<< Previous Page  Page 3 of 4  Next Page >>

17. Nitrate-Nitrogen (N): Nitrogen is reported in lbs/acre. Nitrate-nitrogen is mobile in the soil solution and should be tested to a minimum of 24 inches for most crops. For deep rooted nitrogen sensitive crops, such as sugar beets, nitrogen should be tested to 48 inches. Relative levels for nitrogen (0-24" samples) in the soil are: Very Low = 0-37 lbs/acre, Low = 38-74 lbs/acre, Medium = 75-111 lbs/acre, High > 111. Sandy well drained soils often have low nitrate levels. If nitrogen levels in the top soil are low, additional nitrogen fertilizer may be necessary to supply nitrogen early in the season.

18. Phosphorus (P) (Olsen-Bicarbonate phosphorus test can be used on both acid and basic soils): The Olson-Bicarbonate phosphorus test is reported in ppm. Phosphorus is not mobile in the soil and should be test on the topsoil (0-6"). Relative levels for Olsen-Bicarbonate phosphorus test are: Very Low = 1-3 ppm, Low = 4-7 ppm, Medium = 8-11 ppm, High = 12-15 ppm, Very High > 15 ppm.

19. Phosphorus (P) (Bray 1 phosphorus test should be used on soils with pH less than 7.0): The Bray 1 phosphorus test is reported in ppm. Phosphorus is not mobile in the soil and should be tested on the topsoil (0-6"). Relative levels for Bray 1 phosphorus test are: Very Low = 1-5 ppm, Low 6-10 ppm, Medium 11-15 ppm, High = 16-20 ppm, Very High > 20 ppm.

20. Potassium (K) (Ammonium Acetate Exchangeable K test): Potassium is reported in ppm. Potassium is not generally mobile in the soil and should be tested on the topsoil (0-6"). Relative levels for potassium are: Very Low = 1-40 ppm, Low = 41-80 ppm, Medium = 81-120 ppm, High 120-160 ppm, Very High > 160 ppm. Sandy soil types are often low in potassium.

21. Chloride (Cl): Chloride is reported in lbs/acre. Chloride is mobile in the soil solution and should be tested to a depth of 24". Relative levels for chloride are: Very Low = 1-15 lbs/acre, Low = 16-30 lbs/acre, Medium = 31-45 lbs/acre, High = 46-60 lbs/acre, Very High > 60 lbs/acre for 0-24" samples. Soils that have never had potassium chloride (potash) fertilizer applied and are nonsaline are often low in chloride. Small grains (wheat, barley, rye) are most sensitive to low soil chloride levels.

22. Sulfur (S-sulfate): Sulfur is reported in lbs/acre. Sulfur is mobile in the soil solution and should be tested to a depth of 24 inches. Relative sulfur levels are: Very Low =< 1-25 lbs/acre, Low = 26-59 lbs/acre, Medium = 60-120 lbs/acre, High > 120 lbs/acre for 0-24' samples. Sandy well drained soils are often low in sulfur. Shallow rooted crops or crops with high sulfur requirements (i.e. canola) may require higher rates of sulfur fertilizer.

23. Boron (B): Boron is reported in ppm. Boron is mobile in the soil solution. Boron should be tested on the topsoil (0-6"). Relative levels for boron are: Very Low = .1-.4 ppm, Low = .5-.8 ppm, Medium = .9-1.2 ppm, High = 1.3- 1.6 ppm, Very High > 1.6 ppm. Sandy well drained soils are often low in boron. Crops most sensitive to boron include alfalfa and clover.

24. Zinc (Zn): Zinc is reported in ppm. Zinc is not mobile in the soil solution and should be tested on the topsoil (0-6"). Relative levels for zinc are: Very Low = .1-.3 ppm, Low = .4-.6 ppm, Medium = .7-1.0 ppm, High = 1.0-2.0 ppm, Very High > 2.0 ppm. Soils with high pH often test low in zinc. Crops most sensitive to zinc include corn, flax, potatoes and edible beans.

25. Iron (Fe): Iron is reported in ppm. Iron is not mobile in the soil and should be tested on the topsoil (0-6"). Relative levels for iron are: Very Low = .1-2.5 ppm, Low = 2.6-5.0 ppm, Medium = 5.1-7.5 ppm, High = 7.6-10.0 ppm, Very High > 10.0 ppm. Crops most sensitive to iron include flax and most beans. Iron chlorosis often occurs on soils high in carbonates, high in soluble salts, or poorly drained soils regardless of soil iron levels.

26. Manganese (Mn): Manganese is reported in ppm. Manganese is not mobile in the soil and should be tested on the topsoil (0-6"). Relative levels for manganese are: Very Low = .1-1.0 ppm, Low = 1.1-2.0 ppm, Medium = 2.1-3.0 ppm, High = 3.1-4.0 ppm, Very High > 4.0 ppm. Soils with high pH and high organic matter are often low in manganese.

27. Copper (Cu): Copper is reported in ppm. Copper is not mobile in the soil and should be tested on the topsoil (0-6"). Relative levels for copper are: Very Low = .1-.2 ppm, Low = .3-.4 ppm, Medium = .5-.6 ppm, High .7-.8 ppm, Very High >.8 ppm. Deep sandy soils with low organic matter or peat and muck soils often are low in copper. Crops sensitive to copper are winter wheat, spring wheat, barley, oats and rye.

