Common Liming Terms

ACID FORMING FERTILIZER- A fertilizer that is capable of lowering the pH (increasing the acidity) of the soil following application.

AGLIME- Also know as "agstone". Calcitic or dolomitic limestone that is crushed and ground to a graduation of fineness that will allow it to neutralize soil acidity. Usually material is ground to pass sieves from 8- to 100- mesh range or finer.

AGRICULTURAL LIMING MATERIAL- Any material that contains calcium and magnesium in forms that are capable of reducing soil acidity.

BURNT LIME- See calcium oxide.

CALCITE- The crystalline (having the regular internal arrangement of atoms, ions or molecules characteristic of crystals) form of calcium carbonate. Pure calcite contains 100% calcium carbonate (40% calcium). Calcite occurs in nature, limestone is not available commercially of this purity. It may be colorless, but is usually tinted by impurities.

CALCITIC LIMESTONE- A widely used term that refers to agricultural limestone with a high calcium content. Contains mainly calcium carbonate, but may also contain small amounts of magnesium. There are no regulations or restrictions governing the calcium or magnesium content.

CALCIUM (Ca) - Occurs in nature only in combination with other elements, does not occur solely as calcium. One of the 16 essential plant nutrients. It along with magnesium is one of the two main ingredients in limestone. Calcium is an essential part of teeth, bone and shells.

CALCIUM CARBONATE (CaCO3) - A compound which contains calcium combined with carbonate. It occurs in nature as limestone, marble, chalk, marl, shells, and similar substances.

CALCIUM CARBONATE EQUIVALENT (CCE) - Expression of the acid-neutralizing capacity of a carbonate rock relative to that of pure calcium carbonate (e.g. calcite). It is expressed as a percentage. For pure calcite the value is 100%, pure dolomite the value is 108.5%. Actual CCE of most limestone will vary from these percentages due to impurities in the rock, and the fact that most commercially available limestones have a mixture of calcite and dolomite rather than either in its pure form.

CALCIUM OXIDE (Ca0) - Chemical compound containing calcium and oxygen. Calcium oxide does not occur in nature, it is the formed from calcium carbonate by heating limestone to drive off the carbon dioxide.

CALCIUM OXIDE EQUIVALENT- The percentage of calcium oxide in a liming material plus 1.39 times the magnesium oxide content. For pure calcite, the value is 56.0%, for pure dolomite the value is 60.8%. Used by some states as a measure of aglime quality.

CAUSTIC LIME- See calcium oxide.

DOLOMITE- Limestone that contains magnesium carbonate (MgCO3) in an amount approximately equivalent to the calcium carbonate content in the stone. Limestone containing magnesium carbonate in lesser proportions is referred to as magnesian limestone or dolomitic limestone. Pure dolomite is 54.3% CaCO3 and 45.7& MgCO3 or expressed another way, is composed of 30.4% CaO, 21.8% magnesia (MgO), and 47.3% CO3.

DOLOMITIC LIMESTONE- Limestone that contains from 10%, but less than, 50% dolomite, and from 50-90% calcite. The MgCO3 content of dolomitic limestone may range approximately from 4.4-22.6%.

EFFECTIVE CALCIUM CARBONATE EQUIVALENT- An expression of aglime effectiveness based on the combined effect of chemical purity (CCE) and fineness. It is required for labeling purposes in some states. Determined by multiplying CCE by a set of factors based on the fineness of grind of the limestone. Also referred to as effective neutralizing value (ENV), total neutralizing power (TNP), effective neutralizing material (ENM) and, in one state, as the "lime score".

EFFECTIVE NEUTRALIZING POWER (ENP)- This is a term used in Ohio. It means the neutralizing value of liming material base on the ECCE (effective calcium carbonate equivalent expressed as a dry weight. It is used to take into account for the amount of moisture (water, etc) that maybe present in liming materials.

FINENESS INDEX- The percentage by weight of a liming material that will pass designated sieves. It is calculated to account for particle distribution by totaling the amounts of material that are held and /or passed through the various sieve screens as determined by various state liming regulations and guidelines.

