Knowledge is key to using your analytic results to their fullest. The Spectrum Agronomic Library provides you with useful information that will help you to better understand the complex science of agronomy. Our agronomists will be continually adding original and reprinted articles, so check the library regularly for new information.
As of July 1, 2005, Spectrum Analytic began reporting P, K, Ca, and Mg results as unadjusted Mehlich 3 (M3) values in parts per million (ppm). Prior to this date, samples were extracted with the Mehlich 3 solution, and the results mathematically converted to their equivalents in the older tests of Bray P1 for soil P, and 1Normal ammonium acetate (1NAoAc) for K, Ca, and Mg.
The table below shows the correlation formula we used to convert M3-ppm to the lbs/a values.
|Table 1: Correlation Formulas|
|M3-P||(ICP ppm x 0.7) x 2||Bray P1 in lbs/a|
|M3-K||(ICP ppm x 0.84) x 2||1NAoAc K in lbs/a|
|M3-Ca||(ICP ppm x 0.75) x 2||1NAoAc Ca in lbs/a|
|M3-Mg||(ICP ppm x 0.88) x 2||1NAoAc Mg in lbs/a|
For a complete explanation, see the original announcement of the change in Spectrum Analytic Reporting Conversions
Water is important nutrient to all livestock and poultry. As with feed ingredients, livestock water should meet the nutritional needs of the animal. Most minerals and dissolved solids found in water provide nutritional benefits when present within limited concentrations. This paper can be used as a guide to the recommended limits of certain substances commonly found in water used for livestock and poultry.
|Guidelines for Evaluating the Quality of Water for Livestock|
|Quality Factor||Threshold Concentration (ppm)||Limiting Concentrations (ppm)|
|Total dissolved solids (TDS)||2500||5000|
|Nitrate (see table for more detailed listing)||200||400|
|Sulfate (see table for more detailed listing)||500||1000|
|Range of pH||6.0 to 8.5||5.6 to 9.0|
A study by the University of Wyoming helps to answer the question of how lubricants affect soil test results. The study included five commonly used lubricants, two (motor oil and dish washing liquid) wiped on and three (WD-40, vegetable oil spray, and silicone) sprayed on the soil probe. Chemical composition of the lubricants is shown in Table 1.
|Table 1. Chemical Composition of Five Commonly Used Soil Probe Lubricants|
|“PAM” Vegetable oil spray||>70||9||34||1200||2.9||0.2||1.4||0.3|
|“Dove” dish washing liquid||30||205||44||2||0.2||<0.1||<0.1||<0.1|
|Synthetic motor oil||48||11||33||5||0.8||0.1||460||0.6|
Data shown in Table 1 indicates that lubricants can pose potential contamination problems. Their effects on test results for samples in the Wyoming study are shown in Table 2, and may be summarized as follows:
|Table 2. Effects of Soil Probe Lubricants on Soil Test Results|
|Control (no lubricant)||1.7||1||14||249||11.4||1.5||0.8||1.7|
|“PAM” Vegetable oil spray||1.7||2||16||263||13.5||3.8||1.1||2.3|
|“Dove” dish washing liquid||1.7||3||14||280||10.1||1.3||0.7||1.2|
|Synthetic motor oil||1.6||2||16||265||12.5||1.4||0.9||2.0|
Reference: Alan D. Blaylock, Lyle R. Bjornstead, and Joseph G Lauer, University of Wyoming. Taken from The Soil-Plant Council Analyst, The Soil and Plant Analysis Council, Inc. March 1996.