Recent experiments have shown that sulfofication or sulfuroxidation is an important process occurring in field soils. Plants have been found to require considerable amounts of sulfates for their best growth and inasmuch as sulfur is not present in soils in that form, but as unassimilable organic and inorganic compounds, the sulfur-feeding of crops will depend very largely upon the ability of a soil on which they grow to produce sulfates from these unavailable substances. In other words, the total sulfur content of a soil, alone, will not show the sulfur available for plant growth. The sulfofying power of the soil must also be ascertained.
Brown, P. E. and Johnson, H. W.
"Studies in sulfofication,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 3
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol3/iss34/1