GREEN MANURES

Winter is here and the garden looks a little raunchy. Now is the time for gardeners to start dreaming about spring; more importantly, it is time for organic gardeners to start preparing for spring by planting a manure crop. There are two basic types of green manure plants: those that fix nitrogen to the soil and those that do not. Plants like mustard, ryegrass and buckwheat are sown in the fall and turned into the soil in the spring. The primary purpose of these cover crops is to enrich the soil by adding organic material to it. Cover crops are primarily used in large agricultural operations by farmers who have the tractors and plows necessary to manage crops of this type. For the home gardener, cover crops like ryegrass and buckwheat may be more trouble than they are worth, at least that has been my experience. The second type of green manure actually fixes nitrogen to the soil. These plants have bacteria that live in the tiny nodules of their roots that remove nitrogen from the air and add it to the soil. The nitrogen-fixers include alfalfa, red clover, lupin and fava beans. I consider alfalfa and clover to be weeds and would not plant them in my garden. On the other hand, I have found fava beans to be an ideal winter cover crop. Fava beans are easy to grow and, although not my favorite variety of bean, they are eatable. Plant the beans one inch deep and six inches apart in rows about 12 inches in width. Don't forget to soak the beans in water overnight before planting them. Be sure to turn the plants in, rather than pull them out, next spring since most of the nitrogen they add to the soil is attached to their roots. Finally, let a couple of rows mature and save the dried beans so that you do not have to buy them again next fall when you plant your next green manure crop. I also have a generous sprinkling of lupins throughout my organic garden; however, these plants are grown for their beauty rather than their nitrogen fixing capabilities and, in any case, are not a winter crop.