Feed the Soil

This year our cover crop is a blur of purple and white pea flowers. Every year we sow a “soil builder” blend of cover crop seed. The idea is to “make a deposit of seeds” which then germinate and “accrue interest,”  growing into a valuable crop of carbon and nutrients that can be “reinvested” by getting plowed under. There are grasses in the mix, like barley, oats, and rye. The grains germinate fast and first. And there are legumes in the mix; fava beans, vetch, and peas. The legumes sprout later than the grasses, and as the grasses grow taller the vining vetches and peas can lean on them in support. While the fava beans don’t need the grasses for support, they do benefit from the way the grasses act to break the winds that might beat them down.

The grasses in the cover crop mix do a lot to lock down the soil and keep it from eroding in the rain. The legumes capture lots of available atmospheric nitrogen for the soil. Together the grains and legumes that make up a well blended cover crop can grow a rich, green thatch of foliage, and when the farmer turns the cover crop under the farm “feeds the soil.” The cover crop captures carbon from the air and when  the farmer turns the cover crop under that carbon is put into the soil where it acts to make the earth more biologically active, with better water retention and  more friable texture. In many cases, a good, thick cover crop can also act to clean the soil of weeds. In our fields, for example, malva, or “pigweed” is a problem. The feral malva seeds in the field will germinate with the first rains, the same as the cover crop we’ve planted, but the cover crop will choke them out before they can flower and set more seed, so the field gets a little cleaner with every cover crop.

But just because we plant the same blend of seed every year doesn’t mean the crop comes out the same every year. We’ve had years with such cold weather that all the peas and favas were killed by frost and the cover crop was almost pure rye, because rye is tough in the face of cold weather. This year, Starr and I tossed out the cover crop seed by hand, counting on the dark clouds overhead to rain our seed into the newly turned soil. But after we planted our cover crop the clouds left without raining and a flock of birds came out of the sky and pecked up most of the grass seeds we’d just sown. The birds moved on when they’d mined out most of the oats and rye but they didn’t care for the peas, vetches or fava beans, so our cover crop is mostly made up of legumes. We didn’t have a “wet” winter, but we got rain enough to support a flourishing cover crop. There’s a sweet scent in the air from all the blossoms. I’ll almost be sad to turn this crop under.