Our Soil Testing Methods
We use a variety of instruments to analyze soil samples including:
- atomic absorption spectrophotometers;
- Inductively Coupled Plasma Spectrometers (ICPs);
- Lachat Flow Injection Analyzer;
- colorimeters; and
- general laboratory equipment.
Brief descriptions of our soil testing methods are listed below.
At the laboratory, each sample is assigned an identification number, transferred to a paper bag, and then placed in a metal tray. Every 12th sample is a quality control sample, either a check sample of known chemical properties to ensure accuracy, or a duplicate sample to evaluate laboratory precision.
Samples are dried rapidly under forced air, the temperature not exceeding 95oF.
Dried samples are crushed with a mechanical grinder, and passed through a stainless steel 10-mesh 2.0 millimeter sieve to remove stones and unwanted debris.
Routine Soil Tests (regular tests)
- Estimated texture category
- Soil pH (1:1 suspension)
- Lime requirement (Sikora buffer index)
- Extractable phosphorus (Bray-1 extractant, Olsen-sodium bicarbonate extractant)
- Available potassium (ammonium acetate extractant)
- Organic matter (%) (loss on ignition)
Soil Tests Made Upon Request
- Soluble salts (electrical conductance, 1:1 soil suspension, saturation extract)
- Extractable sulfur (calcium phosphate extractant)
- Extractable zinc (DTPA extractant)
- Extractable zinc, copper, iron, and manganese (DTPA extractant)
- Nitrate-nitrogen (0.01 M CaSO4 extractant)
- Exchangeable magnesium and calcium (ammonium acetate extractant)
- Hot water extractable boron (0.1 % CaCl2.H2O)
- Environmental Lead (1 N HNO3 extractant)
- Nutrient Management Phosphorus (Olsen method)
Recommended Chemical Soil Test Procedures for the North Central Region. 1988 (revised 2015). North Central Regional Research Publication No. 221 (Missouri Agricultural Experiment Station SB 1001).