Agronomic Dictionary

The mass of oven-dry soil per unit volume, usually expressed as grams per cubic centimeter.

The sum total of exchangeable cations that a soil can adsorb at a specific pH. Expressed as centimoles of charge per kilogram (cmolc/kg) of soil or milliequivalents per 100 g of soil (meq/100 g of soil).

Increasing the soil bulk density, thereby decreasing the soil porosity, by the application of mechanical forces to the soil.

The nutrient tissue or soil concentration falling just between deficiency and sufficiency for a given crop.

The amount of nutrients needed to grow a specified yield of a crop.

A planned sequence of crops growing in a regularly recurring succession on the same area of land.

The wearing away of the land surface by running water, wind, ice, geological agents, or mechanical erosion.

Elements that are required for growth and development of plants C, H, O, N, P, K, Ca, Mg, S, B, Cl, Cu, Fe, Mn, Mo, Ni, Zn.

Loss of water to the atmosphere from the soil surface by evaporation and by transpiration through plants.

Applying fertilizer through an irrigation system.

Organic or inorganic material added to a soil to supply one or more nutrients essential to plant growth.

The amount of water a soil holds after free water has drained due to gravity.

Application of a dilute solution of fertilizer to plant foliage, usually made to supplement soil-applied nutrients.

Water that moves through the soil under the influence of gravity.

Living plant material incorporated into the soil, or killed and left on the surface, for soil improvement, or when composed of legumes to increase the soil N supply.

Water in the saturated zone below the soil surface

Minimum quantities of available nutrients contained in a fertilizer material, stated as percentages on the fertilizer material’s label.

A plant nutrient that moves only slowly in the soil or plant.

The conversion of an element from the inorganic to the organic form in microbial tissues resulting in that element not being readily available to other organisms or plants.

Mineral forms of nitrogen.

A salt of phosphoric acid or any of its anions, usually orthophosphate or polyphosphate.

A material capable of neutralizing soil acidity.

The amount of liming material required to change the soil pH to a specific desired value.

The absorption by plants of an essential nutrient in excess of the need for growth. Luxury concentrations in early growth may be used in later growth.

A nutrient that a plant needs in relatively large amounts. Essential macronutrients are nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S).

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.

The conversion of an element from an organic form to an inorganic form by soil organisms.

Also called conservation tillage, is a soil conservation system like Strip-till with the goal of minimum soil manipulation necessary for a successful crop production. It is a tillage method that does not turn the soil over.

A nutrient that moves readily in the soil or plant.

An inorganic nitrogen form that is very soluble, easily leached from soils, readily available to plants, and readily denitrified

A form of nitrogen resulting from the first step in nitrification by soil microbes. Nitrite is subsequently oxidized to nitrate (NO3) by other soil microbes.

Essential nutrient for plants and animals. Nitrogen is a component of chlorophyll, enzymes, amino acids, and nucleic acids.

An increase in soil levels of a nutrient due to application of that nutrient at rates that are greater than crop removal.

A decrease in soil levels of a nutrient due to application of that nutrient at rates that are less than crop removal.

Nitrogen that is bound with organic carbon and forms organic molecules.

Phosphorus that is bound with organic carbon and forms organic molecules.

An inorganic form of plant available phosphorus.

Phosphorus pentoxide, phosphate; used in a fertilizer analysis to denote the percentage of available phosphorus expressed as P2O5.

The soil water content at which most plants cannot obtain sufficient water to prevent permanent tissue damage.

Essential nutrient for plants and animals. Component of cell walls, nucleic acids, and energy transfer molecules.

Plant material (roots and shoots) that remains in the field after harvest.

Potassium oxide, potash; used in a fertilizer analysis to denote the percentage of water soluble potassium expressed as K2O.

Essential nutrient for plants and animals. Involved in plant moisture regulation, energy metabolism, starch synthesis, and sugar degradation.

Using the best technologies to identify and manage in-field soil and crop variability to improve production and economic return.

The three macronutrients used by plants in the largest quantities: nitrogen, phosphorus, and potassium.

A prescribed amount of nutrients to apply based on soil or plant analysis, crop removal, projected crop yields, or other crop-related factors.

The macronutrients of calcium, magnesium, and sulfur.

Soil is a dynamic natural body composed of mineral and organic materials and living forms in which plants grow. Soil also is the collection of natural bodies occupying parts of the earth’s surface that support plants and that have properties due to the integrated effect of climate and living matter acting upon parent materials, as conditioned by relief, over periods of time.

A chemical, physical, or biological procedure that estimates soil characteristics relative to plant growth and the potential of a crop growth response to additional nutrients.

The organic fraction of the soil exclusive of undecayed plant and animal residues. Often used synonymously with “humus”.

The degree of acidity or alkalinity of a soil, expressed on a scale from 0 to 14, with 7.0 indicating neutrality. Increasing values indicate increasing alkalinity, while decreasing values indicate increasing acidity

A measure of the soil’s ability to produce a particular crop or sequence of crops under a specific management system.

The aqueous liquid phase of the soil and its solutes contained in soil pores.

The combination or arrangement of primary soil particles into secondary soil particle units, or peds.

The relative proportions of sand, silt, and clay in the soil.

Sequences of operations that manipulate the soil in order to produce a crop. Operations include tilling, planting, fertilization, pesticide application, harvesting, and residue chopping or shredding.

The sum of the organic and inorganic forms of nitrogen in a sample.

A quantity of a material in plants, soil, or water that can harm or impair the physiological function of plants or soil microbes

Refers to the application of a material, such that the rate of application is based on the precise location, or qualities of the area that the material is being applied to.

The ability to vary the application of crop production inputs based on criteria for crop response or soil conditions. VRT allows for the targeted application of inputs at varying rates across a field.