28. Magnesium (Mg): Magnesium is reported in ppm. Magnesium is not mobile in the soil and should be tested on the topsoil (0-6"). Relative levels for Magnesium are: Low 0-50 ppm, Medium = 51-100 ppm, High > 100 ppm. On very acid (pH 5.5 or less) sandy soil, magnesium deficiency may occur on alfalfa, corn, potatoes or onions.

29. Calcium (Ca): Calcium is reported in ppm. Calcium is not mobile in the soil and should be tested on the topsoil (0-6"). Relative levels are: Very Low = 1-250 ppm, Low = 251-500 ppm, Medium = 501-2,000 ppm, High = 2,0001-4,500 ppm, Very High > 4,500 ppm. Sandy soils with a pH < 6.0 my be calcium deficient.

30. Sodium (Na): Sodium is reported in ppm. Sodium is not a plant nutrient but is tested because it can destroy soil structure and productivity at high levels. Sodium is not mobile in the soil solution and is generally tested on the topsoil (0-6") soil sample. Relative levels for sodium are: Very Low = 1-40 ppm, Low = 41-80 ppm, Medium = 81-120 ppm, High = 121-160 ppm, Very High > 160 ppm. High levels of sodium reduce plant growth. High levels of sodium are often associated with high pH, irrigated soils and saline soils.

31. Organic Matter (OM): Organic matter is reported as percent. Organic matter levels in soil profiles are highest in the topsoil. Percent organic matter is determined on the topsoil (0-6"). Relative levels for organic matter are: Very Low = .1%-1.5%, Low = 1.6%-3.0%, Medium = 3.1%-4.5%, High = 4.6% - 6.0%, Very High > 6.0%, Peat > 15%. Sandy, well drained soils and eroded soils, are often low in organic matter. The rate of soil applied herbicides may be based on the organic matter level of the soil.

32. Soluble Salts (Electrical Conductivity): Soluble salts are measured by the soils ability to conduct electricity and is reported in millimhos/cm. The more electricity a sample conducts the higher the soluble salts in the soil. Soluble salts are mobile in the soil solution and will move up and down with the soil water table. Soluble salts are commonly tested to a depth of 24" or deeper. Relative levels of soluble salts are: Very Low = .01-.25 mmhos/cm, Low = .26-.50 mmhos/cm, Medium = .51-.75 mmhos/cm, High = .76-2.0 mmhos/cm, Very High > 2.0 mmhos/cm for each depth. High soluble salt levels severely affect plant growth. Crops vary widely in their sensitivity to soluble salts. High soluble salts are a major factor in soybean iron cholorosis.

33. Soil pH (pH): Soil pH is a measure of the hydrogen ion concentration of a soil. Soil pH is expressed on a logarithmic scale from 1.0-10.0. Soils with a pH < 7.0 are termed acid. Soils with a pH >7.0 are termed basic or alkaline. Crops vary widely in their sensitivity to soil pH. Soils with a pH of less than 6.5 may have lime applied to raise the soil pH. Crop sensitivity to soil pH varies widely and affects how much, if any lime needs to be applied. Soil pH also affects the availability on many nutrients.

34. Buffer pH: The Buffer pH is a test specifically designed to determine the amount of lime required to raise the pH of very acid soils. The Buffer pH test is reported on a logarithmic scale from 1.0-10.0. The buffer pH test is generally used on soils with a soil pH of less than 6.0.

35. Cation Exchange Capacity by summation (CEC): The CEC of soil is reported in milliequivalents/100 grams of soil. The CEC is determined on the topsoil (0-6"). The CEC of a soil is an index of a soils ability to hold all cations (Ca++, Mg++ ,Na+, K+, H+). The CEC of a soil is closely related to soil texture. A CEC of 1-8 = Sand, 9-12 = Loamy Sand, 13-20 Sandy or Silty Loam, 21-28 = Loam, 29-40 = Clay Loam and > 40 = Clay or Peat. The CEC of soils with a pH of less than 7.0 are accurately reflected by this test. Soils with pH > 7.3 can contain excessive carbonates which will inflate CEC values. The CEC of a soil may be used to adjust rates of soil applied herbicides.

36. Base Saturation: The base saturation of a soil is expressed on a percent basis. The percent base saturation for each cation is calculated from the total amount of calcium, magnesium, potassium, sodium and hydrogen measured in the topsoil. Each nutrient is expressed as a percentage of the total amount of cations measured in the sample (i.e. a soil may have 70% Calcium + 20% Magnesium + 7% Potassium + 3% Sodium = 100%) Typical ranges for base saturation are: Calcium 65-75%, Magnesium 15-20%, Potassium 1-7%, Sodium 0-5%, Hydrogen 0-5%.

37. Relative Test Level: Indicates the relative level of each test. The bar graph display is designed to make explaining the relative level of each test easier.

38. Carbonates: (also known as calcium carbonate equivalent (CCE) or percent free lime): This is a measure of the total calcium and magnesium carbonate present in the soil as precipitated solid or crystal. A high level of carbonate is one factor that has been shown to increase the iron chlorosis in soybeans. Soils with a high level of carbonate and soluble salts may express severe iron chlorosis in soybeans. Soils with a high level of carbonate may also require higher levels of phosphorus fertilizer application due to phosphorus combining with calcium to form calcium phosphates with a low solubility. Relative level of carbonate: Low = 0-2.5%, Moderate = 2.5-5.0%, High = 5.0-10%, Very High > 10.00%. Soils with a pH 7.3 or lower have little or no carbonate, but soils with pH 7.4 or higher may have low or high levels of carbonate. There is no way to tell the carbonate level of a soil with a pH higher than 7.4 without a soil test.

<< Previous Page  Page 3 of 4  Next Page >>