Make your own organic mulch
By Barbara Damrosch
We live in a world of phobias, but here's a new one: fear of mulch. And there's some basis for it.
As reported in this paper July 11 ("Bitter Harvest in Sperryville"), a Virginia farm couple, Rachel Bynum and Eric Plaksin, lost a good deal of their year's harvest by mulching with hay they'd bought from a local farmer. After seeing distorted growth on a number of crops, they learned that the farmer had used an herbicide containing picloram.
Unlike herbicides such as 2,4-D that biodegrade quickly, picloram and the closely related clopyralid can persist in the soil for several years. Called growth regulator herbicides, these also persist in the manure of horses that eat the hay and in the vegetables you grow if you mulch or fertilize with hay or manure that contain them.
Writing in the current issue of Growing for Market, Bynum and Plaksin advise readers to "question any source of hay, manure or compost." I'd add that if you can't be sure it's pure, grow your own. The safest, most wholesome source of food and the materials with which it's grown is the closed loop of your own garden.
Mulch is a gardener's version of organic litter on the forest floor, a splendid ally that prevents erosion, keeps the soil moist and friable, calls earthworms to action, buffers both heat and cold, suppresses weeds and adds fertility to the soil as it breaks down. A mulch applied this fall will help protect your soil over the winter. Since the persistent herbicides occasionally found in mulch are harmful even in amounts too low to show up in testing, it's wise to ask the grower whether herbicides were used when you buy mulch hay.
Grass clippings that are yours for the taking can also contain herbicide residues. Mulch made from chipped-up wood can contain arsenic if pressure-treated wood has made its way into the mix. Best to provide your own.
You might not have room for a hayfield if your back 40 is a 40-foot veggie patch, but you can create mulch from autumn leaves by running your lawn mower over them. Your yard's grass clippings, pine needles and evergreen boughs are all good homegrown mulches -- even piles of weeds can be used if they're cut before they go to seed.
You could plant a winter cover crop such as winter rye or hairy vetch in your vegetable garden to protect the soil just as a winter mulch would, and there's time for it to make good growth if you sow it now. In spring, the plants can be turned under to add nutrients and organic matter to the soil, or cut and added to the compost bin. Or cut and stockpiled to use as a handy source of -- mulch!
Article copyright of Barbara Damrosch. Reprinted with permission.
Creative Commons photo credit: Nathan Y
