The following is a reference guide to understanding the components of your AgSource Harris Laboratory soil analysis. It provides a brief description of the essential nutrients along with the various ranges to allow you to effectively interpret your results.

Soil pH  Buffer pH  Excess Carbonate  Soluble Salt  Cation Exchange Capacity

Percent Base Saturation  Sodium  Organic Matter  Nitrate

Soil Nutrients (Potassium, Magnesium, Calcium)  Phosphorus

Zinc-Manganese-Copper-Iron

Soil pH is a measurement of the hydrogen ion concentration. Its presence or absence determines whether the soil is acidic or alkaline. Acid soils require limestone to raise the pH where as alkaline soils may need acid applications (elemental sulfur) to reduce soil pH. Most soils have a pH range from 4.0 to 8.5, with slightly acid conditions being most productive. However, different grass species vary in their ability to tolerate pH conditions.

Because soil pH measures the active hydrogen its value can be variable from one season to the next. This variability makes it difficult to predict the amount of lime necessary to increase pH to an optimum value.

This index was developed to measure the total hydrogen (acid) in the soil, which needs to be neutralized by limestone applications. As this index decreases the percentage of hydrogen increases. As a result, greater amounts of limestone are required. Because buffer pH is only used to predict the quantity of lime, it is only analyzed when the soil pH is less than 6.5.

This quick test measures the amount of free limestone in the soil. It is reported as; very low, low, medium, high and very high. As this rating increases so does the amount of free carbonate. This quantity has a direct affect on availability of plant nutrients, particularly with manganese, iron, zinc, and phosphorus, as it increases so does nutrient fixation rates. Excess carbonate can be neutralized with acid materials (elemental sulfur),however the quantity required can be so large that it may become toxic to turf grasses.

Soluble Salt is a measure of the soil's ability to conduct electricity. The more electricity conducted the higher the salt content in the soil. These salts are mobile in the soil solution and will move up and down with the soil water. Generally high salt levels are associated with soils which have poor drainage conditions. Salt accumulates at the soil surface rather than leaching down through the soil profile. Irrigation water can also contribute to this problem.

On this report soluble salt is analyzed as a 1:1 soil water ratio.

CEC establishes the rate at which nutrients (cations) will be stored and released. It is an estimated value based on the extracted cations from this soil analysis: (calcium Ca++, magnesium Mg++, potassium K+, sodium Na+ and hydrogen H+). Since the clay and organic sites in the soil have a negative charge, the positively charged cations bond with these sites. Therefore, CEC can be closely related to soil texture.

The five major cations in soils are hydrogen (H), potassium (K), magnesium (Mg), calcium (Ca), and sodium (Na). The actual percentage of each cation is reported on each of the MDS Harris reporting options along with the suggested percentage. By comparing the actual percentage with the suggested percentage, an idea of which kind of soil amendment (lime, gypsum, and sulfur) may or may not be needed.

Table representing the optimum percentage of the 5 major soil cations.

Sodium provides information relating to reclaiming saline and/or alkaline soils. When it's base saturation exceeds 5%, water infiltration rates can be reduced. This may not be the case on sand-based greens, where sand size (not soil structure) promotes infiltration. When correcting soils with high sodium, check and rate drainage conditions. This salt load can only be reduced by leaching it below the rooting zone. If appropriate, select one of these soil amendments: gypsum (CaSO4), epsom salts (MgSO4) or elemental sulfur (S).

Soil organic matter is the result of the decay process of organic residues. The result of this process is a stable humus compound which has active cation holding sites. These sites serve as a storehouse for plant nutrients and also improve soil structure in heavy soils. Undecomposed organic residue (thatch build up) is not organic matter.

In most productive soils, the top soil contains between 1.0 to 10.0 % OM. In golf course construction it is common to have this top soil either being buried or stripped away. These areas lose a valuable nutrient source. In addition, sand-based greens may contain zero or less than 0.5% OM. As a result greens have; high leach rate, low water holding ability, low nutrient content.

Nitrate-nitrogen is the amount of available nitrogen present in the soil at the time it was analyzed in the laboratory. Because of its solubility, it can leach rapidly in sandy soil conditions. This mobility makes it difficult to predict how much nitrogen will be present throughout the growing season. However, it can be a useful tool for determining nitrogen utilization efficiencies throughout the growing season.

These four cations are extracted with ammonium acetate and reported in parts per million (ppm).

The potassium extracted by ammonium acetate is readily available for plant uptake. Potassium is contained in the plant cells and tissues; therefore, it is removed in large quantities when vegetative growth is removed (removal of clippings).

The following table provides a generalized interpretation. As noted, soil texture influences availability, sandy textures do not have enough holding sites resulting in high leaching rates. Heavier textures will hold onto increasing amounts of K. As a result, high application rates are not advisable on sand based greens but can be successful on heavier textured fairways.

Magnesium, can be deficient in sandy soils with low organic matter. Applications can be as Epsom salts, dolomitic limestone or other soluble forms of Mg.

Calcium, is rarely deficient as a plant nutrient and usually applied as a soil amendment; limestone to increase soil pH, gypsum to exchange with sodium.

In the plant, phosphorus stimulates early growth and root formation. Its primary usage is in storage and transfer of energy throughout the plant.

These four micronutrients are extracted from the soil with DTPA solution. As general rule, soils which are; high in pH, low in organic matter and have a low CEC are often deficient in these trace elements.

On new construction and with extensive dirt work, zinc levels can start out as deficient, but over time, areas with high management (golf greens) can achieve a build up to very high levels. In turf grass, toxic levels have not been reported, however, monitoring is advisable.

Organic matter nutrient release is the primary source of manganese; therefore sand-based greens are usually deficient in Mn. In addition, Mn is highly reactive with soil pH. On pH's greater than 8.0 Mn applications plant response can be highly variable do to the very high fixation rates.

Copper is similar to Zn, in that it can start out as low in new construction and be built to very high levels with in several years. Monitoring is import, if a build up occurs check for a Cu source. Some soil applied fungicides contain high concentrations of Cu. Toxicities have not be established in turf grasses, however, levels greater than 10 ppm would be a concern.

Iron is similar to Mn in that it is highly reactive with pH. Soils with a pH greater than 8.0 can be sensitive to Fe deficiencies. In these soils iron fertilizer fixation rates can be high, so multiple applications will be necessary each season.