Top Dressing with Compost

The Short Version on Top Dressing with Compost (see below for lots of juicy details):

What is Top Dressing? Top Dressing is the process of spreading a layer of high quality soil evenly over an already established or struggling lawn to add needed nutrients and increase the soil quality and depth.

Why should you do it?

  • Austin has poor soil. Rocky and high in clay. Have you ever dug in your yard?
  • Nutrients and moisture retention.
  • In summary: makes water wetter, fertilization more fertilizy and grass greener.

When should you do it?

  • Spring and early fall when grass is still growing but the temperature is cooler.

What do we use?

  • Really good stuff. The secret sauce includes: 50/50 combination of loam and compost and moon rocks. (see below for details…and there are no moon rocks)

Anything else?

  • If is best to couple this service with Aeration. BONUS: Add winter rye in the fall to have a lush green lawn through the winter.

Long Version:

Primer on Soil – and why you should care.

Austin area soils are famous for their poor quality.  Ask any avid local gardener and they will give you a list of their soil woes.  Ultimately what it comes down to is we have very little soil, the soil we do have is rocky, and it’s full of clay. 

This poor soil is hard on lawns.  There is a huge list of things lawns need to be happy, but several of the big items are sunlight, air, water, and nutrients.  Soil quality can have a big impact on three of these four items.  Plants absorb water, nutrients and even air through their roots.  As a consequence, soil quality can have the biggest impact on the health of your lawn.

A good soil will have a lot of organic mater in it to provide nutrients, will have the capacity to hold water, but is also able to drain well allowing the soil to dry out.  A soil’s ability to do those three things are impacted by the type of soil, and the soil structure.

Soil Types:

There are three main types of inorganic material that all soils are made of.  These particles are called clay, silt, and sand.  Clay is the smallest particle size, and is “sticky” – the chemicals that form clay bond to things easily.  Silt is only slightly larger than clay, but doesn’t bind to things like clay does.  Sand is the largest particle of the three, and drains very well and resists compaction.  An ideal mix is called loam, and is a mixture of all three in roughly equal proportions.  Combining loam with organic material creates the perfect soil. 

Because our soil consists of mostly clay, with very little organic material, it doesn’t drain very well, and has very few nutrients.  The clay binds with water as soon as your irrigation kicks on.  The top layer of soil will saturate quickly, preventing water from soaking deep into the soil.  If you continue to add water, it will run off the soil rather than soak in.  It is one reason we are so prone to flooding in our area.

The clay also binds to nutrients like fertilizers, but binds in such a way that those nutrients aren’t available for plants to use.  Clay is a bit greedy.  And it binds to itself.  It creates a compacted layer of soil that excludes air and is difficult for roots to grow through.  On a hot summer day in Austin the soil can often feel harder than concrete.

Fixing Clay soil:

Unfortunately, there is no quick fix to change clay into perfect soil.  What we focus on is changing the soil structure, rather than try to change the type of soil.  You improve the soil structure by breaking up the compacted clay and adding organic material.  This gives the clay something useful to bind to, and it is a material that combats every problem that clay causes.  The organic material will improve drainage, resist compaction, and both holds and releases nutrients and water. 

Clay soil mixed with a lot of organic material is transformed and behaves more like an ideal loam soil.  Water can seep deeper into the soil, it resists compaction, and plants love it.

In nature, organic material is added to the soil slowly, over decades.  Plants grow and die, leaves fall, and other organic materials fall into the soil.  As this natural organic material decomposes, it is incorporated into the soil by worms, insects, fungus and bacteria.  The same is true in our yards.  Grass clippings, leaves, and other debris are typically mulched by our mowers and the organic material gradually becomes a part of the soil.

And that is where top dressing steps in.  It is the best way to add organic material to a lawn.  Top Dressing is a shortcut, where a thin layer of compost rich soil is spread over the lawn.  Our compost soil blend is a mix of 50 percent compost and 50 percent loam – basically a perfect soil. 

What is compost?

Compost can consist of many things, but it is a general term for organic material that has already started the road to decomposition and incorporation into soil.  It is not a raw material.  It has been processed by bacteria and fungus (100% natural process,) into a form that is immediately useful and beneficial. 

Compost and other organic materials are used up over time.  It’s basically what the plants live on, but bacteria and fungus also continue to break down the organic material.  At the end of the process we end up with a material generally called Humates.  Humates are amazing for plants and soil.  Water soluble humates are often included in fertilization programs (including ours!).  But it takes tons of compost to produce a small amount of humates. 

What this means is that organic materials and compost need to be added to the soil regularly.  People generally add tons of organic material to their planting beds without even thinking about it.  In beds we call it mulch, and it adds a lot of organic material.  Ever wonder why your grass seems to grow better in your planting bed than your lawn? Now you know.

