Sustainable Soil Management
Glossary
M
MACRONUTRIENT. A nutrient that a plant needs in relatively large amounts. Essential macronutrients are nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulphur (S).
MAPPING UNIT (SOIL). Basis for setting boundaries in a soil map. May include one or more soil series.
MASS FLOW. The movement of solutes associated with net movement of water.
METAMORPHIC ROCK. A rock that has been greatly altered from its previous condition through the combined action of heat and pressure. For example, marble is a metamorphic rock produced from limestone, gneiss is produced from granite, and slate is produced from shale.
MICRONUTRIENT. Nutrients that plants need in only small or trace amounts. Boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn) are considered micronutrients.
MINERAL SOIL. A soil whose traits are determined mainly by its mineral content; mineral soils contain less than 20 or 30 percent organic matter in the US and Canada, respectively.
MINERLIZATION. The conversion of an element by soil organisms from an organic form to an inorganic form.
MINIMUM TILLAGE. Tillage methods that involve fewer tillage operations than clean tillage does.
MOBILE NUTRIENT. A nutrient that moves readily in the soil or plant.
MOLLISOLS. An order in Soil Taxonomy. Soils with nearly black, organic-rich surface horizons and high supply of bases. They have mollic epipedons and base saturation greater than 50 percent in any cambic or argillic horizon. They lack the characteristics of Vertisols and must not have oxic or spodic horizons.
MONOAMMONIUM PHOSPHATE (MAP). A fertilizer composed of ammonium phosphates, resulting from the ammonization of phosphoric acid; typically, 11 percent N with an analysis of 11-52-0.
MORPHOLOGY, SOIL. The constitution of the soil, including the texture, structure, consistence, color, and other physical, chemical, and biological properties of the various soil horizons that make up the soil profile.
MULCH. Natural or artificial layer of plant residue or other material that conserves soil moisture, holds soil in place, aids in establishing plant cover, and minimizes temperature fluctuations.
MULCH TILL. A full-width tillage and planting combination that leaves some plant residues or other material on the soil surface.
MYCORRHIZA. The association, usually symbiotic, of fungi with the roots of seed plants.
