[USCC] Revegetation of gravel pit soil

[Rufus Chaney]

Dear Perry and USCC folks:

I think the use of compost to revegetate a gravel pit is a wise choice, and less complicated that you think.

One has to first consider the nature of the soil before treatment. Some gravel pits are so acidic that plants are limited by aluminum toxicity and phosphate deficiency, besides the lack of soluble nutrients like N. One also needs to consider the likelihood of drought at the site since that will affect the rate of compost to be applied and even the choice of revegetation species.

For most gravel mine sites, acidic soils limit plant growth, along with nutrient deficiency, and leachability of inorganic chemical fertilizers. By including limestone enough to raise soil pH to say 6.5, plus application of 25 T/A of compost, one should be able to revegetate either gravel mines or coal mines where there were no metal toxicity problems except Al and Mn (the natural toxicity factors in acidic soils).
I would get advice from NRCS regarding revegetation plant species for the area involved. The site could be the bottom of the pit and clayey, or gravelly. So the droughtiness of the soil needs to be considered. A legume should be included in the revegetation mix.

With mature composts, the compost will provide N for plant growth. One trick to favor legumes was identified in a 1970s trial in Rhode Island. In that case they did not have a screen to remove the wood chips bulking agent, so the C:N ratio of the composted biosolids was very unfavorable for grasses. Of the seed mixture, only the legume survived; so they got a pure stand of alfalfa, something that was hard to do in those days with herbicides.

So, treat the site like any other infertile soil. Get soil analyses. Apply enough limestone to attain pH about 6-6.5 using dolomitic limestone to avoid future Mg deficiency. Incorporate 25 dry T/A of compost into the surface 6-8 inches with tillage equipment. Seed an appropriate mix for revegetation of roadside soils in your location. Stand back and watch the vegetation become established.

For metal toxic mine and smelter sites such as Sally Brown, Chuck Henry, Harry Compton and I have revegetated in the last 8 years, one has to apply more limestone to make the site calcareous, make sure the liming does not induce Mn deficiency, and apply enough compost to make sure the site will remain non-phytotoxic; commonly 100 T/A of P-rich compost or biosolids or manure amendment. by incorporating enough carbon with a N-rich biosolids or manure, one can immobilize the excess applied N rather than promote leaching. For the 25 T/A noted above for the gravel mine site, using compost with slow release N, one is still below the application which will cause concern about N leaching. In addition, compost is freed of pathogens from manure or biosolids, so it is safe for gravelly soils where a Class B biosolids would not be recommended.

Regards,

Rufus Chaney
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Date:	Mon, 11 Dec 2006 17:41:11 -0600
From:	"Perry Lindquist" <plindquist at waukeshacounty.gov>

To:	<compost at composter.com>

Subject:    Using Compost for Mine Reclamation

I am currently planning to use yard waste compost to reclaim a gravel pit.  I was wondering if anyone else had done this before and had some tips on things like:

1. Thickness/depth of compost to apply.
2. Subsoil application recommendations (for root zone water holding).
3. Application process (for non-screened compost).
4. Possible mixing with submaterials (sand & gravel).
5. Seeding recommendations for Wisconsin climate (cover crop and final).
6. Erosion control measures during stabilization (need for mulch, erosion netting or polymer).
7. Application to the bottom of a storm water infiltration basin that is seasonally wet. 
8.  Any other recommendations.

Any advice would be appreciated.  I have 20 years experience in erosion control, but this is a new thing for me.

Perry Lindquist
Manager, Land Resources Division
Waukesha County Dept. of Parks & Land Use
1320 Pewaukee Road - Room 260
Waukesha, WI   53188
Phone:  262-548-7867
FAX: 262-896-8298
e-mail: plindquist at waukeshacounty.gov
web: www.waukeshacounty.gov/landandparks