Document: KAT-3-59-63

A nitrogen budget for Olmsted County, Minnesota.

BRADLEY, K.L.* 1, K.CRAWFORD 2 and J.M.H.KNOPS 1

University of Nebraska, Lincoln, NE 68588 1
Olmsted Soil and Water Conservation District, Rochester, MN 55901 2

Abstract:
Understanding nutrient sources, their sinks, and their outflows is important to maintain and improve soil fertility and crop yields, while reducing negative impacts on the surrounding environment. We developed a nitrogen budget for Olmsted County (1,700 km2) in southern Minnesota. Inputs include everything ranging from fertilizers (49%), legumes (30%), and atmospheric deposition (11%), to human foods (6%), stream flow (3%), and pet food (1%). The output data quantifies nutrient export in crops and animal products (47%), combustion NOx (25%), manure losses as NH3 (20%), stream flow (19%), and denitrification (10%). Total inputs amounted to 14,700 tons N/yr, and total outputs amounted to 9,900tons N/yr. Thirty-three percent of the inputs were unaccounted for in the output data, and possible sinks include the soil organic matter, groundwater, and/or increased atmospheric fluxes because of the uncertainty in the manure loss and denitrification estimates. These outflows still need to be investigated more thoroughly and quantified. This information could be used to test models or equations used to estimate values of inputs or outputs against the primary data and evaluate their accuracy.

Keywords: nitrogen cycling, regional nitrogen budget, agroecology

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This abstract is being presented at: 3:30 PM in session:
AGROECOLOGY