Solvita Technology for Soil CO2 Respiration: Influence of Various Soil Factors.

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Soil CO2 respiration is an indicator of biological functioning, which relates to soil health.  Soil labs are increasingly performing soil biological tests including Solvita® technology, a method developed to enable commercial soil labs to readily gauge soil CO2 respiration.

Several factors influence the magnitude and quality of results for CO2 respiration. Chief among these are the pre-drying regime, plus moisture and temperature during the test. Soil labs in routine nutrient analysis do not normally control these factors. New factors that have emerged as exerting influence on respiration and which may be artifacts are the means of grinding and sieving soils before the test. Grinding and sieving to <1mm are routinely performed to obtain homogeneity for nutrient extraction but interact significantly with microbial response.

Closer investigations concerning optimal handling for respiration have found that soils which are unstructured due to various causes are extremely vulnerable to water over-saturation when moistened, resulting in a unnatural slump of respiration.  

Unstructured soil conditions may reflect actual field traits such as salinity and light texture or low organic content. Lab methods which cause destructuring of soil must be carefully examined. A method of watering to achieve 50% of water-filled pore space (WFPS) appears to compensate for unstructured soils’ tendencies to over-saturate and suppress respiration.  This session will discuss how soil biological testing may require special attention to soil handling to obtain consistent and reliable results.