I spoke with someone this week who wanted to know where to find the absolute BEST compost for her organic garden. She has a compost pile in her own yard, but it doesn't make enough for the whole garden. I suggested that she try Farmer D's compost, which - even though it is expensive - is locally available and an absolutely beautiful product. It is made partly with leftover produce from multiple Whole Foods stores.
However, she was concerned about pesticide residues, since not all of the produce at Whole Foods is organically grown. She also pointed out -- when I brought up mushroom compost as an alternative -- problems with the substrate that commercial mushrooms are grown on, which then is often made into (some pretty good) compost. Apparently, she had read that sometimes bits of particle board and other pressed wood products, some of which contain formaldehyde, are used as the growing medium.
Many of us are going to be a little less picky about the residues in the
compost, since most of the worst chemicals will have broken down into
components that (hopefully) are less of a problem, but my friend has
some issues with past chemical exposure that have made her
understandably wary of bringing any more potentially risky chemicals
into her environment.
After discussing and rejecting a couple of other possibilities, it became pretty clear to me that there is almost no way to obtain large quantities of completely non-contaminated, composted organic matter for use in the home garden.
The only good alternative I could think of was intensive use of cover crops to add the needed organic matter. For new ground that can be kept out of food-production for a full year, starting now with some kind of peas (it won't matter which kind), plowing those in then leaving them for a week or so to begin decomposition, followed by buckwheat in May that is plowed in after it has begun to flower, followed by another round of buckwheat or some cowpeas, followed by a winter cover of rye plus either hairy vetch or Austrian winter peas, would get the soil into pretty good shape. The cover crops would, of course, need to be amended following recommendations on soil test results, especially with regard to bringing our area's naturally low soil pH into a better range for the desired plants.
Most organic gardeners here in Cobb County need to incorporate cover crops in the rotation anyway, to keep the soil phosphorus levels in bounds, but to get a big slug of organic matter into the soil using cover crops alone will take some planning.