Solvita and Other Measures as Indicators of Soil N Availability in Minnesota Soils

Abstract

Solvita is a commercialized short-term C mineralization test reported to predict potentially mineralizable N (PMN) and thus useful as a basis for N recommendations. Our study compared Solvita results with other measures of available N and potential corn yield, including PMN measured in a laboratory aerobic incubation, soil organic matter, KCl-extractable N, and permanganate oxidizable C. We showed that a 50% water-filled pore space wetting method gave much more reproducible results than the fixed volume method previously recommended. Solvita proved to be a good indicator of mineralizable C and N, but not better than SOM, inorganic N, or POXC in MN soils. Solvita had stronger relationships with these soil measures in coarser textured soils (clay < 35%) and was related to corn yield in corn-corn rotations but not when preceding crops were alfalfa or soybean. At this point, we do not recommend its use as a tool for N recommendations.