Top dressing with compost adds those same much needed organic materials directly to the lawn.  We don’t mix them into the soil, mostly because it would damage the lawn.  But, generally the grass will grow up through the top dressing and the compost is incorporated directly into the lawn.  Over time, worms and insects will help mix this thin layer in with the existing soil.

Our Top Dressing Service – What to expect

What we do:

We spread a thin layer of perfect soil over the entire lawn.  We calculate our estimates and train our crews to spread a quarter inch layer over the lawn.  Because it is spread over the top of an existing lawn, it will be loose and not 100% even, but because it is a loose material it will eventually settle down between the leaves of the grass.  This process goes faster with regular irrigation or a light rain.  The water helps wash the mix down into low areas where it is most needed.

We generally spread the compost by hand.  We have investigated spreading machines, but have yet to find a solution that works better than a well-trained crew.   When we do, we may switch, but for now we appreciate the flexibility that hand spreading gives us.

Top Dressing can be a tricky service to complete.  The grass needs to be short.  The weather needs to be warm enough that the grass is growing, but not so hot that a layer of soil will smother and bake the ground.  This gives us a service window in the spring, and a smaller window in the fall.  This service is very weather specific, so we keep our eyes on the forecasts before sending crews to complete this service.

How often should you top dress:

Top dressing can be an expensive service depending on the size of your lawn.  This means that most people don’t top dress their lawn as often as they should.  Top Dressing is a service that should be completed as often as possible.  If you have the budget, top dress twice a year.  If not, top dress as often as you can afford to.  The more you are able to top dress, the healthier your soil will be, and the better your lawn will look. 

It helps to think of top dressing like mulch.  It’s a big job that should be done every year.  I you can’t do it all at once, break it out and tackle it in pieces.

When is top dressing most useful:

We try to emphasize this service for specific conditions where it is extremely useful.  New neighborhoods benefit from this service more than an established yard.  In new neighborhoods builders and developers typically remove any existing native topsoil, and replace it with a rock and soil blend that is perfect for constructing houses.  This soil blend is great at keeping foundations from cracking, but it is sterile and has zero organic mater in it.  New yards and lawns struggle for years as the soil slowly improves.  Adding compost speeds the process and injects life into new yards.

Neglected yards and landscapes also need top dressing badly.  If your lawn hasn’t been top dress or fertilized in a decade the soil will be in horrible shape.  Typically, the grass gets thin, the soil becomes brick hard, and worms are nowhere to be seen.  Top Dressing will help kick the natural processes back into gear, and will get everything growing again.

It is also useful in lawns that are stressed or damaged, or even struggling with disease.  Improving the soil will help improve the health of the lawn overall.  It’s the equivalent to hot chicken soup when you’re sick.  If your lawn isn’t in the best health, top dressing can help.

What makes us different:

At Top Choice we like to do things right.  Other companies provide a similar service, but most typically add an eighth of an inch of straight compost over the lawn.  We’ve tried that, and we don’t like the results.  We use a quarter inch of a compost and soil blend instead.  Why? Because it works. 

Part of the reason we top dress is to build a deeper soil bed, and a straight compost will eventually decompose into nearly nothing.  Think of it as a very slow release fertilizer.  It does a lot of good, but in the end, you still have a thin soil bed.  Using a 50/50 blend of loam and compost gives you the same amount of compost as the other company, but you also get a thin layer of loam which isn’t going away.  Grass loves that loam. 

Basically, by using a mix that includes loam we are addressing Austin’s thin soil issue, as well as improving the quality of the soil. 

Complementary services:

There are some beneficial synergies when you combine top dressing with other services.  Some are obvious, but others aren’t as easy to recognize.

The first is lawn mowing.  This one seems odd to mention, but it makes a difference.   If your lawn is being cut correctly and your grass clippings are being mulched back into the lawn (including every lawn we mow), top dressing will give your yard an added boost.  The mulched grass clippings will sit on the surface of your soil until they decompose.  This is a good thing.  Adding compost over those clippings speeds the process up a lot.  The compost already contains the bacteria and fungus needed to decompose the clippings quickly.

The second synergy is with aeration.  Aeration breaks up the soil, loosening the clay by pulling plugs of soil out of the lawn.  Top dressing immediately after aeration replaces those plugs of soil with loose, compost/loam soil that does wonders.  Because the lawn is full of holes, the compost and loam gets much farther down into the soil.  The results are similar to a service called “Vertical Mulching,” which focuses on adding organic material as deep into the soil as possible.  It is a very good thing.

A third synergy is with winter over-seeding.  Adding a thin layer of incredible soil over a lawn right before adding grass seed does incredible things.  The good soil will be in direct contact with the delicate emerging grass seed, and will make your winter lawn absolutely amazing.  You are basically giving the seed everything it needs to grow well and become a thick lush lawn as quickly as possible.

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