Green Manure Crops
Another important contribution of green manure to an agricultural field is the nitrogen fixing ability and consequent nitrogen accumulation in the soil, particularly of those leguminous crops used. Depending on the species of cover crop grown, the amount of nitrogen released into the soil lies between 40 and 200 pounds per acre. With green manure use, the amount of nitrogen that is available to the succeeding crop is usually in the range of 40-60% of the total amount of nitrogen that is contained within the green manure crop.
| Average biomass yields and nitrogen yields of several legumes by crop: | Biomass tons acre−1 | N lbs acre−1 |
|---|---|---|
| Sweet clover | 1.75 | 120 |
| Berseem clover | 1.10 | 70 |
| Crimson clover | 1.40 | 100 |
| Hairy vetch | 1.75 | 110 |
- Winter cover crops such as oats or rye have long been used as green manures.
- Fava beans
- Mustard
- Clover
- Vetch (Vicia sativa)
- Buckwheat in temperate regions
- Lupin
- Fenugreek
- Sunn hemp, a tropical legume
- Alfalfa, which sends roots deep to bring nutrients to the surface.
- Velvet bean (Mucuna pruriens), common in the southern US during the early part of the 20th century, before being replaced by soybeans, popular today in most tropical countries, especially in Central America, where it is the main green manure used in slash/mulch farming practices
- Tyfon, a Brassica known for a strong tap root that breaks up heavy soils.
- Ferns of the genus Azolla have been used as a green manure in southeast Asia.
Read more about this topic: Green Manure
Famous quotes containing the words green, manure and/or crops:
“With sudden roar and aged pine-tree falls,—
One crash, the death-hymn of the perfect tree,
Declares the close of its green century.”
—Ralph Waldo Emerson (1803–1882)
“Humanity is the rich effluvium, it is the waste and the manure and the soil, and from it grows the tree of the arts.”
—Ezra Pound (1885–1972)
“Paper is cheap, and authors need not now erase one book before they write another. Instead of cultivating the earth for wheat and potatoes, they cultivate literature, and fill a place in the Republic of Letters. Or they would fain write for fame merely, as others actually raise crops of grain to be distilled into brandy.”
—Henry David Thoreau (1817–1862)