Assessing soil health in highbush blueberry with the Solvita^® CO₂ respiration test

Measurement of carbon dioxide release from microbial respiration in the soil is a potentially important tool to predict availability of mineralized nitrogen; a source of this essential element not measured in routine soil tests. A three-year field study assessed soil fertility and biological health in three organic highbush blueberry blocks (Vaccinium corymbosum L.) in New Jersey. Carbon dioxide production from the rhizosphere was measured with the Solvita^® CO₂ aerobic respiration test. Average annual CO₂ values from 2013-2015 for all six replicates 36.7 CO₂ ppm 40 g^-1 dried sample and averaging 3.08 on the Solvita^® 0-5 scale with 3.00 representing very good fertility and microbial activity. A survey of native forest soils with a wild blueberry understory had similar biological respiration measures averaging 3.29 on the rating system with an average carbon dioxide release of 41.2 ppm. Marginal ratings of 1.2 were measured for commercial, conventional blueberry soils that averaged only 6.08 CO₂ ppm. These biological measurements of microbial respiration differed by soil type in relationship to soil acidity, soil organic matter and the Lime Requirement Index. The Solvita^® system is a rapid, high-tech soil test that provided a simple, quantitative and inexpensive means to assess and compare an important indicator of soil health when changing farming practices over time.