Soil Health and Yields on Non-Sodic Soils Amended with Flue Gas Desulfurization Gypsum

Flue gas desulfurization gypsum (FGDG) is approved for use in Kansas as a fertilizer and as a soil amendment. Gypsum is an effective product used in remediation of sodic soils. Marketing has promoted the general use of FGDG as a means of improving soil health, and this has prompted extension questions regarding whether or not FGDG would be beneficial for soil health when applied to non-sodic soils. Two 3-year studies were conducted in Kansas from 2013 to 2015 on long-term no-tilled fields; one was done with small research plots, and the other site was an on-farm collaboration with a producer and an agricultural retailer. No crop yield effects were observed for any of the site years. Soil SO4-S consistently increased with increasing FGDG at both sites. Electrical conductivity (EC) and Mehlich-3 P values were affected by the treatments on the small-plot study location, but not at the larger field study. The small-plot study location received less-than-average precipitation every year of the project, while the larger on-farm study location received above-average precipitation two out of 3 years, likely explaining the differences in EC at the two sites. There were no treatment differences at either site for the selected soil physical and biological indicators of soil health. Based on the results of this project, FGDG did not improve the health of two no-tilled, non-irrigated, non-sodic soils during a 3-year period, other than to supply SO4-S.