Compost Safety and Leguminous Rhythms
It’s November in Indiana, and I’m raising little bean plants in my guest room. They’re not an early start for next spring’s garden, but a test of some new compost. Despite my best efforts, I couldn’t make enough compost this year to nourish the major garden expansion I’m working on, so I purchased a truckload of locally made compost from a nearby lawn and garden supply shop to supplement what I did make.
Other people’s compost is a little bit suspect these days due to the emergence of a new class of herbicides which persist in soil, in plant material, and in animal manure for up to five years after application. These herbicides are sometimes used on conventionally grown grain crops and grazing pastures, so they can wind up in your organic garden through compost, straw, hay, grass clippings, or manure.
Not only do I try to avoid ingesting herbicides as a personal health preference, and not only do I endeavor to manage my farm organically for myriad reasons, but the whole point of herbicides is to kill plants, so nobody wants them in their garden harming their flowers and veggies for the next several years.
Since these chemicals have such a long active life, sometimes persistent herbicides can contaminate a batch of compost by accident if somebody fed their horse something that once grew in a field that was once sprayed and then the manure from that horse is composted, or if contaminated straw or hay was added directly to the compost pile. It’s difficult if not impossible to verify all the inputs all the way to their origin if you’re a business or a municipality who takes in other people’s compostables and makes large quantities of black gold for a whole community. The best way I’ve found to make sure that not-homemade compost is safe is to test it before spreading it on the garden.
Ergo, I have six pots of Phaseolus vulgaris in my guest room right now, and we’re learning a lot about each other. Most interestingly, I learned that they “sleep” every night. They actually fold up their leaves into a relaxed-looking posture and spend the night that way before stretching out for the sun again the next morning. This botanical process is called nyctinasty. According to Wikipedia, “Nyctinastic movements are associated with diurnal light and temperature changes and controlled by the circadian clock.” Not all plants have nyctinastic movements, but some plants do, including beans. I plan to research more about nyctinasty, but I couldn’t wait to share these photos and observations with you all. See below for more info.
So far, all my beans look vigorous and healthy, and all signs point to safe, excellent compost. I’ll know for sure in another week, and then I can proceed with my garden expansion at full speed.
- More info about persistent herbicides in compost: Persistent Herbicides FAQ by Composting Council
- Full instructions for the compost test I am currently conducting: How to Test Compost for Herbicide Contamination by UC ANR