ARS | Publication request: FIELD EVALUATION OF FLUE GAS DESULFURIZATION RESIDUE AS A BORON AND SULFUR SOURCE FOR ALFALFA

Submitted to: International Ash Utilization Symposium
Publication Type: Proceedings
Publication Acceptance Date: October 20, 1997
Publication Date: N/A

Interpretive Summary: Flue gas desulfurization (FGD) residue is produced by limestone scrubbing of sulfur dioxide from the flue gases of coal-fired electrical generating stations. FGD residue can be an excellent source of boron and sulfur for plant growth. Many soils in the upper Midwest, which rely heavily on coal combustion for generating electricity, are deficient in boron. Application nof FGD residue to agricultural soils would supply essential nutrients to plants and reduce disposal costs of electrical utility companies. The objective of this study was to document the availability of FGD residue-borne boron and sulfur for alfalfa uptake when applied at agronomic rates to marginally B deficient soils. Modest amounts of FGD residue applied to alfalfa did not affect yields. FGD residue increased the boron and sulfur content of alfalfa plants relative to alfalfa grown on untreated soil. This effect was most pronounced late in the growing season. Hence, FGD residue can serve as a ready boron and sulfur source for alfalfa production, particularly later in the season when availability of native soil boron may become limiting. These results will be used by regulators, both federal and state, for development of sensible guidelines for agricultural utilization of FGD residues. The information is also useful to producers choosing boron and sulfur fertilizer options for their soils.

Technical Abstract: The flue gas desulfurization (FGD) residue produced by limestone scrubbing sulfur dioxide fron the flue gases of coal-fired electrical generating stations can be a source of some micronutrients essential for plant growth. The objective of this study was to document the availability of flue gas desulfurization (FGD) residue-borne boron (B) and sulfur (S) for alfalfa (Medicago sativa L.) uptake when applied at agronomic rates to marginally deficient soils. The FGD residue was applied at rates of 0, 0.46, and 3.74 Mg/ha on a silt loam soil immediately prior to alfalfa seeding. Alfalfa yields were unaffected by these rates of residue applications, but shoot B and S concentrations in the second and third cutting were increased by residue applications. Hence, FGD residue is a readily available B source. particularly later in the growing season when native soil B availability decreased. Residue-borne B did not leach below 0.15 m during the first year after application.