subroutine cbn_rsd_decomp !! ~ ~ ~ PURPOSE ~ ~ ~ !! this subroutine estimates daily nitrogen and phosphorus !! mineralization and immobilization considering fresh organic !! material (plant residue) and active and stable humus material !! ~ ~ ~ INCOMING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ihru |none |HRU number !! rsdco_pl(:) |none |plant residue decomposition coefficient. The !! |fraction of residue which will decompose in !! |a day assuming optimal moisture, !! |temperature, C:N ratio, and C:P ratio !!! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ OUTGOING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ LOCAL DEFINITIONS ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ SUBROUTINES/FUNCTIONS CALLED ~ ~ ~ !! Intrinsic: Max, Exp, Sqrt, Min, Abs !! ~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~ use septic_data_module use basin_module use organic_mineral_mass_module use hru_module, only : ihru, isep use soil_module use plant_module use plant_data_module use output_landscape_module, only : hnb_d implicit none integer :: j = 0 !none |HRU number integer :: k = 0 !none |counter (soil layer) real :: rmn1 = 0. !kg N/ha |amount of nitrogen moving from fresh organic ! |to nitrate(80%) and active organic(20%) ! |pools in layer real :: rmp = 0. ! |to labile(80%) and organic(20%) pools in layer real :: xx = 0. !varies |variable to hold intermediate calculation result real :: csf = 0. !none |combined temperature/soil water factor real :: cnr = 0. ! |carbon nitrogen ratio real :: cnrf = 0. ! |carbon nitrogen ratio factor real :: cpr = 0. ! |carbon phosphorus ratio real :: cprf = 0. ! |carbon phosphorus ratio factor real :: ca = 0. ! | real :: decr = 0. ! | real :: ipl = 0. ! |plant number in plant community real :: idp = 0. ! |plant number in plant data module real :: cdg = 0. !none |soil temperature factor real :: sut = 0. !none |soil water factor real :: nactfr = 0. !none |nitrogen active pool fraction. The fraction ! |of organic nitrogen in the active pool. j = ihru nactfr = .02 !zero transformations for summing layers hnb_d(j)%act_nit_n = 0. hnb_d(j)%org_lab_p = 0. hnb_d(j)%act_sta_n = 0. hnb_d(j)%denit = 0. hnb_d(j)%rsd_nitorg_n = 0. hnb_d(j)%rsd_laborg_p = 0. !! compute root and incorporated residue decomposition !! compute humus mineralization of organic soil pools do k = 1, soil(j)%nly do ipl = 1, pcom(j)%npl !! mineralization can occur only if temp above 0 deg if (soil(j)%phys(k)%tmp > 0.) then !! compute soil water factor sut = .1 + .9 * Sqrt(soil(j)%phys(k)%st / soil(j)%phys(k)%fc) sut = Max(.05, sut) !!compute soil temperature factor xx = soil(j)%phys(k)%tmp cdg = .9 * xx / (xx + Exp(9.93 - .312 * xx)) + .1 cdg = Max(.1, cdg) !! compute combined factor xx = cdg * sut if (xx < 0.) xx = 0. if (xx > 1.e6) xx = 1.e6 csf = Sqrt(xx) !! compute residue decomp and mineralization of !! fresh organic n and p (upper two layers only) rmn1 = 0. rmp = 0. if (soil1(j)%pl(ipl)%rsd(k)%n > 1.e-4) then cnr = soil1(j)%pl(ipl)%rsd(k)%c / soil1(j)%pl(ipl)%rsd(k)%n if (cnr > 500.) cnr = 500. cnrf = Exp(-.693 * (cnr - 25.) / 25.) else cnrf = 1. end if if (soil1(j)%pl(ipl)%rsd(k)%p > 1.e-4) then cpr = soil1(j)%pl(ipl)%rsd(k)%c / soil1(j)%pl(ipl)%rsd(k)%p if (cpr > 5000.) cpr = 5000. cprf = Exp(-.693 * (cpr - 200.) / 200.) else cprf = 1. end if ca = Min(cnrf, cprf, 1.) idp = pcom(j)%plcur(ipl)%idplt decr = pldb(idp)%rsdco_pl * ca * csf decr = Max(bsn_prm%decr_min, decr) decr = Min(decr, 1.) decomp = decr * soil1(j)%pl(ipl)%rsd(k) soil1(j)%pl(ipl)%rsd(k) = soil1(j)%pl(ipl)%rsd(k) - decomp ! The following if statements are to prevent runtime underflow errors with gfortran if (soil1(j)%pl(ipl)%rsd(k)%m < 1.e-10) soil1(j)%pl(ipl)%rsd(k)%m = 0.0 if (soil1(j)%pl(ipl)%rsd(k)%c < 1.e-10) soil1(j)%pl(ipl)%rsd(k)%c = 0.0 if (soil1(j)%pl(ipl)%rsd(k)%n < 1.e-10) soil1(j)%pl(ipl)%rsd(k)%n = 0.0 if (soil1(j)%pl(ipl)%rsd(k)%p < 1.e-10) soil1(j)%pl(ipl)%rsd(k)%p = 0.0 !! add mass and carbon to soil organic pools soil1(j)%meta(k)%m = soil1(j)%meta(k)%m + pldb(idp)%res_part_fracs%meta_frac * decomp%m soil1(j)%str(k)%m = soil1(j)%str(k)%m + pldb(idp)%res_part_fracs%str_frac * decomp%m soil1(j)%lig(k)%m = soil1(j)%lig(k)%m + pldb(idp)%res_part_fracs%lig_frac * decomp%m soil1(j)%meta(k)%c = soil1(j)%meta(k)%c + pldb(idp)%res_part_fracs%meta_frac * decomp%c soil1(j)%str(k)%c = soil1(j)%str(k)%c + pldb(idp)%res_part_fracs%str_frac * decomp%c soil1(j)%lig(k)%c = soil1(j)%lig(k)%c + pldb(idp)%res_part_fracs%lig_frac * decomp%c !! add nitrogen and phosphorus to soil organic pools - assume c/n and c/p ratios !! c/n=10 for metabolic and 150 for structural; c/p=100 for metabolic and 1500 for structural !! solve ntot = nmeta + nstr & nmet = 15.* nstr * cmet/cstr rsd_meta%n = decomp%n - soil1(j)%str(k)%c / (15. * soil1(j)%meta(k)%c) soil1(j)%meta(k)%n = soil1(j)%meta(k)%n + rsd_meta%n rsd_str%n = decomp%n - rsd_meta%n soil1(j)%str(k)%n = soil1(j)%str(k)%n + rsd_str%n soil1(j)%lig(k)%n = soil1(j)%lig(k)%n + lig_frac * rsd_str%n rsd_meta%p = decomp%p - soil1(j)%str(k)%c / (15. * soil1(j)%meta(k)%c) soil1(j)%meta(k)%p = soil1(j)%meta(k)%p + rsd_meta%p rsd_str%p = decomp%p - rsd_meta%p soil1(j)%str(k)%p = soil1(j)%str(k)%p + rsd_str%p soil1(j)%lig(k)%p = soil1(j)%lig(k)%p + lig_frac * rsd_str%p end if ! soil temp > 0 end do ! ipl = 1, pcom(j)%npl end do ! k = 1, soil(j)%nly return end subroutine cbn_rsd_decomp