COVER CROPS SEEM TO BE FOREIGN TERRITORY to many home gardeners. It certainly isn’t because we aren’t in favor of the benefits they provide to the soil. Who isn’t behind a plan to increase soil fertility, add soil organic matter and make better soil structure while reducing soil erosion and nipping weed problems? I believe that gardeners just aren’t familiar with cover crops. One way to get schooled is to visit the Master Gardener Demonstration Garden, located at the Robert C. Parker School in North Greenbush. Nancy Scott and her master gardener friends have a great display of field peas, buckwheat, red clover, daikon radish, fava beans, oats and green beans growing right now! You are welcome to stop by during daylight hours.
Simply stated, cover crops cover the soil between harvestable crops. As they grow, they trap nutrients and break up soil compaction, and when they are mowed or plowed under they add organic matter and nutrients. Increasing the amount of organic matter in the soil by just 1% will make the soil hold an extra 27,000 gallons of water when it rains, thereby reducing runoff into rivers. More carbon in the soil also increases the fungi, bacteria and other wee beasties there, which in turn improves the soil “glue” and allows water to infiltrate more effectively. Plowing, rototilling or turning over the soil (all forms of tillage) reduces soil organic matter, releases nitrogen and increases weeds, problems which can be stemmed with cover crops. Eliminating or minimizing tillage and maximizing plant cover year-round protects the soil. During the times of the year when a crop isn’t being grown, the soil should therefore be swathed in a cover crop. Although these concepts are aimed at larger-scale farming, they apply just as well to our vegetable gardens, too.
A variety of plants are used as cover crops. Some are grasses, including rye, wheat, oats, and Sudangrass. They grow quickly and are good at trapping nutrients and suppressing weeds in the next crop. Others are legumes, such as cowpeas, vetches and clovers, famous for their ability to take nitrogen from the air and put it into the soil. Sometimes grasses and legumes are mixed, so that the nitrogen captured by the legume can be further sequestered by the grass. Two of the most interesting cover crop plants to me are the Daikon-type radish and buckwheat. The radishes quickly grow huge root systems, busting through tough soils, then die over winter, leaving improved water infiltration, surface drainage, and soil warming in their wake. Buckwheat is not a grass at all but a broadleaved plant which grows fast, loosening the soil and choking out weeds. It is normally mowed before it fully flowers, but anyone concerned about pollinators will let it go, since it is a favorite of honeybees and other beneficials.
Fitting cover crops into a vegetable garden plan is tricky, and gardeners may be reluctant to fork over usable space. Yet the many positives might just reap big rewards for a gardener willing to experiment.