Michigan State University Extension
Soils & Soil Management - Fertilizer - 06039705
07/10/97
Tri-state Fertilizer Recommendations for Corn, Soybeans, Wheat and Alfalfa Extension Bulletin E-2567 (New), July 1995
M.L. Vitosh, Michigan State University; J.W. Johnson, The Ohio State University; D.B. Mengel, Purdue University; Co-editors
After the sample has been collected, contamination must be avoided. Common sources of contamination include dirty sampling tools, storage vessels and surfaces on which soils are spread to dry. Ashes from tobacco products can cause considerable contamination of soil samples. Soils should be shipped to the testing laboratory only in containers approved by the lab.
Individual cores should be mixed thoroughly to form a composite sample. Moist cores should be crushed into aggregates approximately 1/8 to 1/4 inch across for optimum mixing. If the mixed sample is to be dried, the drying should be done at temperatures no greater than 120 degrees F (50 degrees C). After drying, a subsample of appropriate size should be taken from the composite mixture and sent to the testing laboratory for analysis.