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As most readers of this site will recognise, nature always works to protect the soil from from wind and water erosion — by covering it with living foliage. In doing so, the cycle of life and death continues, increasing the soil’s fertility over time. Alas, many ‘modern’ gardeners have allowed themselves to become indoctrinated into trying to maintain a ‘tidy’, foliage-free garden bed — they will not rest until they’ve removed every green plant other than their own fruit and veg — but this simply begins a never-ending battle with ‘weeds’, that takes a lot of unnecessary effort, and ensures the soil and soil-life steadily gets depleted of that all-important organic matter and humus content. For many people, this impossible battle ends with chemical warfare…. Striving for a conventional ‘aesthetic’, they are, quite literally, losing the plot.
In its bid to cover up your soil, nature will use whatever resources it has at hand to do so — filling empty spaces from roots and seeds presently found in your soil. Some of these hardy pioneers, however, have characteristics that aren’t the most congenial to your particular purposes. Some are invasive, choking out the plants you really want, and some are just plain prickly! Over time, these plants normally bring a lot of benefit, but if we put a little design into this aspect, we can help ensure the empty spaces in our gardens and farms accommodate just the plants we want – those that serve multiple functions, and which are easier to manage and which work to the benefit of our edibles, rather than out-competing them. By choosing the right combinations, we can have the best of both worlds — a well-covered (protected) soil, plus aspects such as nitrogen fixation, soil aeration, mineral accumulation, large increases in biomass for increased humus accumulation, and more — as well as providing for a beautiful aesthetic!
A cover crop mix of cow pea, vetch, wheat and oats, under a fruiting apple tree
Photo © Craig Mackintosh
One of our forum members shared the chart at top, courtesy of groworganic.com, which I thought well worth putting here on our main page. Cover crops (otherwise known as ‘green manures’), are an important facet of any garden, market garden, or farming system. Getting to know the characteristics of the cover crops suitable for your area is time well spent.
The key ‘features’ you will want to look for when choosing a cover crop mix will somewhat depend on the type of soil you have, and, of course, its level of fertility. For example, if you have a heavy (high in clay content) soil, there is a high risk of compaction, which can create a waterlogged and anaerobic state that will stunt your plants and make them susceptible to disease. Whether you break up the soil with double-digging or not, such soils would benefit from a cover crop with strong and deep root systems that can try to penetrate any hard pans below the soil surface. A soil composition that’s high in sand would benefit from a cover crop mix that provides copious amounts of biomass, helping to increase the organic matter content that will help hold moisture in a way that sandy soils cannot. If your soil is generally depleted, you’ll want to major in nitrogen-fixing plants (most of the legumes fit into this category — like peas, beans, lentils, clovers, etc.), as well as those high in carbon (like rye, oats, wheat, barley, and so on). As you can see, many cover crops can be edible too!
Other benefits of having a diverse mix of cover crops, beyond soil composition and structure, are in providing habitat for beneficial, predatory insects and providing a greater diversity of flowers that improve the health of your local pollinator populations, and also serve as great pest distractors (although often you may want to cut the cover crop just above the soil surface just after flowering, to ensure the plants do not re-seed, if that is something you wish to avoid — but do leave the root systems in the ground where possible, as they will become soil food and ultimately leave aeration channels, and happier micro-organisms, behind!)
If you’re at a loss in which plants to use for your particular soil and circumstances, you might want to take one of our upcoming Sustainable Soils Management Courses with Paul Taylor. Getting to grips with how your soil and soil life functions enables you to be more creative and successful in implementing strategies that work towards abundance (see our course listings for next dates).
Anyway, check out the chart, and do let us know about your own cover crop resources and/or adventures — either by way of comment below, or as a separate article you can send through to me for publishing: editor (at) permaculturenews.org