Sustainable Soil Management
Glossary
P
PARENT MATERIAL. The unconsolidated and more or less chemically weathered mineral or organic matter from which the solum of soils is developed by pedogenic processes.
PED. A natural soil aggregate, such as a granule or prism.
PERMAFROST. Permanently frozen material underlying the solum.
PERCOLATION. Downward movement of water through soil or rock.
PERMANENT WILTING POINT. The soil water content at which most plants cannot obtain sufficient water to prevent permanent tissue damage.
PERMEABILITY. Capacity of soil, sediment, or porous rock to transmit water and gases.
PHOSPHORUS. Essential nutrient for plants and animals. Component of cell walls, nucleic acids, and energy transfer molecules.
PLANT AVAILABLE NITROGEN (PAN). A calculated quantity of nitrogen made available during the growing season after application of fertilizer. PAN includes a percentage of the organic nitrogen, a percentage of the ammonium N, and all the nitrate nitrogen in the fertilizer.
PLANT RESIDUES. Plant material that remains in the field after harvest.
PLATY. A soil structure consisting of soil aggregates that are developed predominantly along the horizontal axis; laminated; flaky.
PLOW PAN. A subsurface soil layer having a higher bulk density and lower total porosity than layers above or below it, as a result of pressure applied by normal plowing and other tillage operations.
POTASH. Term used to refer to potassium or potassium fertilizers.
POTASSIUM. An essential plant nutrient involved in energy metabolism, starch synthesis, and sugar degradation.
PRECISION FARMING. The spatially variable management of a field or farm based on information specific to the soil or crop characteristics of many very small subunits of land. This technique commonly uses variable rate equipment, geo positioning systems and computer controls.
PRISMATIC (COLUMNAR). Soil structure where the individual units are bounded by flat or slightly rounded vertical faces. Units are distinctly longer vertically, and the faces are typically casts or molds of adjoining units. Vertices are angular or sub-rounded; the tops of the prisms are somewhat indistinct and normally flat.
