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Garden with Insight v1.0 Help: Soil patch next day functions: calculate mineralization of fresh organic P

Mineralization of fresh organic P is calculated using the decay rate constant derived for the mineralization of fresh organic N. Presumably these processes are so similar that one can use one set of equations to model both of them. Actually, the decay rate constant calculated for mineralization of fresh organic N uses a composite ratio of C:N and C:P and thus describes the state of both nitrogen and phosphorus in the soil. Mineralization of both N and P is at maximum when the C:N ratio is less than 25:1 or when the C:P ratio is less than 200:1. Widening of either of these ratios changes the rate of mineralization of both N and P. One could argue that this merging of mineralization rates for different materials is an oversimplification, but since the concentrations of these different ions may have impacts on both equilibria they may not be entirely separate either.

As with N, P mineralized from fresh organic P is divided into two portions. Eighty percent is released by the breakdown of the organic matter (the P the microbes don't need) and goes directly into the labile P compartment. Twenty percent represents phosphorus in dead microbial biomass and goes into the organic P compartment in the organic matter.

The decay rate constant is calculated even if fresh organic N mineralization is turned off, so calculation of fresh organic P mineralization does not rely on fresh organic N mineralization being turned on.

calculation of mineralization of fresh organic N
EPIC P Mineralization
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Updated: May 4, 1998. Questions/comments on site to
Copyright © 1998 Paul D. Fernhout & Cynthia F. Kurtz.