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United States Department of Agriculture

Agricultural Research Service

Title: Impact of Coal Combustion Product Amendments on Soil Quality: Ii. Mobilization of Soil Organic Carbon

Authors
item Stuczynski, Thomas - IUNG, POLAND
item MCCARTY, GREGORY
item Wright, Robert
item Reeves Iii, James

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 30, 1999
Publication Date: N/A

Interpretive Summary: The increasing production of coal combustion products has increased the need to find suitable uses of these products and there is evidence that with proper use, these products can be a valuable resource for soil amendment, but there is also concern that improper use can be detrimental to soil quality and the environment. More information is needed concerning the influence of combustion products on soil properties. From this, guidelines can then be developed on their use in both agricultural production and environmental reclamation. Two predominant products of coal-fired power plants are fly ash which is the particulate matter carried in the flue gas stream from the boiler, and bed ash which is produced by desulfurization technology involving addition of lime to coal before combustion in fluidized bed boilers. The studies reported showed that excessive application of bed ash caused substantial mobilization of soil organic C whereas fly ash had little influence on soil organic matter. This study indicates that soil quality can be influenced by application of combustion products but with proper use, soil organic matter can be conserved.

Technical Abstract: Previous work provided evidence that application of coal combustion products at rates exceeding liming requirements may cause considerable degradation of organic N in soils. To investigate the influence of such application rates on fate of soil organic matter, we studied the effects of different amounts (0, 20, 40, and 80 g/kg soil) of two products (bed ash and fly ash) on mobilization of organic C in soil. The studies showed tha whereas fly ash mobilized little or no organic C when applied at rates as high as 80 g/kg soil, bed ash caused substantial mobilization and loss of soil organic C when applied at the rate of 20 g kg soil. Chromatographic and spectroscopic methods were used to characterize the different forms of carbon mobilized in soil amended with combustion products. These studies showed that various forms of organic C were mobilized by bed ash treatments including carbohydrates, phenolic substances, humic substances, and amino acids. It was found that the total amounts of soil organic C mobilized by bed ash treatments were related to increased soil pH and with the losses of C associated with increase of soluble humic substances. The losses of organic C from soils treated with bed ash were found to be as high as 15.5% of the total soil organic C. These studies also provided evidence for stabilization of some forms of soil organic C by Ca from bed ash.

Last Modified: 9/10/2014
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