a raised-bed garden survives ‘killer compost’
‘WE ALL MAKE MISTAKES,’ public-TV host Joe Lamp’l of “Growing a Greener World” said when we chatted on my radio show. Oh, isn’t that the truth. Thankfully the misstep Joe revealed—how he fell prey to “killer compost” that contained persistent herbicides—was offset by a look at the most enviable of vegetable-garden designs. How to build the ultimate raised-bed garden (wait until you see Joe’s new layout!) and how to avoid inadvertently bringing in compost or compost ingredients that can do more harm than good. A hint: Animal manures can be tricky business.
joe lamp’l’s new garden plan
IT WAS TIME for “Growing a Greener World” to have a home “set” for some of its episodes, and Joe’s Atlanta farm was the perfect site. A total of 16 big raised beds—most of them 4 feet by 12 feet by 18 inches high, arranged in an area that’s 74 by 40—were fashioned of untreated cedar 6-by-6’s (photo up top). Paths of 4 feet were left between most beds (with a bit more clearance between the outer beds and the perimeter deer fence). So far, so good.
Tubing for a drip-irrigation system was installed before the beds were filled with 80 percent soil and 20 percent compost. And that’s when things took a bit of a wrong turn, at least temporarily.
the ‘killer compost’ phenomenon
AS WITH MOST garden bloopers—my many ones over the years included–trying to hurry things along caused this one, Joe says.
In his haste to get his new garden going in the spring, he eyed “the massive manure pile” contributed to by his horses, goats and chickens (that’s Joe with one of them, above). What he saw was a source of potential soil amendment—seemingly perfect material to mix with the carefully selected topsoil he’d be bringing in to fill most of each of those new beds.
Except for one thing—one thing he knew about, but pushed out of his mind.
“I’m aware of the potential hazards of using manure to amend garden soil,” he wrote in a recent story about “killer compost” (read it at this link—a real eye-opener). “I had been warning people as I speak around the country about this possibility,” says Joe, a frequent lecturer and writer, in addition to his TV role.
“Some herbicides used to control weeds in farm fields persist for a very long time.” Even worse, they don’t readily break down, even as composted manure. But, he says: “I talked myself into it—and into the garden beds it went.”
After incorporating the composted manure, Joe planted tomatoes and other vegetables. Pretty quickly, the plants didn’t look right: cupping of their leaves, and what he describes as “no apical dominance” (no clear lead growing point moving in the right upward direction, and the side shoots trying to take over).
He knew right away what had happened: Persistent herbicides on the fodder he’d fed his animals had made it through the compost process. He quickly confirmed with his hay supplier, who like other farmers had indeed used the chemicals to rid his fields of broadleaf weeds.
The manufacturers formulated these chemicals to last a long time, to offer farmers multiple seasons of protection against the broadleaf weeds.
“The composting process isn’t going to break it down,” says Joe, who adds: “The process takes from months to several years,” and is probably slower in the compost heap, an anaerobic environment. Yikes.
avoiding ‘killer compost’
KILLER COMPOST resulting from persistent herbicides is not a new phenomenon. The United States Composting Council says:
“We are specifically concerned with the relatively new class of herbicides called ‘pyridine-carboxylic acids’. They are typically designed for use in hayfields, horse pastures, golf courses, right-of-ways, and lawns to kill off unwanted weeds and to remain effective for several months to years. These herbicides do not impact grasses.
“There are a number of compounds that fall into the category of persistent herbicides. The most prevalent are Clopyralid (Dow Agrosciences), Aminopyralid (Dow Agrosciences, 2005), Aminocyclopyrachlor (DuPont, 2010), and Picloram (Dow Agrosciences). Less prevalent compounds in the same class include fluroxypyr, dopyralid, and triclopyr. Many of these compounds appear on labels in slightly different variations making identification by the untrained applicator or a testing lab difficult.”
Joe’s hay source had used Grazon, specifically, a trade name for a product containing Picloram.
joe’s plan to remediate his soil
JOE LAMP’L began right away to try to undo the lingering effects of the herbicides. Everyone said to remove all the soil, but that seemed a heroic task—financially and labor-wise.
He instead turned the soil (to expose the remaining compounds to sunlight and more oxygen, to help speed the process of decomposition). He planted cover crops, and though conventional wisdom about this says you need to pull them (because they would have absorbed some of the residue), he’s turning his “green manure” in to add bulk and hopefully offset the residues.
He is already seeing improvement: later crops did much better.
His best advice, though: Take a moment! Ask before you bring in any raw materials that may have been sprayed with persistent herbicides–manures, hay bales, bagged grass clippings from uncertain sources. Prevention is easier than the long process of remediation. More help:
- Read Joe Lamp’s full report on his “killer compost” experience.
- Read more about persistent herbicides on the Composting Council website.
- Learn to make compost in this “Growing a Greener World” episode.
- Watch the episode about how the team built Joe’s amazing new raised-bed vegetable garden.
joe lamp’l visits my garden: watch us!
JACK AND I AND OUR GARDEN were the subject of an episode of the “Growing a Greener World” public-television program. I hope you will watch–and share the link after you do. Watch Joe’s visit to our place now. Read his behind-the-scenes account of our two days together.
prefer the podcast version of the show?
MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its seventh year in March 2016. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
(All photos courtesy of Growing a Greener World television.)