Grow your own soil conditioner. That's the idea of "green manure."
Unless your green-manure crop is a legume--a member of the pea or bean family--it will not add nutrients to the soil. (Legumes pull nitrogen from the air and "fix" it on their roots, leaving a dose of nitrogen in the soil). But it temporarily raises the soil's humus content, improves workability, and helps prevent nutrients from leaching and soil drom compacting during winter rains. Unlike animal manure, green manure doesn't contain salts that burn plants. It won't deplete soil nutrients unless you remove its foliage for compost--even then, depletion is slight.
Plant seeds of cool-season green manures now through mid-October west of the Cascades, late September into November in mild-winter California and the desert. Gardeners in cold-winter areas need to wait until spring. Planting green manure
Some legumes to grow for green manure, and approximate seeding rates for a 10- by 10-foot bed, are broad beans (fava, horse, bell, or Windsor beans), vetch, and peas (1/4 lb.); alfalfa and clover (1/4 to 1/2 lb.). Two nonleguminous plants you can use are annual rye (1/2 lb. per 10-foot-square plot) and kale (1/4 lb.).
To help legumes deposit more nitrogen in the soil, treat seeds with legume inoculant before planting.
Prepare a smooth bed, then broadcast seed; if your soil is low in nutrients, you might also broadcast a complete fertilizer. Using a rake, cover small seeds such as clover or rye with about 1/2 inch of soil; cover broad beans with 1 inch of soil. Water the bed well to firm soil over seeds and aid germination, and keep it moist until winter rains take over.
The crop should have time to establish itself before cold weather sets in. Plants appear to stop growing in winter, but the first warm days of spring boost growth. Three ways to harvest green manure
Plow it under. If your main objective is to add humans to the soil, till under the entire planting, preferably with a spade or reartined rotary tiller while plants are succulent and still easy to chop (before legumes start flowing or annual rye seedhead stalks lengthen). If you are going to spade in the crop by hand, or if growth is thick, mwo or scythe it first.
The bacteria involved in decomposing green manure temporarily rob soil of nitrogen, so if you've used a nonleguminous crop, wait a few weeks before planting or apply a nitrogen fertilizer.
Shear the crop. Cut green manure for compost or mulch, leaving only an easily tilled stubble to be worked into the soil. There is little nitrogen tie-up, so you can start spring planting right away. Or pull out the plants by hand; this will also give the bed a light cultivation.
Harvest edible parts first. If you plant peas or broad or bell beans, you can harvest some before tilling, though the plants, left past their prime of nitrogen fixation, may be wiry and hard to chop. (Note: some people of Mediterranean ancestry are extremely allergic to broad beans.) Brittle, succulent plants like kale can be more easily turned under.
For a no-work green manure, you can allow the usual winter weeds to grow, tilling them under before they go to seed. But planting a green manure can help control those weeds, important if you are breaking ground in a new plot (annual ryegrass, which produces a lot of foliage in a short time, is a good choice for this).
Check nurseries and feed stores for availability of cool-season seeds in the bulk. You can also order most of the green manures mentioned here--and a legume inoculant as well--by mail from Lagomarsino Seeds, 5675-A Power Inn rd., Sacramento 94824 (ask for free cover crop price list; Lockhart Seeds, Box 1361, Stockton, Calif. 95201 (catalog $1; refundable); or Territorial Seed Company, Box 27, Lorane, Ore. 97451 (free catalog).
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|Date:||Sep 1, 1984|
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