Green manure

A crop grown and incorporated into soil to add organic matter and nutrients, improve soil structure, or suppress weeds.

Nitrogen fixation: The biological conversion of atmospheric nitrogen gas into compounds organisms can use. Legume green manures can add biologically fixed nitrogen to soil.
Legume: A plant in the family Fabaceae, many members of which form nitrogen-fixing symbioses with bacteria. Legumes are chosen when adding nitrogen is a main goal.
George Washington Carver: An American agricultural scientist who promoted crop diversification and soil-restoring farming in the early twentieth century. Carver advocated legumes and rotation to restore soils depleted by cotton production.
Erosion control: Practices that reduce the removal of soil by water or wind. Living cover and crop residues can shield soil during periods between cash crops.
Decomposition: The breakdown of organic matter by organisms into simpler substances. Soil organisms release nutrients as incorporated green-manure crops decompose.
Cereal rye: A winter cereal grass grown for grain, forage, or soil cover. Its winter growth and dense residue can suppress weeds and protect soil.
Jethro Tull: An English agricultural writer and inventor associated with eighteenth-century improvements in drilling and horse-hoeing. His advocacy of intensive cultivation contrasted with later emphasis on soil-building crop residues.
Nitrate leaching: The downward movement of nitrate through soil with percolating water. A growing cover crop can capture residual nitrate that might otherwise leach.
Soil organic matter: The decomposed and decomposing remains of plants, animals, and microorganisms in soil. Green-manure residues increase the organic material that supports soil structure and fertility.
Buckwheat: A fast-growing broadleaf crop cultivated for seed, forage, or soil cover. Its rapid growth makes it useful for short green-manure intervals.

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