soil amendment for ornamental landscapes?

Asked March 25, 2013, 12:58 PM EDT

Can you amend a compacted clay subsoil to be a good planting medium for large scale landscapes (ex. campuses, parks, appt. complexes). During construction, it is very costly to haul off soil and replace with new topsoil. What can be done "in-place" and how effective is it in the long term.

Clackamas County Oregon gardening soil amendments horticulture

3 Responses

Can you amend a compacted clay subsoil to be a good planting medium for large scale landscapes? the answer is yes but not overnight.
During construction, it is very costly to haul off soil and replace with new topsoil. Yes it is costly and not ideal either.
What can be done "in-place" and how effective is it in the long term? add organic matter.
The problem is much more complicated than this. In construction terms dirt is just dirt no matter where it comes from. When we call dirt soil now we are looking at supporting life, plants, trees, etc. Soil is a living organism consisting of many other living organisms as well, in a stratified structure. With enough time disturbed soil will restore the stratification back to a healthy state. We can help the soil by adding organic matter and let the micro organisms turn it to what the soil needs. I have talked about not overnight and enough time well, putting that into perspective it takes years.


Thank you for your response, Randy. An addendum to the above question: I have heard from some people that adding construction sand to clay soils helps their friability. But others warn that it will turn the clay soil into "concrete". Do you have any experience with adding sand?

The it will turn into concrete answer was the most correct one. Adding enough sand to change the structure is not practial due to the cost and volumes needed.