2.1 KiB
2.18.7. Calculation of N uptake streams from active uptake and fixation¶
Once the final \(C_{nuptake}\) is known, the fluxes of C to the individual pools can be derived as
\[C_{nuptake,x} = C_{frac,x}.C_{nuptake}\]
\[N_{uptake,x} = \frac{C_{nuptake}}{N_{cost}}\]
Following this, we determine whether the extraction estimates exceed the pool size for each source of N. Where \(N_{active,no3} + N_{nonmyc,no3} > N_{avail,no3}\), we calculate the unmet uptake, \(N_{unmet,no3}\)
\[N_{unmet,no3} = N_{active,no3} + N_{nonmyc,no3} - N_{avail,no3}\]
then modify both fluxes to account
\[N_{active,no3} = N_{active,no3} + N_{unmet,no3}.\frac{N_{active,no3}}{N_{active,no3}+N_{nonmyc,no3}}\]
\[N_{nonmyc,no3} = N_{nonmyc,no3} + N_{unmet,no3}.\frac{N_{nonmyc,no3}}{N_{active,no3}+N_{nonmyc,no3}}\]
and similarly, for NH4, where \(N_{active,nh4} + N_{nonmyc,nh4} > N_{avail,nh4}\), we calculate the unmet uptake, \(N_{unmet,no3}\)
\[N_{unmet,nh4} = N_{active,nh4} + N_{nonmyc,nh4} - N_{avail,nh4}\]
then modify both fluxes to account
\[N_{active,nh4} = N_{active,nh4} + N_{unmet,nh4}.\frac{N_{active,nh4}}{N_{active,nh4}+N_{nonmyc,nh4}}\]
\[N_{nonmyc,nh4} = N_{nonmyc,nh4} + N_{unmet,nh4}.\frac{N_{nonmyc,nh4}}{N_{active,nh4}+N_{nonmyc,nh4}}\]
and then update the C spent to account for hte new lower N acquisition in that layer/pool.
\[\begin{split}C_{active,nh4} = N_{active,nh4}.N_{cost,active,nh4}\\ C_{active,no3} = N_{active,no3}.N_{cost,active,no3}\\ C_{nonmyc,no3} = N_{nonmyc,no3}.N_{cost,nonmyc,no3}\\ C_{nonmyc,no3} = N_{nonmyc,no3}.N_{cost,nonmyc,no3}\\\end{split}\]
Following this, we determine how much carbon is accounted for for each soil layer.
\[C_{accounted,x,j} = C_{spent,j,x} - (N_{acquired,j,x}.CN_{plant}.(1.0+ gr_{frac}))\]