Soil microbes number up to 10-million per gram soil, and release free fertilizer for plants.

According to Will Brinton, soil labs may be reluctant to adopt soil biology tests due to complicated outdated (and costly) methods. “It’s too bad since this is impeding the country getting on with much needed soil quality assessment”. One older method, still sometimes used, measures microbial biomass by an indirect process called fumigation-incubation (FI). FI is complicated and requires use of toxic chloroform first to kill soil microbes, then inoculation, then a 10-day incubation for microbes to re-establish themselves, then a period of capture of CO2. “Talk about a convoluted,  costly way  to measure the microbial traits of a soil”. Will Brinton has worked with soil respiration since the late 1970’s and developed the breakthrough Solvita test, which allows soil microbial activity to be rapidly measured within 24hrs. Microbes are important since their activity releases free fertilizer that labs are not accounting for in their fertilizer recommendations.

PARTNERSHIP: The new soil Solvita CO2-burst protocol is a unique collaboration of Government and Private Lab: Woods End Laboratories and Dr. Haney’s USDA-ARS soil lab in Temple, TX, both centers that had been pursuing soil quality for the last 20 years. The new protocol puts the measurement of soil microbial activity into the realm of the practical and is extremely cost-effective from a commercial soil lab perspective. The simple method combines a pre-calibrated CO2-trap and a soil drying-and re-wetting step which simulates the natural potential to spring into activity, following a severe event (but not as severe as killing with chloroform).  Recent published research shows that 24h  CO2-burst  corresponds closely to bacterial biomass results, so it should be no problem to move forward with the new system. The thrust of the new work however is focused on nutrients released by microbes:

WHY TEST SOIL MICROBES: The quantity of active soil microbes – fungi and bacteria- can be represented by actual living carbon associated with “respiring (live) cells producing CO2 within a soil systems” – from Dr Haney and Brinton. This living microbial consortia is associated with many positive properties such as transforming chemicals, aiding pesticide degradation, facilitating the release of nitrogen from organic matter and contributing to soil aggregation. The latter property alone may account for more than 50% of soils ability to resist erosion.

ACTIVE not STATIC CARBON: Measuring microbial activity is not the same as determining total organic matter (SOM) or  total-C, both determined by combustion. “Those show the quantity but not the quality” of  the soil carbon. Woods End hopes that by making testing more streamlined and accessible, agronomists, farmers and soil scientists will be able to routinely include biological measures in explaining soil fertility.