CO2 Field Test Estimator

Monitor Natural Microbial Respiration

The Solvita field test enables any person to monitor as-is or natural microbial respiration under circumstances unaffected by lab processing. To do this, one prepares a soil sample without drying or grinding. When measuring soil respiration in this way, the key factors which influence the outcome are moisture and temperature. Soils are often sampled at one temperature and then tested at another. In order to help calculate how these factors influence Solvita soil test results, Woods End offers a Solvita Calculator. The algorithm is based on the well-known Arrhenius Equation that relates biochemical reactions to temperature. We’ve modified it with soil moisture and a season-length factor.

Solvita offers two Calculators: Basic and Advanced.  The Advanced calculator allows you to adjust the recommendations by adding information about seasonal factors which are quite important. The calculator supplies an estimated CO2-C result and an estimated nitrogen mineralization that will occur over the course of your growing season given the temperature, moisture and season length which you input.

To Use the Calculator:

• Select your required unit of measurement (standard “Imperial” or metric)
• Enter your information: Solvita CO2 Color number, growing season length, and your average soil temperature for the growing season.
• Advanced Calculator: Additional soil properties can be input by clicking the “Show Advanced Calculator” button. This allows you to input available (soil-test) nitrogen and it will be subtracted from estimated crop requirement. If soil C:N is unknown the calculator assumes 12. Increase the C:N value if lots of crop stubble are present. You may use any suitable factor.

Notes to the Guide:

**Sequestered Carbon: this estimates the quantity of soil carbon associated with the measured level of field CO2 respiration rate. We’ve made some assumptions about the annual decay rate of carbon to make this useful.