FLUID-BED ASH- Byproduct of electrical utility companies from mixing limestone into ground coal in a fluidizing bed to control burning rates of coal. The ash remaining after burning the coal has a neutralizing value for correcting soil acidity. Ashes and dusts collected from smoke stacks also can neutralize soil acidity. The calcium carbonate equivalence can vary widely from these sources and should be determined by laboratory analysis. Application rates need to be adjusted for the relative neutralizing value of these materials.

FLUID LIME- Also known as "liquid lime". This product is made by mixing very finely ground limestone (100% passing a 100 mesh sieve and 89-90% passing a 200 mesh sieve) with either water or liquid nitrogen fertilizer along with a suspending agent (attapulgite clay) and applying with a liquid fertilizer applicator.

GYPSUM- A hydrated form of calcium sulfate (CaSO4). It supplies calcium to the soil, but it is a neutral substance and does not correct soil acidity; therefore it is not a liming material.


HYDRATED LIME- Produced by adding water to burned lime or by absorption of moisture from the air. It has the same characteristics and limitations as burned lime.

LIME- Chemically it is calcium and magnesium oxide. Produced by high temperature heating calcitic or dolomitic limestone, which will replace the carbonate ion (CO3--) of the limestone with oxygen. However, the term is broadly applied in agriculture to any material containing calcium and magnesium in forms capable of correcting soil acidity.

LIME REQUIREMENT- The amount of agricultural limestone required to move the soil acidity to reach another degree of acidity or pH. The desired pH range will depend on if the crop is an acid loving or more alkaline loving crop. It is usually expressed in pounds per acre of CaCO3 needed to bring the soil to the desired pH under field conditions.

LIME SLUDGES- Some water softening plants have lime sludge containing fine lime particles that are precipitated in the softening process. Lime sludges vary in calcium carbonate equivalent (CCE) and water content, both of which would influence the amount of sludge, needed to equal dry aglime.

MAGNESIAN LIMESTONE- Limestone that contains 5-10% pure dolomite, and 90 - 95% calcite. The MgCO3 content of magnesian limestone range from 2.3-4.4%.

MAGNESIUM CARBONATE- A compound consisting of magnesium combined with carbonate. It occurs in nature as the mineral magnesite and as an essential part of dolomitic limestone and dolomite.

MAGNESIUM OXIDE (MgO) - The chemical compound composed of magnesium and oxygen. It is formed from MgCO3 by heating to drive off the carbon dioxide, or in mixture with CaO by heating magnesian limestone or dolomite. Also known as magnesia, it occurs in nature as periclase.

MARBLE- A compact, hard, polishable form of limestone.

MARL- A granular or loosely consolidated, earthly material composed largely of calcium carbonate as seashell fragments. It contains varying amounts of silt and organic matter.

MECHANICAL ANALYSIS- Also referred to as screen or sieve analysis. Indicates the percentages of a material that fall within predetermined particle size limits and between certain mesh sizes. State laws governing aglime quality standards are all based on particle size distribution guidelines established by mechanical analysis.

PELLETIZED LIME- Limestone which is granulated into a pellet. The original product is a finally ground limestone (usually 100-mesh or smaller) in size that is put into a granulation drum and bound together with a highly water-soluble substance. This process improves the easy of handling and application of liming materials. In regards to correcting soil acidity, it takes the same amount of effective calcium carbonate equivalent pelletized lime as it does any other liming material to achieve correction of soil acidity.

QUICKLIME- See calcium oxide.

SLACKE LIME- See hydrated lime.

SLAGS- One of the steel industry byproducts is magnesium silicate or slag. Air-cooled slags must be ground the same as limestone. Water cooled slag is a porous granular material produced when water is applied to the hot slag. Because of the large particles associated with this material, it usually requires screening.

SOIL pH- An expression of the degree of acidity or alkalinity of a soil, measured on scale of 1 to 14. Readings from 1.0 to 6.9 indicate that a soil is acid (sour); from 7.1 to 14.0 that it is alkaline (sweet). A reading of 7.0 is neutral. The term "pH" refers to negative logarithm (p) of the hydrogen ion (H) concentration in soil solution.

SOIL REACTION- The acidity or alkalinity status of a soil. Soils that are acid are said to have and acid reaction; those that are alkaline, and alkaline reaction.

STACK DUST- See fluid-bed ash.

UNSLAKED LIME- See Calcium oxide.