A South Dakota NAPT soil processed at 2MM (Left) and 0.8MM (right). Fine sieving did not affect Solvita respiration but significantly increased Amino-N recovered and decreased aggregates

A recent Soil Sieving Study examines how soil sieving for proficiency samples affects soil health test parameters. The work, a collaboration of Brinton and the Utah State PSC appears in the international peer-reviewed Agriculture Research and Technology Journal. A focus of the study was if CO2 respiration would be influenced by soil sieving finer than 2 mm. The paper reflects a concern first raised by Brinton in 2015 at the in Minneapolis, that rough handling of soils by commercial labs created artifacts in respiration. The current project also included amino-N (SLAN) and water-stable aggregates, tests included in soil health programs. The research concluded that with careful moisture addition, and avoidance of Haney wetting methods, CO2 respiration could be as accurately performed at 0.8mm and 2mm sieve size (finer sieving was not investigated). However, sieve size very significantly altered amino-N results (increasing them) and aggregates (decreasing them), confirming that soil handling may create artifacts depending on which soil health tests are employed.

Brinton’s paper which also examined the literature for earlier work on soil prepping for microbial testing is available on-line under or at DOI.