Green manures, sometimes referred to as cover crops, are crops that are grown with the intention of tilling or plowing them back into the soil for increased garden fertility. They include legumes such as clover, alfalfa, beans, peas and vetch as well as grasses such as rye, winter wheat, oats and buckwheat. We’ve used just about every one of these green manures at one time or another during our 42 years of off-grid homesteading.
Benefits of Green Manures
Green manures improve soils by adding organic matter as well as nutrients and even help to control weeds. When growing, they prevent soil erosion from winds as well as heavy rains. When incorporated into the earth, all the various nutrients that went into growing the green manure are added back to the ground and all that organic matter helps improve soil structure, a plus if you have sandy or heavy clay soil.
All legume green manures add nitrogen to the soil. These plants “fix” nitrogen on their roots from the air into the soil, thus becoming a built-in source of nitrogen that once turned under is now available for the next crop. This is one way green manure increases garden fertility.
The grasses, or non-legumes, are a great way to build up lots of organic matter since they usually produce more lush growth as compared to legumes. Some are notably hardy and can be grown through the winter, especially in milder areas of the country. Winter wheat and winter rye are two examples that are good candidates for winter cover crops. When worked into the soil while still green, the grasses create humus and eventually contribute fertility to the soil.
Planting Green Manures
When deciding what green manure to plant keep in mind several factors. What is the time of year when you are planting? Heat loving legumes such as beans benefit from being planted in the spring or summer whereas cool weather grasses such as winter rye are best planted in the fall.
What is your goal? Do you want to add nitrogen to your soil? If so plant legumes. If you simply want to increase organic matter content, plant a non-legume. If you are unsure what is best, don’t despair. Plant a mix of both legumes and non-legumes. Just plant some kind of cover crop and work it in when the time comes. Any rooting and growth is going to benefit your soil once turned over. Your garden will benefit regardless.
Here in Nova Scotia, we are creating our third and final homestead – in other words the final frontier. When we arrived here 5 years ago, all our garden areas were forested or covered with scrubby growth of alder and brambles. Needless to say the soil was quite poor. It lacked all nutrients, was acidic and the structure was abysmal; a heavy, wet clay that was easily compacted into a hard concrete-like mass. To address this, we’ve embarked on a soil building campaign that has included cover crops/green manures.
Each summer, as soon as a vegetable crop is finished and its remnants have been relegated to the compost pile, we plant buckwheat in the open space. We continue this schedule until the fall, roughly early to mid September when we switch to planting winter rye. As more and more vegetables are harvested, more and more ground gets sown to rye. When the gray, overcast days of November roll around, yet the garden is still a sea of bright, emerald green due to rye that is several inches high, we are rewarded with a heartwarming sight.
Our method of planting any green manure is strictly manual. No machinery or mechanical devices are used. We broadcast the seed by hand with a sweeping motion of the arm back and forth while allowing the seeds to trickle through our fingers. Once the area is covered with seed, we take the back end of a rake and go over the soil surface. Some seeds are covered, some aren’t, some may be too deep but we always manage to get good growth coverage wherever we plant using this method.
We generally turn the buckwheat under just when it’s blooming. Because the buckwheat is grown in patches throughout the garden in the summer wherever space becomes available, we simply turn it under with a shovel as accessing all the small patches with our tiller would be impossible. The rye is worked in using our tiller during the spring tilling prior to planting . After using green manures for 2 years, we could see a difference in the soil structure as well as the vegetable yields.
If you are opposed to growing green manures in the hodge podge fashion we do, one option is to make them a part of your rotation plan. Each year, a portion of your garden is allocated to growing nothing but green manures that are turned under at the appropriate time. This means that a portion of the garden is unavailable for vegetable growth for the season. But the trade off is the following year, that area should produce bumper crops due to the positive attributes of green manures. We’ve never had a big enough garden space so that we could afford to have any of it completely unproductive for a season, hence our willy nilly approach to growing green manures.
Which ever approach you choose, you’ll not be sorry you’ve chosen to use green manures to increase garden fertility.
Until next time, keep the dream alive! We wish you a great day!
Ron and Johanna
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