Walker equation and nitrification

[David Radcliffe]

I am working on a nitrogen chain model. I am using the Walker equation for water content dependence for denitrification (ramps up as water content approaches saturation). I would like to use the Walker equation for nitrification. Is there a way to manipulate the equation parameters so that it ramps down at high water contents? Thanks.

[Jirka]

Walker's equation has been developed for the degradation of pesticides and can produce the following reduction functions.

Walker.png (22.97 KiB) Viewed 133 times

I think that it would be difficult to manipulate it to produce different shapes. J.

[Jirka]

Hi David,

I have looked at that again. If you select negative values for B, you can likely achieve what you want.

Walker1.png (30.38 KiB) Viewed 133 times

J.

[David Radcliffe]

Perfect! Thanks so much.

[David Radcliffe]

Oops, when I use a negative exponent I get an error:

"Floating Point Error! Calculation unstable.
Please check out input data..."

[Jirka]

The code was indeed working only for Walker equation with positive exponent (as designed). I copy below the computational module that can handle both cases (I do not think that PC-Progress will be updating version 2 of HYDRUS (2D/3D) when version 3 is already released).

J.

H2D_Calc.rar

(494.29 KiB) Downloaded 9 times

[David Radcliffe]

Thanks again.