Cation
Exchange Capacity (CEC)
The CEC is the abbreviation for the cation
exchange capacity of the soil. Any element with a positive
charge is called a cation. It refers to the basic cations,
calcium (Ca+2), magnesium (Mg+2), potassium (K+1) and sodium
(Na+1) and the acidic cations, hydrogen (H+1) and aluminum
(Al+3). The amount of these positively charged cations a soil
can hold is described as the CEC of the soil. The larger
the number, the more cations the soil can hold. The CEC
gives an indication of the soils potential to hold plant
nutrients.
Optimum Soil Levels
of Plant Nutrients
NOTE: The following plant nutrient levels are
not crop sensitive, please consult with your local
agronomist.
Mineral
Optimum Level
Phosphate
(P2O5)
220 - 280
lbs/acre
Potash
(K2O)
300 - 550
lbs/acre
Magnesium (MgO)
300 - 550
lbs/acre
Calcium (CaO)
2000 - 6000
lbs/acre
Copper,
Cu
0.5 - 2.0 ppm/acre
Iron,
Fe
2.0 - 50.0 ppm/acre
Manganese, Mn
15.0 - 45.0 ppm/acre
Zinc,
Zn
1.0 - 4.0 ppm/acre
Boron,
B
0.6 - 2.0 ppm/acre
Sulfate,
SO4
15.0 - 25.00 ppm/acre
The Roles Nutrients Play in Sod & Turf Soil
Macronutrients
Nitrogen:
Developing a nitrogen fertility program is an important
decision that can affect the quality and durability of your turf
and or sod. Because of the many uses of turf, site conditions,
level of turf quality, and cost considerations, no single
nitrogen program fits all. There are many sources of nitrogen to
pick from, slow release and quick release. So it is helpful to
know how the product was formulated and its potential for
release.
Phorphorus:
Phosphorus is one of the 3 primary nutrients needed by turf
and sod as a regular fertilizer addition. Although it is present
in small amounts in turf tissue (0.3 - 0.55) percent on a dry
weighted basis, phosphorus is extremely important for rooting,
seedling development, cell division, and the synthesis of
various compounds used by the plant. The most important factors
affecting phosphorus availability to turf and sod are soil pH
and concentrations of iron, aluminum, manganese, and calcium.
Phosphorus is largely immobile in soils - meaning that it takes
a long time to move from the soil surface to the root zone.
Because of its poor immobility, phosphorus should be
incorporated into the soil prior to seeding or sodding at the
amount recommended on your soil report.
Potassium:
Potassium is a primary turf nutrient and is usually supplied
annually as fertilizer. It makes up about (1.0 - 2.5) percent of
the plant's dry matter weight. Its' primary role involves
regulating several important physiological processes. Potassium
activates plant enzymes used in protein, sugar, and starch
synthesis. It also plays a key role in maintaining turgor
pressure in plants. Thus it has a strong influence on drought
tolerance, cold hardiness, and disease resistance. Potassium is
mobile in plants and sometimes can be taken up in amounts
greater than needed for optimum growth. It is generally
considered inefficient use of the nutrient.
Calcium, Magnesium, % Sulfur:
Calcium, magnesium, and sulfur are generally considered to be
secondary nutrients because in most cases they only occasionally
need to be supplied to turf in the form of fertilizer.
Applications of calcium and magnesium are usually only necessary
when the soil pH is below optimum standards for growth. Sulfur
is sometimes used to lower the soil pH where a high soil pH can
cause turf problems. Sulfur is usually only necessary in western
states where arid conditions lead to alkaline soils. In the
northeastern United States, high pH values are rarely a problem
and there is usually enough sulfur in soils to supply turf
needs.
Micronutrients:
The seven micronutrients required by turf include iron,
manganese, zinc, copper, molybdenum, boron, and chlorine.
Micronutrients are needed by turf in minute amounts and rarely
need be supplied to turf growing in mineral soils. However, when
turf are grown in high-sand-content soils (golf course putting
greens and some trees) or high pH soils, micronutrient
applications can be beneficial.
