Tuesday, 8 November 2005
18

Tracing Dairy-Derived Dissolved Organic Carbon.

Jill C. Schlanser, Peter J. Hernes, and Thomas Harter. University of California Davis, Department of Land, Air, and Water Resources, One Shields Avenue, Davis, CA 95616-8628

DOC transport is a critical component of carbon sequestration models, both as a source term (transport of surface-derived DOC to depth within the soil column) and a loss term (transport via groundwater to rivers where it will eventually be respired). Large dairy operations in California's central valley generate a great deal of liquid manure which is frequently reapplied to forage crops. This study focuses on the quantity and composition of the dissolved organic matter (DOC) that is transported to groundwater from these operations, and how it is compositionally related to the liquid material applied at the soil surface. The background concentration of DOC in the region of the dairy farm is 4-6ppm, while concentrations in groundwater within the dairy range from just above background levels to as high as 75ppm. Within the wastewater settling ponds, DOC concentrations exceed 400ppm. The transport of organic carbon compounds throughout the phases of a typical dairy operation is examined with a focus on a relatively conservative organic compound, lignin. Lignin is commonly used as a source and diagenetic indicator of organic matter. Lignin phenol concentrations in the study site range between nearly 430ppb in settling ponds to over 10ppb in groundwater-draining canals. These concentrations range above and below the phenolic content of riverine systems, which contain an average of 26ppb lignin-derived phenols. Batch studies are being prepared to gain a better understanding of the potential fractionation of lignin-derived phenolic compounds between the solid and solution phases during transport of DOC through the soil column to groundwater. The results of this study will provide insight to the amount and state of carbon transported as DOC to groundwater from liquid manure fertilization, as well as refining the use of lignin phenols in organic matter characterization by describing any fractionation that may occur during transport.

Handout (.pdf format, 8347.0 kb)

Back to SOM, C Dynamics, and GHG Emissions: II
Back to S06 Soil & Water Management & Conservation

Back to The ASA-CSSA-SSSA International Annual Meetings (November 6-10, 2005)