In my book, compost is the single best soil amendment you can add to your lawn and garden. Even better, you can make it for free. So not only is the price right, but as the person creating it, you know exactly what the ingredients are going in to make it.
But there’s a downside. Most of us only have the capacity to make a limited amount over a season or two. Even in my large garden where I’m adding inputs nearly every day, I never have as much as I need for everywhere I want to use it.
So what’s the solution? You could buy it by the bag. It’s a reasonable option but unless you only need a few bags, that can get pretty expensive quickly. The other option is to buy in bulk, which can provide a significant savings. In fact, one cubic yard (about half a pickup bed full) is equal to roughly 27 bags of compost. And of course, you could always buy enough to have it delivered. There’s never a shortage for the many uses of compost!
Either way, unlike the compost you make at home, how do you know what’s going into the compost you buy elsewhere? For me, that’s a real concern in my garden and landscape.
Fortunately, there is a solution, and it’s a good one.
The US Composting Council created a Seal of Testing Assurance Program (‘STA’) a while back to address these very concerns. Basically it’s a compost testing, labeling and information disclosure program designed to give consumers the information needed to compare compost products.
The program was also created to maximize the benefit from the use of compost as determined through a consensus of many of the leading compost research scientists in the United States.
The assessments include a pre-defined program of physical, chemical and biological tests that can be performed by a number of independent, certified labs across the country and in Canada.
Compost manufacturers apply to enroll in the program through the US Composting Council. If accepted, they’re required to regularly submit samples to an approved lab for testing their compost products.
Naturally, it’s in the best interest of the manufacturer to know what’s coming in from their feedstock, since detection of unacceptable material or levels can prevent the STA certification approval.
When a sample comes into the lab for testing, it’s analyzed for a number of properties including:
Soluble salts, pH, nutrients, organic matter, pathogens and trace metals. Two other important tests included in the STA Program are to assess compost stability (to know when the compost is finished, mature, and ready to use) and seedling growth comparisons (to know that the sample does not inhibit growth).
While these are all important factors in determining what goes into your garden soil, first and foremost, the compost must be safe to use.
Only when the compost sample passes these rigid criteria for acceptance can the product have the right to be called “Certified Compost” and use this STA – Certified Compost logo in their promotional materials.
So how do you find it? The US Composting Council has a Compost Locator Map on their website to make that job easy to find by the bag or bulk. Chances are, there’s a location near you. And if you care to see the details, STA compost manufacturers are required to have current analysis information wherever products are sold. Just ask for it.
Disclosure: At the time of this writing, I am the spokesperson for the US Composting Council (USCC). Although the thoughts and opinions in this post are indeed my own, the USCC who sponsored it compensated me in some way to write it. Rest assured that I only accept such offers when I genuinely believe in a product or service, use it personally, or believe it to be good information worth sharing with my audience.