Relatively large losses of magnesium from the soil in the long-term fertility trial plot at Riverside—during a 28-year period—were revealed by analysis of soil samples taken in 1927 and in 1955. The losses of magnesium increased with increase in amount of fertilizers and gypsum added to the soil.

The above progress report is based on Research Project No. 594.

Frank T. Bingham, Assistant Chemist, University of California, Riverside, conducted the study on the ratio of exchangeable potassium and magnesium that is referred to in the above article.