search
top

Sourcing compost

As an edible landscaper who encourages natural or organic gardening, Im concerned about the quality of dirt we import for clients to grow their food in.  This is a much more complex and challenging subject matter than it would seem, thanks in large part to industrial-chemical farming whose reach extends into our backyards and our dinner plates regularly, though we have no way of really tracking it.

(Let me just say, I have put off this blog post for several weeks now, attempting to find a way to present this without sounding as exasperated as i am…..  but here it is anyway…)

Its a very simple subject matter to most landscape supply companies.  Here is a typical conversation- I have had probably a dozen times- and again yesterday in Marietta:

Me: I see you are advertising organic compost.  Im looking high and low for some.  Please give me the specs!

Landscape Supply: Well, this is screened topsoil, meant for fescue.  This one is organic planting soil meant for flowers, and this one is blended topsoil for sod.

Me: Ok.  More info, please.  Can you tell me what’s in that organic planting soil?

LS: Composted chicken manure and other composted materials.

Me: where does the chicken manure come from and what are the other materials?

LS: Well…….  (awkward pause) we really dont know either.

Me:  Well, do you have some lab tests for me to review, as industrial chicken farming (where this was likely sourced) can result in compost with detectable arsenic?

LS:  Well, no.

Me: Heavy metals?

LS: Dont know.  I really cant tell you where it comes from or what’s in it, but it’s $30 a cubic yard.  Want some or not?

This may have been less of an issue when we were focused on growing landscapes simply for the appearance of green, but now that so many of us are learning the value and reward of putting our landscape resources to good use and growing delicious, edible landscapes, the complete lack of awareness about the soil we are importing is a bit disconcerting.

And further- even if they could tell me exactly where it came from, what the process was and that they tested for metals, we have no way of knowing what chemicals it might contain.  In a previous post on Containments in Urban Soil, I wrote about a grad student at Johns Hopkins (a leader in this research) reports there are too many possible chemicals to really test for, unless you know of a specific point source nearby.  He had some good suggestions for metals.

Duane Marcus at the Funny Farm nearby recently tipped me off to a growing national problem of compost laced with herbicides making its way into backyards gardens and vegetable crops being put to a “slow death” as a result.   Not to mention the health effects of those who are eating the produce.

I regularly recommend Farmer D’s biodynamic compost blend- of course we cant be sure of chemical containments, but I’ve checked and the metals are very low, nutrients and pH are on target. Plus, plants respond very well.  Of course there are people who understandably won’t or cannot afford its $100/cubic yard pricetag.

What then?  Another newer compost company who I’ve also screened for pH, nutrients and metals and those are fine, except a pile recently showed up on a job site stinking distinctly of—- garbage.  And we found quite a bit of garbage in it.  This is probably due to grocery store packaging.  When composting in that scale, I can imagine they dont have the labor to go through and pick out every piece of styrofoam that a grocery employee threw into the bin with the zucchini.

I live and work frequently in Dekalb county and find their bulk compost available per delivery from the landfill (comes from residential landscape waste- the brown bags of leaves at the curb).  Ive found this compost needs a year or two before it can be planted in, but seems t be good stuff.  I have not seen test results, but think it’s mostly safe from heavy metals as it’s considered Type A, does not contain human waste (MSW).

Another important piece to this puzzle is how do these soil containments translate from our edible landscape to our bodies? do they affect us?  We are pretty sure how heavy metals are detrimental, and arsenic….. another area that needs more research.

I dont have a solution yet, except to encourage people to make their own compost!  The best way to get the most out of your compost is make a biodynamic compost pile- see my post on the subject here. If you are in a highly urban area then an enclosed wormbin is an excellent choice.  Im planning to do a series of soil tests of Dekalb county compost to be more sure of this….. To be continued for sure

Leave a Reply

top