Beware of bringing outside inputs into your garden! I began to hear about problems with persistent herbicides in compost that were causing crop damages when gardeners applied it to their gardens in 2001. It used to be that good organic gardeners gleaned compost materials from everywhere they could. They took in leaves and grass clippings from their neighbors and gladly hauled stable bedding from wherever they could find it. Even if these materials had been produced by conventional methods, rather than organic ones, it was thought that whatever residual chemicals might be left would break down in the composting process. Not anymore.
There is a 21st century problem of herbicides that can survive the composting process and still be active enough to cause herbicide damage on your vegetables. These herbicides target broadleaf plants and are used to produce weed-free lawns and weed-free hay and grain. If you used grass clippings or hay and straw from treated areas as mulch, you could find yourself with herbicide damage to your garden. Furthermore, if an animal ate the hay from a treated field and the manure was composted, that compost would still contain the active herbicide.
The first chemical I heard about was clopyralid, marketed by Dow AgroSciences. By 2004, the label had been changed to try to keep the clippings from treated turf out of the compost stream. Until 2007 I was reading about places far from my home. Then the September 2007 issue of Growing for Market published the article Contaminated hay ruins crops. The folks at Waterpenny Farm in Sperryville, VA had experienced herbicide damage on their tomatoes and squash as a result of applying hay as mulch. They had bought second quality hay, as usual, from a farmer they’d been dealing with for five years. Unfortunately, that farmer had begun using an herbicide containing picloram on the fields he cut. The herbicide salesman did the application and the farmer never saw the label, which stated not to use the hay from a treated field as mulch. At that time, September 2007, we were deep into working on our video Cover Crops and Compost Crops IN Your Garden. I had long since stopped using outside sources for compost and mulch materials as I concentrated on GROW BIOINTENSIVE methods.
If I did not already have that knowledge of how to use cover crops, I would have felt completely helpless. I was very sad to learn what happened at Waterpenny, knowing it would also be happening to countless others. On the other hand, our new video would show people how to raise their own compost and mulch materials as part of building their soil fertility. I was happy to be able to offer a solution.
For some updated research for this post, I headed to the library at the Western Campus of J. Sargeant Reynolds Community College where I used to teach. That library has the best selection of sustainable ag books I have ever seen. It also has BioCycle magazine. Sure enough, the June 2011 issue of BioCycle had the article Dupont Label Says “Do Not Compost” Grass Clippings by Dan Sullivan. It seems that this problem is never-ending. DuPont now has the herbicide aminocyclopyrachlor which has been marketed as Imprelis to the landscape industry–people who need a pesticide license to apply it. However, Scotts is going to be adding it to a product for homeowners– people who don’t have a pesticide applicator license. Watch for it in some of the Scotts Miracle-Gro weed control products in a garden center or big box store near you! Aminocyclopyrachlor will replace 2,4-D and atrazine in these products. Just two weeks ago, Barbara Pleasant wrote about aminocyclopyrachlor for Mother Earth News at http://www.motherearthnews.com/grow-it/imprelis-killer-compost-zb0z11zrog.aspx, including problems of Imprelis with trees and shrubs.
These companies know of the damage that can occur when these chemicals persist through composting and end up in your garden. They feel they are doing their part to keep them out of your gardens by including on the label instructions to not use what is taken off the fields or landscapes in compost or as mulch. In the real world, however, these things DO end up as compost or mulch. To protect yourself you would have to be able to go to the farmer and ask what has been applied to the field and search the label yourself. The feed store that you get your hay and straw from may have run out of their local supply and brought some in from far away. The place you got that truckload of compost from may have many input sources. Good luck! If you already have a problem with contaminated soil, learn all you can. You will have to play a waiting game for a few years for the herbicide to no longer be effective, but you can grow grass there. Barbara Pleasant reports a way to test for these chemicals by soaking the materials and using the water on pots of beans at http://www.motherearthnews.com/ask-our-experts/simple-compost-test.aspx. For more information on this issue, google “killer compost”.
You could forget about those other sources and only use what you grow yourself. Besides, bringing materials from outside your boundaries depletes the soil where they are grown. What is going to feed back that area? We have to look at the whole picture–the complete cycle.
My video Cover Crops and Compost Crops IN Your Garden takes you from March through November in my garden and shows you how to manage those crops using only hand tools. My video Develop a Sustainable Vegetable Garden Plan shows you how to plan those crops into your rotation. Choosing the right crops and planting and harvesting them at the right time takes some practice. My blog will give you help along the way with posts such as Cutting a Rye Cover Crop at Pollen Shed and Grains in Your Garden.
It appears there will be persistent herbicides with us for quite awhile. Rather than try to learn the chemical names and the products they are used in, it is best to avoid any herbicide use altogether. Think of your property as one living organism. Whatever is done to one bit of it affects the rest. Learn to manage your soil fertility with cover crops and you and your garden will be much healthier. Happy cover cropping!