|When comparing results from one laboratory to the next it is important to determine the following: |
- Laboratory method used for each analysis.
- Units reported for each analysis.
- Any conversion or calculation used for specific tests.
It is important to note that there is no perfect method for determining how much or little of an essential nutrient is available for plant uptake. Availability is affected by: soil moisture, temperature, soil pH, clay/organic matter content, soil drainage, physical barriers and many other factors. As these factors change the availability of nutrients also change. What a soil test measures is the degree of fertility; be it low, medium or high.
|Analysis ||Units ||Method Description |
|Soil pH ||N/A||1:1 Soil/Water Slurry |
|Soluble Salt ||mmhos/cm||1:1 Soil/Water Slurry |
|Buffer pH||N/A||Sikora Buffer Solution|
Ammonium Acetate Extraction
If pH < 7.2
If pH > 7.1
Bray I Extraction
|Sulfur||ppm||Monocalcium Phosphate (ICP Determination |
|Boron||ppm||Hot Water Extraction (ICP Determination|
|Nitrate-N ||ppm||Cadmium Reduction|
|Particle Size Analysis|
|Salinity Evaluation ||mmhos/cm||Saturated Paste Extraction |
|Other Methods Available || ||Pertains to country of origin|
|Extractable Soil Ammonium ||ppm||KCI extraction |
|Extractable Chloride in Soil||ppm||Calcium Nitrate Extraction|
|Soil Moisture||%||Loss of Drying|
|Organic Matter||%||Loss of Ignition|
|Extractable Aluminum||ppm||Cesium Chloride Extraction|
|Extractable Molybdenum||ppm||Ammonium Oxolate|
| || || |
|Nitrate-Nitrogen ||ppm ||2% Acetic Acid digestion |
|Phosphate-Phosphorus ||ppm||2% Acetic Acid digestion |
|Extractable Potassium ||%||2% Acetic Acid digestion|
|Total Nitrogen||% ||Kjeldahl Digestion |
|Total Phosphorus||%||Nitric Acid/Hydrogen Peroxide Digestion|
|Plant Minerals||% and ppm||Nitric Acid/Hydrogen Peroxide Digestion|
| || || |
GREENHOUSE MEDIA TESTING
|Media pH ||N/A||Saturated Media Extract (SMS)|
|Electrical Conductivity||mmhos/cm|| " |
|Phosphorus ||ppm|| " |
|Potassium || "|| " |
|Calcium || "|| " |
|Magnesium|| " || " |
|Sodium|| " || " |
|Zinc || " || " |
|Manganese|| " || " |
|Copper || " || " |
|Iron|| " || " |
|Boron|| " || " |
|Aluminum || " || " |
|Nitrate-N|| " || " |
|Ammonium-N || " || " |
|Organic Matter &|
Loss on Ignition
|Total Nitrogen||% ||Kjeldahl Digestion|
|Soluble P205||% ||Citric Acid Digestion|
|Soluble K20||%||Ammonium Oxalate|
- Analytic procedures used in US EPA Report SW-846, Test Methods for Evaluating Soil Waste, 3rd Edition, November 1990, as revised.
- Association of Official Analytical Chemists (AOAC) Official Methods of Analysis, 1990, 15th Edition.
- Methods of Soil Analysis, Parts I, II, and III. Soil Science Society of American. 1996.
- North Central Regional (NCR) Publication No. 221 (Revised). Recommended Chemical Procedures for the North Central Region Bulletin No. 499 (Revised) October 1988.
- Standard Methods for the Examination of Water and Wastewater, 18th Edition, 1992.
- The American Society for Testing and Materials (ASTM) Standard Tests Methods, 1988.
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