Sustainable Soil Management
Glossary
O
ORGANIC MATTER. The organic fraction of the soil exclusive of undecayed plant and animal residues.
ORGANIC NITROGEN. Nitrogen that is bound with organic carbon and forms organic molecules.
ORGANIC PHOSPHORUS. Phosphorus that is bound with organic carbon and forms organic molecules.
ORGANIC SOIL. Soil containing more than 20 or 30 percent organic matter in the US and Canada, respectively.
ORTHOPHOSPHATE. Inorganic form of plant available phosphorus.
OXISOLS. An order in Soil Taxonomy. Soils with residual accumulations of low-activity clays, free oxides, kaolin, and quartz. They are mostly in tropical climates.
