Merge branch 'rgknox/lnd/fates-l2fr-info'(PR #7542)

FATES plant dynamically regulate fineroots in the presence of nutrient limitations.
However it is only appropriate to enable this regulation when the soil is not being supplemented with nutrients.
This set of changes makes it so that supplementation status is passed to fates prior to its daily dynamics call, which is ideal since supplementation status can change mid run.
Collaborators:

@sharma-bharat @glemieux @walkeranthonyp @dmricciuto

[non-BFB] Fates Only

Author: peterdschwartz

components/elm/src/external_models/fates

@@ -76,6 +76,7 @@ module ELMFatesInterfaceMod
    use elm_varctl        , only : fates_history_dimlevel
    use elm_varctl        , only : use_lch4
    use elm_varctl        , only : use_century_decomp
+   use elm_varctl        , only : carbon_only,carbonnitrogen_only,carbonphosphorus_only
    use elm_varcon        , only : tfrz
    use elm_varcon        , only : spval
    use elm_varcon        , only : denice
@@ -501,17 +502,6 @@ subroutine ELMFatesGlobals2()
            call set_fates_ctrlparms('decomp_method',cval='CTC')
         end if
 
-        ! ELM ALWAYS has nitrogen and phosphorus "on"
-        ! These may be in a non-limiting status (ie when supplements)
-        ! are added, but they are always allocated and cycled non-the less
-        ! FATES may want to interact differently with other models
-        ! that don't even have these arrays allocated.
-        ! FATES also checks that if NO3 is cycled in ELM, then
-        ! any plant affinity parameters are checked.
-
-        call set_fates_ctrlparms('nitrogen_spec',ival=1)
-        call set_fates_ctrlparms('phosphorus_spec',ival=1)
-        
         if(is_restart() .or. nsrest == nsrBranch) then
            pass_is_restart = 1
         else
@@ -1176,7 +1166,7 @@ subroutine dynamics_driv(this, bounds_clump, top_as_inst,          &
       integer  :: nlevsoil                 ! number of soil layers at the site
       integer  :: ier                      ! allocate status code
       real(r8) :: s_node, smp_node         ! local for relative water content and potential
-      
+      logical  :: nitr_suppl,phos_suppl    ! Is ELM currently supplementing N or P?
       real(r8), pointer :: lnfm24(:)       ! 24-hour averaged lightning data
       real(r8), pointer :: gdp_lf_col(:)          ! gdp data
 
@@ -1341,8 +1331,26 @@ subroutine dynamics_driv(this, bounds_clump, top_as_inst,          &
 
       ! Nutrient uptake fluxes have been accumulating with each short
       ! timestep, here, we unload them from the boundary condition
-      ! structures into the cohort structures.
-      call UnPackNutrientAquisitionBCs(this%fates(nc)%sites, this%fates(nc)%bc_in)
+      ! structures into the cohort structures.  We also tell
+      ! fates the current supplementation status (used for dynamic rooting)
+
+      if(carbon_only)then
+         nitr_suppl = .true.
+         phos_suppl = .true.
+      else
+         if(carbonnitrogen_only)then
+            phos_suppl = .true.
+         else
+            phos_suppl = .false.
+         end if
+         if(carbonphosphorus_only)then
+            nitr_suppl = .true.
+         else
+            nitr_suppl = .false.
+         end if
+      end if
+      
+      call UnPackNutrientAquisitionBCs(this%fates(nc)%sites, this%fates(nc)%bc_in, nitr_suppl, phos_suppl)
 
       ! Distribute any seeds from neighboring gridcells into the current gridcell
       ! Global seed availability array populated by WrapGlobalSeedDispersal call