subroutine nut_orgn !! ~ ~ ~ PURPOSE ~ ~ ~ !! this subroutine calculates the amount of organic nitrogen removed in !! surface runoff !! ~ ~ ~ INCOMING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! enratio |none |enrichment ratio calculated for day in HRU !! erorgn(:) |none |organic N enrichment ratio, if left blank !! |the model will calculate for every event !! ihru |none |HRU number !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~ use organic_mineral_mass_module use hru_module, only : hru, sedorgn, sedyld, ihru, enratio use soil_module use plant_module implicit none integer :: j = 0 !none |HRU number real :: orgn_kgha = 0. !kg N/ha |amount of organic N in first soil layer real :: wt1 = 0. !kg/ha |weight of upper soil layer real :: er = 0. !none |enrichment ratio real :: frac = 0. ! |fraction of organic N in soil j = ihru !! HRU calculations orgn_kgha = soil1(j)%hsta(1)%n + soil1(j)%hact(1)%n !! kg/ha = t/m3 * mm * 10,000 m2/ha * m/1000 mm * 1000 kg/t wt1 = 10000. * soil(j)%phys(1)%bd * soil(j)%phys(1)%d if (hru(j)%hyd%erorgn > .001) then er = hru(j)%hyd%erorgn else er = enratio end if frac = orgn_kgha * er / wt1 !! HRU calculations !! kg/ha = t / ha * 1000. kg/t sedorgn(j) = 1000. * frac * sedyld(j) / hru(j)%area_ha !! update soil nitrogen pools only for HRU calculations if (orgn_kgha > 1.e-6) then soil1(j)%hact(1)%n = soil1(j)%hact(1)%n - sedorgn(j) * (soil1(j)%hact(1)%n / orgn_kgha) soil1(j)%hsta(1)%n = soil1(j)%hsta(1)%n - sedorgn(j) * (soil1(j)%hsta(1)%n / orgn_kgha) if (soil1(j)%hact(1)%n < 0.) then sedorgn(j) = sedorgn(j) + soil1(j)%hact(1)%n soil1(j)%hact(1)%n = 0. end if if (soil1(j)%hsta(1)%n < 0.) then sedorgn(j) = sedorgn(j) + soil1(j)%hsta(1)%n soil1(j)%hsta(1)%n = 0. end if end if return end subroutine nut_orgn