We compared ALP Soil Lab proficiency results to our own for the same set of soils. The high correlation (p<0.001) indicates the labs are testing the same population.

Solvita is used by many commercial soil labs and several labs are now being tracked by independent test proficiency programs. Results so far are promising:  a comparison of Woods End’s control results and those reported by other labs shows a high degree of correlation (see Figure). “This means that other labs are basically reporting the same data that we are”, says Brinton, developer of Solvita. Proficiency data also indicate variance within each lab and between all labs. For 8 monitored labs the internal lab variance is running at 12% and between-lab variance at 22%. Solvita headquarters considers these results acceptable. Brinton says “we are in uncharted waters here since this may be the first time a biological CO2 procedure has been used by so many labs across various regions and time frames. – We don’t yet know what level of variance is normal for a purely biological result”.  The Solvita CO2 burst test has been incorporated into the USDA Soil Health Tool (SHT) which will soon be available from commercial soil labs. In that tool, the Solvita result is used to index other results for an overall health score.