of manure some with leaves and grass clippings sometimes people throw in anything that will break down and decompose and then there is lawn compost with a combination of all of these. Whatever the source is, the most important thing is that the compost is made correctly.

organic matter compostI don’t think most people have the resources to compost enough for topdressing a lawn. When you’re top-dressing your grass you use approximately 1 square yard of organic matter per 1000 square feet. So if your yard is say 5,000 square feet obviously you need 5 square yards. Do you know how many leaves have to break down to get 5 yards of compost? Me neither but it’s a lot more than I have.

When buying compost it’s important to look for the physical attributes we just talked about. Ask the supplier if he or she has their organic matter tested, if they do ask to see the results. If they don’t test, look for another source. See if they’ve had a biological assay done, which tests microbial populations of the compost.

Here is a great site to learn more about compost.

Another source of compost available are bio-solids

Yes, they are high in organic material but please avoid them. Bio-solids contain heavy metals including lead and arsenic, which are dangerous to children and pets. Let’s put it this way, bio-solids are everything that goes down your toilet including hormones, pharmaceuticals. If you’re not sure what the organic material source is, by all means ask the person you’re buying it from.

Sometimes finding a good supplier can be difficult but they are out there. At the very least the humus should have a regular test done as you would your soil. The pH should be near neutral, which is 7 and the carbon to nitrogen ratio at around 15 to 1. Moisture level will be higher than 40% but less than 80%.

If the sales person has never heard of pH but you think the compost is good based on its physical attributes as well as the price and location of the supplier, you may want to send it out to be tested yourself, it should be under $20.

Then go back and educate the supplier on why the test is important.

You should definitely have a compost test done before you use it. Ask around get the word out and soon than later you’ll find a good source. Soil and compost biological assay can be expensive so some suppliers are reluctant to have them done and if they have a biological assay done on the compost your lucky and don’t hesitate to pay a little extra for it. You’ll be able to meet the demands of what your soil is lacking in microbes.

 Applying Compost to Lawns is the Best Way to Add Organic Matter

Top dressing your lawn is the best way to add compost to your soil. Unless you’re starting your lawn from scratch and your going to till the compost into the soil, it’s the only way.

organic matter humusApplying compost 1/4 to 1/2 inch evenly on top of your lawn is the maximum amount you can top dress at a given time. More than 1/2 inch of humus and you’ll run into problems. A top-dressing of 3/8 inch will be equivalent to 1 cubic yard of compost and will raise the organic material in your soil by 1 percent.

Applying organic matter for lawns late summer/early autumn or late spring is optimum. If you have the opportunity to do both that’s great, the sooner you’ll reach your goals. 5% of organic matter is good but sometimes more or less is needed. A soil test should be done first to determine your CEC level. From there you will know what percentage you will need.

Applying compost to rich soil can be done any time of the year as long as the lawn is actively growing. Thoroughly aerating your lawn before top-dressing allows the humus to get deep into the earth and work quicker with minimal erosion problems.

For more discussion on top-dressing, check out our repairing lawns section!

Natural Fertilizers Are A Good Source of Organic Material

Another source of organic matter for lawns is through some organic fertilizers and feed. Though they do not offer all the benefits of compost (organic matter AND biology) they are convenient and easier to handle.


What is a Source of Organic Matter ?

  • Alfalfa meal
  • Cottonseed meal
  • Soybean meal
  • Chicken manure

Just leaving your grass clippings down when you mow, adds not only one pound of nitrogen a year but also adds “green food” top-dressing which feeds bacteria in the lawn soil.

Mulching light layers of leaves into your rich soil in the autumn is a another great source of organic matter. Being a “brown source” dead leaves feed the fungi in your lawn.

To achieve optimum rich soil and a beautiful, sustainable lawn that can naturally fight off any unwanted pests, a good diversity of soil microbes in the soil is necessary.


Organic Matter and Topdressing Video

Different soil microbes require different foods

So mixing up your applications of organic matter for lawns is really important. Just remember topdressing with compost should be your main source!


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