What is a good plan to remove and replace the poor soil on our residential lot?

Asked June 17, 2019, 6:43 PM EDT

Our lot in Portland is very rocky and very dense. Even with tilling and amendments it does not support plants well.

We intend to remove the top 12 inches of existing soil, and replace it with new soil optimized for ornamentals and edibles (many native species).

With limits on time and money we are thinking maybe:

1) Remove sod and yard debris
2) Remove 12 inches of existing soil
3) "Install" and grade 12 inches of new, improved soil

1) Plant freeze-hardy Cover Crops (to prevent erosion and prep soil for spring)

1) Monitor & maintain cover crops

1) Address winter cover crops
2) Prepare soil
3) Plant edibles and ornamentals (lawns will not - ever - be part of the landscape)

SUMMER 2020 and later
1) Plant edibles and ornamentals
2) Mulch, etc.
3) Maintain plantings and soil

Is ours a good timeline for the project? Are there other steps we are not considering? Thank You!

Multnomah County Oregon

1 Response

Removing existing soil is not advised, unless it is contaminated. Bringing in non-native soil has the disadvantage of likely creating a perched water table. Water doesn't move well between soils of varying textures, in simple terms. Soil structure is also a concern.
There are ways to care for the soil which will improve it for planting over time. Consider arborist wood chips; this WSU publication gives details: http://cru.cahe.wsu.edu/CEPublications/FS160E/FS160E.pdf?fbclid=IwAR2Ay04BFhPGWVHCy3_8PVZhzdIw0N8nQV...
For intensive gardening of edibles, consider constructing raised beds. Here is an OSU Extension publication: https://catalog.extension.oregonstate.edu/fs270
Your questions are hard to answer all in one response, and additional questions/ideas are welcome. One issue is what type of soil you have, understanding the soil where your home is. Perhaps you can find it on the soil map? https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm
Also, soil testing through a lab (we recommend A&L agriculture labs in the Portland Area) can determine where you are starting from with your land.
What general neighborhood are you in? (don't provide address on this public forum)