helping "fill" to become soil #264975 - Ask Extension


helping "fill" to become soil #264975

Asked July 26, 2015, 2:47 PM EDT

I tried to add a pdf specific from your area re this question.  If you can contact me at, I will send that on to you.

A lot of fill was spread around in the process of building my place: yellow, pebbly & not much else; very hard to dig a hole in. I've been happy to see ANYthing at all growing, any kind of a weed. There was a thin layer of topsoil, grass seed and hay spread out 5 years ago. The undisturbed soil of the wooded area is gorgeous, deep, rich soft... I'd like to know what I can do to build up the soil of the "fill" areas. Not so interested in gardening or landscaping per se... except as it would help the poor soil. There are some steep banks and some level areas; partial daylight; and I do cut it back in the spring with a string trimmer. My composting efforts are not enough - I live alone.  Can I plant something to help, & if so: what and when and how?  Other suggestions?  How to increase the volume of compost? Anything else?

Clatsop County Oregon

Expert Response

 Here is more info that one of our MGs has sent me to forward on to you. And here is the link for soil testing labs in the NW:

If the client would like to use their  indigenous soils so as to control unknown weed seeds and soil born diseases from purchased soils,  they could use the soil from their forest. We utilized the Forest Humus from our forested property and moved it into the disturbed areas that had no Top Soil and Hard-Pan dirt filled with rocks.

You did not mention how large an area you needed to amend , so I recommend dividing up your property into Zones based on your priority of what should be amended first, as this can make this large task more manageable.  Many native plants will move with the Forest Soil and set up a naturalized landscape such as Ferns, Bleeding hearts, Oxalis, Iris etc… Soon they reseed and with transferring your own soil you can get “free” plants already acclimatized to your growing region. There are many other plants that can be used if you chose to control the appearance of your grounds/landscape.

Knowing the status of your soil’s nutrients is a good place to start as this information can tell you what plants will be best supported by your soils nutrients and will offer suggestions as to what the soil is lacking that you will need to replace in order to have optimal results for plant growth.

Oregon Testing Labs: ( they can tell you what they need to test your soil, water, prices,  etc.)

A&L Western Portland Oregon 503-968-9225

Analytical La Eugene Oregon 800-262-5973

Pacific Analytical Lab Corvallis Oregon 541-753-4946

There are many Labs, these are just a few suggestions you might try.

Good Luck with your project!


Master Gardner Apprentice

Re: improving soil quality at recent construction site

·       Read the pdf file entitled Improving Garden Soils with Organic Matter (see link above) and the Columbia River Estuary Task Force study Entitled Erosion Control in Clatsop County, which addresses issues specific to building sites. (attached)

·       Divide the targeted area into “zones” and identify the light and slope conditions and whether deer are an issue

·       Depending upon your budget, either harvest soil from your forest area or buy top soil/compost (in bags or truckload)

·       Buy enough to put down a layer of 3-4 inches (length x width x depth = cubic feet)

·       Perform a soil test

(Soil test link)

·       Based on soil test add organic material amendments (commercial compost and manure) and possibly certain commercial organic fertilizers (read the labels carefully and follow the directions)

·       We recommend adding 1-2 inches of compost annually (Example: 1 cy covers 300 sf inch deep)

For slopes erosion control is important, so, planting, applying mulch and possibly terracing will be important

Planting suggestions:

Clatsop County is in planting zones 7b, , 8a, 8b, 9a.

·       Planting cover crops is an organic approach to improving soil. Plant in spring and turn under in the fall. This will serve to improve both the soil texture and the nutrients. Examples of cover crops recommended for Oregon include: Buckwheat, Common vitch, Crimson clover, Fava bean. Choose the crop that matches your light conditions (shade, part sun, full sun etc)

·       Planting for erosion control can include using ground covers. Examples of shade loving ground covers include bishops weed, yellow flowering lamium (careful can be invasive), golden moneywort, lily of the valley, bunchberry, vinca (careful can be invasive), wild ginger and sedum. For sunnier conditions consider the ice plant, ajuga, blue fescue grasses

·       For sunny areas considering re-seeding annuals such as California poppies, forget me nots, African daisies or self seeding perennials such as Echinacea

Our MG will add a personal note to this that I will send along later.

Scott Thiemann Replied July 29, 2015, 4:09 PM EDT

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