~ ~ ~ PURPOSE ~ ~ ~
this subroutine computes p flux between the labile, active mineral
and stable mineral p pools.
this is the alternate phosphorus model described in Vadas and White (2010)
~ ~ ~ SUBROUTINES/FUNCTIONS CALLED ~ ~ ~
Intrinsic: Min
~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~
loop through soil layers in this HRU make sure that no zero or negative pool values come in Convert kg/ha to ppm so that it is more meaningful to compare between soil layers **Soluble - Active Transformations**
Dynamic PSP Ratio PSP = -0.045log (% clay) + 0.001(Solution P, mg kg-1) - 0.035(% Organic C) + 0.43 Limit PSP range Calculate smoothed PSP average Store PSP for tomrrows smoothing calculation **Dynamic Active/Soluble Transformation Coeff******
on day 1 just set to a value of zero days since P Application days since P deficit Calculate P balance P imbalance
Move P between the soluble and active pools based on Vadas et al., 2006
Net movement from soluble to active
Calculate Dynamic Coefficant
limit rate coeff from 0.05 to .5 helps on day 1 when a_days is zero
add a day to the imbalance counter
Net movement from Active to Soluble
Calculate Dynamic Coefficant
limit varc from 0.1 to 1
add a day to the imbalance counter
** Active - Stable Transformations **
Estimate active stable transformation rate coeff
original value was .0006
based on linear regression rate coeff = 0.005 @ 0% CaCo3 0.05 @ 20% CaCo3
Estimate active/stable pool ratio
Generated from sharpley 2003
Store todays ssp for tomarrows calculation
*** Account for Soil Water content, do not allow movement in dry soil****
range from 0-1 1 = field cap
If total P is greater than 10,000 mg/kg do not allow transformations at all
Allow P Transformations
Add water soluble P pool assume 1:5 ratio based on sharpley 2005 et al