Chemical 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:
Ron Bingner or
Fred Theurer.
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