Cover crops offer many benefits to soils and gardens. They protect soil from the compacting and dissolving force of the rain. They provide shelter for worms who might otherwise drown in our rain soaked soils. They supply home grown organic matter, which builds humus, improves soil tilth and texture, feeds worms and micro-organisms, and supports the soil nutrient cycle.
Cover crops also protect soil fertility levels by utilizing nutrients that could be leached into sub soils and aquifers and find their way, as pollutants, into our water ways. Soil nutrients bound in living plant material is not subject to leaching. In addition, by carefully selecting the cover crops, you can improve your soils carbon and nitrogen content.
Carbon is essential to the life of soil micro-organisms and the soil nutrient cycle. It is especially useful if you have noticed that plants in your garden tend to have weak stems and trail, sprawl, or lean when they should be upright. (Weak stems can be a sign of carbon impoverished soils.) Carbon is produced in abundance by the following easy to grow cover crops: agricultural mustard, flax, fodder radish, tyfon, winter oats, rice, rye, as well as winter triticale and wheat. As soon as your summer crops are through producing, you can cut them off at ground level and rake them into a compost pile (or turn them under) and broadcast your rows or beds with the carbon crops of your choice. (Cover crops should be sown thickly. You want the plants to inter-grow to protect the soil.) The carbon that these plants provide is extracted from the air, so you can congratulate yourself on doing something small to help with the greenhouse effect and global warming! Many of these plants will also produce edible greens or seeds, in addition to improving your soil.
Agricultural mustard, fodder radish, and tyfon can all be eaten in soups or sautéed with garlic and onions for an old fashioned dish known simply as “a mess of greens.” They are good sources of beta-carotene, folic acid, and calcium. (You can improve your own health while you improve the health of your soil!) Once these cover crops go to seed, if you let them grow that long, the seed can be threshed and used to grow spicy sprouts that will enliven your spring and summer salads. These same seeds can be used to flavor pickles, cracked to make a spicy seasoning for savory breads, and ground and mixed with vinegar to make dark flavorful mustards.
Flax, oats, rice, rye, triticale, and wheat seeds are also edible. They can be used whole, in mixed grain dishes, sprouted for salads or sandwiches, or ground and used in baked goods. If you want to try eating your grain, be sure to choose those that “resists lodging” if available, and definitely avoid those prone to lodging. (Lodging is a term used to refer to the plants dropping the grain.) Also look for varieties that are hull-less or easily threshed. Don’t expect to get a lot of grain from your garden, but it is a fun experiment to try which children, and it helps everyone understand how their food is produced. Dried grain seed heads are also fabulous for crafts. They don’t need to be hull-less or easily threshed for use in flower arrangements, wreathes, and so forth, so you can choose decorative colors or long awned grains if you like.
The other option in cover crops is to focus on nitrogen fixing plants. A variety of legumes are available that pull nitrogen right out of the air. If plants in this year’s garden grew slow, seemed smaller than normal, or if the green colors seemed faded out, nitrogen fixers might be just what you need to perk your soil back up. A number of types of clover, and vetch are available for cover crops. Low growing white and red clovers can be broadcast under summer crops now, or you can wait until the beds are cleared or turned and then broadcast the seeds. The Sweet Clovers are a nice option for cleared beds, as they also produce a lot of carbon and organic matter, and will reward you with sweet smelling flowers in late winter and early spring. As they are slow growing, it is a good idea to mix them with agricultural mustard or other clovers to best protect your soil from early rains.
If you want to grow a mix of carbon and nitrogen for your garden, add some Austrian field peas to your carbon crops when you sow the seed. Austrian field peas happily inter-grow with other plants. They produce small cheerful sweet pea type flowers and their seeds can be used in soups. Another choice, bell beans, are miniature fava beans that do well in winter. These beans do not need staking or trellising. They produce both nitrogen and carbon. And like other beans, the immature pods, as well as the mature beans are edible. To best protect your soil bell beans should be inter-grown with red or white clover.
Cover crops are pretty easy, you just choose your seeds, minimally prepare your ground, and broadcast the seed fairly thickly. You can cover the seed with a sifting of compost, leaf mould, or a purchased soil amendment. If this is not practical, and you have turned your summer crops under, you can rake the seed in. For a third option , you can simply cut or mow your summer rows, and wait for the next rain. Seed broadcast while it is raining are fairly safe from marauding birds. The action of the falling water settles the seed into crevices in the soils surface, and the moisture helps it germinate quickly. Then you just let nature take its course. (Cover crops can be cut or mown during the winter to keep their height down, if you choose. But it is not necessary.) Next spring you will have to decide if you are going to let your cover crops mature for their seed, or if you will cut or turn them under as soon as you are ready to plant your spring garden. That mostly depends on how much space you have. Either way, your winter cover crop will provide you with ample material for composting and mulching. Your soil and the creatures that live in it will thank you.
Check with your local farm supply or feed store for recommendations on the varieties best suited to your area. If you would like more information visit Bountiful Gardens On-Line: http://www.bountifulgardens.org or call (707) 59-6410 to request a catalog. They have seed for all the varieties mentioned in this article, and many other choices.
That’s all for now, but stay tuned, next time we will be getting ready to grow some of the yummy giant fava beans. Until them, you can probably find me out in the garden, Digging the Dirt.
Copyright 2006 Harvest McCampbell, from my column "Digging the Dirt," published in The Hoopa Valley People Newspaper, Oct 17, 2006. Posted here with permission. http://www.hoopa-nsn.gov/enterprises/newspaper.htm