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Healthy Turf Growth Through Proper Base Saturation

By Achille Correggia, B.Sc. (Agri.) Agronomy, CCA-ON

Soil can be defined as a complex medium of both organic and inorganic material, providing water and nutrients to turf for healthy growth and development. Nutrients that are required by turfgrass are retained on the surface of soil particles and organic matter known as the soil exchange sites. The total number of nutrient exchange sites on the soil surface is referred to as the Cation Exchange Capacity (CEC) of the soil. Elements with a positive charge are called cations, referring to Calcium (Ca+2), Magnesium (Mg+2), Potassium (K+1), Sodium (Na+1), Hydrogen (H+1), and Aluminum (Al+3) all of which, in proper balance, are necessary elements for healthy turfgrass growth. Soils that are predominantly clay will generally have a higher CEC value than sand based soils and the higher the CEC, the richer the soil is in nutrients.

Cation concentrations on the soil particle are expressed as a percent base saturation. The base saturation tells us what percent of the soil exchange sites are occupied by a certain cation. The general rule for soil base saturation is 60-80 percent Calcium, 10-20 percent Magnesium, 2-6 percent Potassium, 10-15 percent Hydrogen and 2-4 percent other cations (Iron, Manganese, Copper, Sodium and Zinc) covering the soil particle surface.

Should the percent base saturation of a soil deviate from the above ratios, turfgrass may exhibit signs of nutrient deficiencies. One excellent example of this is an excessive saturation of sodium. Soils that have sodium concentrations above normal levels, may exhibit the characteristics of compaction. Areas that may be prone to higher levels of sodium include boulevards and sidewalk edges. Sodium has a unique physical characteristic that brings soil particles closer together reducing large pore spaces. This physical change of the soil can reduce water infiltration, decrease the availability of oxygen, and hinder root growth. Any reduction in root growth can potentially decrease the amount of nutrients available to turf, ultimately affecting it’s competitive abilities against weeds.

One method used to reduce sodium levels in the soil and increase turfgrass health is the application of calcium. This addition increases the percentage of calcium attached to the soil particle and combined with irrigation reduces the sodium concentration associated with tight soil.

A product that is an excellent source of calcium is Nu-Cal S. Nu-Cal S is a premium source of granulated gypsum that provides nine percent soluble calcium, ten percent sulphur, and four percent magnesium without affecting the pH of the soil. Nu-Gro’s Nu-Cal S is available in a fine grade SGN size of 120; this smaller size improves the penetration of the granules through the turf canopy to the soil surface. In addition to improved canopy penetration, these highly soluble, finer grade granules can potentially reduce the time required to correct soil problems, as they readily dissolve into the soil solution fostering far more rapid results than traditional gypsum products.

General Soil Base Saturation Rule

Reference

• Street, J., Watson, M., Pound, W., (2005). Interpreting a soil test for lawns. Retrieved April 29 2005, from Ohio University, Extension Service Web site: http://ohioline.osu.edu/hyg-fact/4000/4028.html
• No author, (no data). What is the use for the cation exchange capacity (CEC) and the percent base saturation on the soil test reports? Retrieved April 29 2005, from http://hubcap.clemson.edu/~blpprt/bobweb/BOBWEB23.HTM
• No author, (no date). Cation exchange capacity and percent base saturation. Retrieved April 29 2005, from http://hubcap.clemson.edu/~blpprt/IL64.html
• Patterson, G. (2003). A&L Labs soil testing presentation.
• No author, (2004). Nu-Cal S Spec Sheet from the Nu-Gro Corporation
• Whiting, D., Wilson, C., and Card, C. (2005). Soil Compaction, Retrieved from Colorado State University Cooperative Extension Web site: http://www.ext.colostate.edu/pubs/garden/07724.html

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