New topsoil vs correcting soil conditions

[godjwood]

Hi all,

This season I have worked very hard to learn how to do things the right way.

I have been getting soil tests done- it seems like I am the only landscaper doing this. Trugreen and Lawn Doctor don't even get soil tests.

When someone has a poor lawn it seems like most peoples solutions is to just deliver more topsoil and seed.

This seems like the easy way out, however more expensive.

I recently renovated a lawn. I sprayed the whole thing with round up and killed out the crabgrass. I took soil tests and received the results. Two weeks later I rented a toro dingo with cultivator attachment and tilled in all recommended soil ammendments into the top 6 inches of soil, including correct amounts of lime, phosphorous, and potassium.

I have yet to see the results, but according to the soil test I have done this correctly. And I assume using much less labor then delivering and spreading enough topsoil for 5000 ft2.

What is everyones input on this? Do you think most landscapers just put down topsoil because they dont know any better? Why does no one get soil tests? Or am I approaching this in the wrong direction?

Thank you.

[F-350PSD]

That is the correct procedure as long as you are adding your material to an A HORIZON soil. If you are trying to mix your nutrients into a B HORIZON (common when a contractor digs below the original topsoil layer and doesn't bother to replace it, very common) you will have little success growing anything at all very well. So, If it's just a poor A horizon which needs repairing then yes that is the way to go, however if it is a mix of an A and B horizons or maybe just a B horizon you need to go ahead and put down 6 inches of topsoil to have success growing quality turf. Remember soil is created over looong periods of time. The soil here in CT is over 10,000 years old and it's even older down in RI. You can't simply create a soil you can only repair it.

[greendoctor]

I will second that. In my area, I need to watch out for what is sold as "topsoil" and "topsoil + compost". That so called "topsoil is screened B Horizon soils from excavation sites or it is soil that has other problems such as pH being off, salinity, elemental toxicities and the fact that it is usually red clay. I am better off making pottery with most of the stuff. If I do need to replace growing media for a turf area, it is done with a 50-50 mix of sharp sand and compost. Why would I bring in more B Horizon soil, when that is the problem in the first place?

I always get a soil test done. I am not an installing landscaper, just an LCO and consultant. I have corrected B soils, but results are not instant and the client has to be prepared for a long process.

[Smallaxe]

Topsoil is a mixture of Clay, Sand, and Silt, with enough OM to call it "Soil" instead of "Dirt".
I also grew up learning in school that it takes a 1000 years to make 1 inch of topsoil... What they neglected to include, in their little equation, was that more than 1 inch is lost to erosion, of one sort or another, in a 1000 year period. I watch mowers picking up 1/4 inch of topsoil and bag it with dry clippings in one pass. :laugh:
In roughly 14 million years the entire land mass on the planet could be eroded down to seas level at the Current Estimated Rate of erosion.

Bottom line is adding compost to "Subsoil" will do you just fine.

Think about it... Does it make a difference if topsoil is made by rotting vegetable matter sitting on top of the soil over loooooong periods of time or if you mix it into the soil right now?

[F-350PSD]

It actually does matter because the B horizon will have much different water and air holding capacity than an A horizon because they have literally no sand and are made up almost entirely by clay and silt. The roots will have a really hard time penetrating and anchoring themselves in the B horizon and we all know that healthy roots= healthy plants. If you are going for an OK lawn but nothing special go ahead and mix in your muck and peat with the B horizon and you will see OK results. But if you want a really high quality, lush, thick, dark green lawn go with an A horizon that has all of its micro and macronutrients in line and a correct pH. You'll be amazed with the results