Now that you are all aware of the dangers of bringing outside inputs into your garden from my last post, you are probably wondering just how you go about growing enough cover crops to make all your own compost to feed back the soil. Cover crops are crops grown specifically to feed the soil, although some also produce food for people in the process. According to GROW BIOINTENSIVE (GB) methods, you would have to plan to have these crops in 60% of the garden for the year. Keep in mind, however, that I’m talking about the whole year. Many people only grow things in their garden from spring till fall and at the end of the growing season they just leave things as they are until the spring clean-up. I’m talking about keeping your soil active and having something in there for all twelve months. For those of you who want a biblical fallow year every seventh, that is easily arranged with this system.
To plan for this 60%, you would first need to know the area of your actual planting space. If it is divided into growing beds of equal size then you already know how many beds you have. Each bed has twelve Bed Crop Months (BCM)–twelve months that a crop could be grown there. If the space in your garden is divided into planting areas of different sizes, you would need to work through this exercise using the number of square feet being planted, rather than the number of beds.
The cover crops you would be growing might include cereal rye, wheat, clovers of any kind, winter peas, spring field peas, buckwheat, sunflowers, and Jerusalem artichokes. Some of these crops might be cut early to lay down as mulch and information about that is in my videos and my post on 5/17/11. Some crops such as rye and wheat are grown for their straw for compost and food for the table. Corn, sunflowers, and Jerusalem artichokes also provide much needed carbon for the compost pile with their stalks. The clovers and peas would provide nitrogen for the compost with their biomass. In GB terms, they are the immature crops and the straw and stalk producing crops are the mature crops. I have a worksheet that will help you figure how to get that 60% of soil building crops. You can access the worksheet at BCM worksheet and it is available on the resource page of my website. For those of you with dial-up internet, it is a form with four columns labeled: Bed #, Crops, 60% Crop BCM, and 40% Crop BCM. To help you with this project, you should have a garden map with every bed filled in with what’s growing there for the entire year and the dates those crops occupy each space. Make sure each bed is labeled with a number.
Determine the total Bed Crops Months (BCM) for your garden by multiplying the number of beds times twelve. 60% of that number would be the target for cover crop/compost crop BCM. Compost crops are cover crops grown specifically for the compost pile, but I’ll just refer to all these crops as cover crops.
Now, referring to your garden map, list all your crops on the worksheet beginning with everything that is in Bed #1, then Bed #2, etc. If it is a cover crop, including those grown for food such as small grains and corn, work out the equation (# of beds X # of months in the bed = BCM) in the 60% BCM column. If the crop is not a soil building one, work the equation (# of beds X # of months in the bed = BCM) in the 40% column. Total up the BCM in each the 60% column and the 40% column. If the whole bed is planted in the same thing, the # of beds in the equation would be one, of course. However, you might have several crops growing in the bed at the same time. In that case, the # would be the portion of the bed in that crop.
If you presently do not have your garden filled all twelve months of the year, it should be interesting to figure everything just the way you have it planted now. Divide each total by the total BCM for your garden to find the percentage of each. If your garden is not full for the year, combining the totals for the 60% and the 40% crops won’t add up to 100%. The percentage that it would take to reach 100 is your opportunity to fill it with cover crops. Then, with some adjusting with your present crops, you will probably discover that it’s not as hard as you thought to reach 60%. Remember, if your garden beds are different sizes, instead of BCM you would be working out your calculations using square feet rather than beds.
These crops are going to be feeding back the soil by their roots being left to decompose, by composting in place, and by being made into compost to be put back onto the beds. If you are short on cover crop BCM you might plant red clover (different from crimson clover) or alfalfa and have it grow in an area for two years, taking cuttings both years for compost material. If you really insist that fallow means nothing is cut, you could designate a bed in your rotation to hold your compost. It’s not technically part of your 60%, but it wouldn”t be growing anything else and it would accumulate nutrients by whatever leaches from the compost. The next year the compost rotates to the next bed.
An example of all this is a bed which has tomatoes in it from May through mid-October. The tomatoes, a 40% crop, would have 5.5 BCM, which is 45.8% of the 12 BCM for the year. If the other 6.5 months are filled with cover crops, that would be 54.2%, a little short of the target of 60%. That means that other beds in the garden need to make up for that. However, if you had corn in your rotation, with a cover crop before and after, the corn being a mature carbon crop for the compost, you would have 60% crops for all twelve BCM. My video Cover Crops and Compost Crops IN Your Garden shows you how to cut corn with a machete for the compost pile. If your garden consisted of only those two beds, it would have 24 BCM (2 beds x 12 BCM) with 77% of the garden in 60% crops for the year, leaving you with some leeway for a third bed.
For some of you, this is all way too much information at this point in your gardening journey. If so, that’s okay. At one time, it would have been overwhelming to me, too. Just know that the information is here when you need it. For those of you who have been waiting for just this kind of information, you may be interested in reading the GROW BIOINTENSIVE material published by Ecology Action. Booklet #32 GROW BIOINTENSIVE Composting and Growing Compost Materials, Booklet #31 Designing a GROW BIOINTENSIVE Sustainable Mini-farm, and Booklet #33 Grow Your Own Grains; Raising, Harvesting and Uses are all available through Bountiful Gardens. Growing cover crops on this scale will do wonderful things for your soil, not to mention the terrific compost you can make, right IN your garden.
Make your garden map and work through the worksheet. You will now know what possibilities await you for your garden planning. In my next post on 8/23/11, I’ll help you choose which cover crops to plant where. For now, as your crops begin to fade, or suddenly die as zucchini is prone to do, harvest them as compost material and toss some buckwheat in their place to keep the weeds away. It will do good things for your soil and provide important nectar for the bees with its flowers in about 30 days. That will give you time to decide exactly which cover crop will go there for the winter.
In the hustle and bustle of your summer, remember to take time to smell the flowers and to sit and listen to the sounds of nature around you. We can learn much from quieting ourselves and observing the gifts that are right in front of us every day.