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United States Department of Agriculture

Agricultural Research Service

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Chemical Routines-in situ
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AnnAGNPS Pollutant Loading Model

A. Green BulletChemical Routines-in situ


A daily mass balance of nitrogen (N), phosphorus (P) and organic carbon (C) is computed for each cell (pesticides will be added later). Major components considered are uptake of N and P by plants, application of fertilizers, residue decomposition, and downward movement of nitrogen & phosphorus. The output from each cell includes sediment bound N, soluble N in runoff, sediment bound P, soluble P in runoff, and sediment bound organic carbon. Nitrogen and phosphorus are partitioned into organic and mineral parts and a separate mass balance computed for each. The nitrogen & organic carbon cycles represented in AnnAGNPS are simplifications that track only major nitrogen transformations of mineralization from humified soil organic matter and plant residues, crop residue decay, and fertilizer & plant uptake. Plant uptake of N & P are modeled through a simple crop growth stage index.

Contact :

Terrence Sobecki or William Merkel (chemical routines?in situ) or Joe Bagdon (pesticides only) or Frank Davis (pesticides only) or Rickey Bigler (in situ soils)

Last Modified: 8/12/2016
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