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Soil Analysis Results - Why It's So Very Important

  • A soil analysis provides essential information on relative levels of organic matter, pH, lime requirement, cation exchange capacity (CEC), and levels of plant-available nutrients contained in the soil.
  • Encourages plant growth by providing the best lime and fertilizer recommendations. 
  • Diagnoses whether there is too little or too much of a nutrient.
  • Promotes environmental quality.
  • Saves money that might otherwise be spent on unneeded lime and fertilizer. It can put money in your pockets!
  • How To Take Samples
    • Take samples in advance of applying any fertilizer or lime.
    • Use clean equipment.
    • Sample each unique area
    • Take a core sample to correct depth [4” for established lawn and 6” for landscape bed]
    • Collect at least 10 samples from the area you have identified and mix them together in a clean plastic bucket    

Soil Analysis Results - How to Interpret the Results

  • Report Number
    • All sample reports are filed by their report number.
  • Laboratory Number
    • This number is assigned Stewardship Labs to each individual sample.
  • ppm (parts per million)
    • Results for major and minor elements are reported in ppm on an elemental basis.
    • This unit of measurement is equivalent to pounds of nutrient per million pounds of soil.
    • One acre of mineral soil 3 to 3.5 inches deep weighs about a million pounds. 
  • Nutrient level ratings – individual nutrient elements are rated with five levels
    • Very low or low level means the soil is deficient and the addition of the element is beneficial for most plants.
    • Medium level means the addition of the element is beneficial to the plant 50% of the time. 
    • High level means enough nutrient is in the soil and the addition of the element is not likely beneficial to the plant, however some addition is needed to maintain a good fertility. 
    • Very high level means no additional nutrient is needed for most plants. It should be emphasized that at this level the plant can grow quite well and not suffer from toxicity.
  • Phosphorus
    • This test measures phosphorus that is readily available to plants.
    • The optimum level will vary with plant, yield and soil types.
    • 40 to 100 ppm is adequate for most lawn and garden plants.
    • Certain specialty plants may need higher levels.
  • Potassium
    • This test measures the available potassium in a soil.
    • The optimum level will vary with the plant, yield and soil type.
    • A potassium level of 120 to 200 ppm is adequate for most plants.
    • Higher levels are generally needed on soils high in clay and/or organic matter, versus soils that are sandy and low in organic matter.
  • Magnesium and Calcium
    • Calcium deficiencies are rare when the soil pH is adequate.
    • Magnesium deficiencies are more common.
    • Calcium will be in optimum range once lime is applied to adjust to the pH range appropriate for the plant.
    • Apply dolomitic lime if the magnesium falls below 70ppm.
  • Sulfur
    • This test measures sulfate-sulfur.
    • It is a readily available form preferred by plants.
    • Optimum levels usually range from 20 to 30 ppm.
  • Micro-nutrients (zinc, manganese, Iron, copper, boron)
    • Turf grasses need very little amount of these micro-nutrients and soil can provide enough if the pH is below 7.0.
    • For garden and flower plants, the adequate range for Zinc is 6 -10 ppm.
    • Manganese is 20-40 ppm.
    • Iron is 10-50 ppm.
    • Copper is 0.4-5.0 ppm.
    • Boron is 0.8-2.0 ppm.
  • Sodium
    • Sodium is a non-essential nutrient for most crops.
    • Its effect on the physical condition of a soil is of greater importance.
    • Soils high in sodium may cause adverse physical and chemical conditions.
    • Excessive levels of sodium can be reduced by leaching and/or through the application of calcium sulfate (Gypsum).
  • Soluble salts
    • Excessive concentrations of various salts can develop in soils.
    • This may be natural cause, the result of irrigation with high salt content water, excessive fertilization or contamination from chemicals or industrial waste.
    • Above 1900 ppm is hazardous and need leaching.
  • Soil pH
    • This test measures active acidity or alkalinity. A pH of 7.0 is neutral.
    • Values higher are alkaline while values lower are acid.
    • A pH of 6.0 to 7.0 is the desired range for most plants grown in mineral soils.
    • A pH of 5.0 to 5.5. is desired for organic soils (greater than 20% organic matter).
  • Acidity (H)
    • This represents the quantity of the acid.
    • For a given type of soil the lower the pH
    • The higher amount of acidity exists and more lime is needed to neutralize it.
  • CEC (Cation Exchange Capacity)
    • CEC measures the soil's ability to hold elements with positive charges (cations) such as calcium, magnesium potassium, sodium and hydrogen.
    • The CEC of a soil will increase with the increasing amount of clay and organic matter. 
  • Percent Base Saturation
    • This is the proportion of the CEC occupied by a given cation or a combination of cations referred to as bases.
    • Based on ideal soil concept, soil should have 85 to 90% base saturation, that is 65 -75% Ca, 10-15% Mg, 2.5-5.0% K, 5-13% H. 
  • Organic matter
    • Organic matter is expressed in percent.
    • It measures the amount of decomposed plant and animal residues in a soil.
    • Soil color is closely related to the amount of organic matter.
    • A darker color is usually associated with high organic matter.
    • Dark -colored soils often test above 3.5% organic matter.
    • Organic matter can improve soil physical properties and enhance plant growth.
    • High number is good but 3 -5% is sufficient.