diff --git a/src/biogeophys/PhotosynthesisMod.F90 b/src/biogeophys/PhotosynthesisMod.F90
index a823bce548..b88fb170c7 100644
--- a/src/biogeophys/PhotosynthesisMod.F90
+++ b/src/biogeophys/PhotosynthesisMod.F90
@@ -172,6 +172,8 @@ module  PhotosynthesisMod
      real(r8), pointer, public  :: rc13_psnsun_patch (:)   ! patch C13O2/C12O2 in sunlit canopy psn flux
      real(r8), pointer, public  :: rc13_psnsha_patch (:)   ! patch C13O2/C12O2 in shaded canopy psn flux
 
+     real(r8), pointer, public  :: rc14_canair_patch (:)   ! patch C14O2/C12O2 in canopy air
+
      real(r8), pointer, public  :: psnsun_patch      (:)   ! patch sunlit leaf photosynthesis     (umol CO2/m**2/s)
      real(r8), pointer, public  :: psnsha_patch      (:)   ! patch shaded leaf photosynthesis     (umol CO2/m**2/s)
      real(r8), pointer, public  :: c13_psnsun_patch  (:)   ! patch c13 sunlit leaf photosynthesis (umol 13CO2/m**2/s)
@@ -346,6 +348,7 @@ subroutine InitAllocate(this, bounds)
     allocate(this%rc13_canair_patch (begp:endp))           ; this%rc13_canair_patch (:)   = nan
     allocate(this%rc13_psnsun_patch (begp:endp))           ; this%rc13_psnsun_patch (:)   = nan
     allocate(this%rc13_psnsha_patch (begp:endp))           ; this%rc13_psnsha_patch (:)   = nan
+    allocate(this%rc14_canair_patch (begp:endp))           ; this%rc14_canair_patch (:)   = nan
 
     allocate(this%cisun_z_patch     (begp:endp,1:nlevcan)) ; this%cisun_z_patch     (:,:) = nan
     allocate(this%cisha_z_patch     (begp:endp,1:nlevcan)) ; this%cisha_z_patch     (:,:) = nan
@@ -449,6 +452,7 @@ subroutine Clean(this)
     deallocate(this%rc13_canair_patch )
     deallocate(this%rc13_psnsun_patch )
     deallocate(this%rc13_psnsha_patch )
+    deallocate(this%rc14_canair_patch )
 
     deallocate(this%cisun_z_patch     )
     deallocate(this%cisha_z_patch     )
@@ -579,7 +583,7 @@ subroutine InitHistory(this, bounds)
        this%rc13_canair_patch(begp:endp) = spval
        call hist_addfld1d (fname='RC13_CANAIR', units='proportion', &
             avgflag='A', long_name='C13/C(12+13) for canopy air', &
-            ptr_patch=this%rc13_canair_patch, default='inactive')
+            ptr_patch=this%rc13_canair_patch, set_spec=spval, default='inactive')
 
        this%rc13_psnsun_patch(begp:endp) = spval
        call hist_addfld1d (fname='RC13_PSNSUN', units='proportion', &
@@ -592,6 +596,13 @@ subroutine InitHistory(this, bounds)
             ptr_patch=this%rc13_psnsha_patch, default='inactive')
     endif
 
+    if ( use_c14 ) then
+       this%rc14_canair_patch(begp:endp) = spval
+       call hist_addfld1d (fname='RC14_CANAIR', units='proportion', &
+            avgflag='A', long_name='C14/C(12+13) for canopy air', &
+            ptr_patch=this%rc14_canair_patch, set_spec=spval, default='inactive')
+    end if
+
     ! Canopy physiology
 
     if ( use_c13 ) then
@@ -1034,6 +1045,11 @@ subroutine Restart(this, bounds, ncid, flag)
             dim1name='pft', long_name='', units='', &
             interpinic_flag='interp', readvar=readvar, data=this%rc13_psnsha_patch)
     endif
+    if ( use_c14 ) then
+       call restartvar(ncid=ncid, flag=flag, varname='rc14_canair', xtype=ncd_double,  &
+            dim1name='pft', long_name='', units='', &
+            interpinic_flag='interp', readvar=readvar, data=this%rc14_canair_patch)
+    end if
 
     call restartvar(ncid=ncid, flag=flag, varname='GSSUN', xtype=ncd_double,  &
          dim1name='pft', dim2name='levcan', switchdim=.true., &
@@ -1173,10 +1189,13 @@ subroutine TimeStepInit (this, bounds)
             .or. lun%itype(l) == istice &
             .or. lun%itype(l) == istwet) then
           if (use_c13) then
-             this%rc13_canair_patch(p) = 0._r8
+             this%rc13_canair_patch(p) = spval
              this%rc13_psnsun_patch(p) = 0._r8
              this%rc13_psnsha_patch(p) = 0._r8
           end if
+          if (use_c14) then
+             this%rc14_canair_patch(p) = spval
+          end if
        end if
     end do
 
@@ -1197,11 +1216,15 @@ subroutine NewPatchInit (this, p)
     if ( use_c13 ) then
        this%alphapsnsun_patch(p) = 0._r8
        this%alphapsnsha_patch(p) = 0._r8
-       this%rc13_canair_patch(p) = 0._r8
+       this%rc13_canair_patch(p) = spval
        this%rc13_psnsun_patch(p) = 0._r8
        this%rc13_psnsha_patch(p) = 0._r8
     endif
 
+    if ( use_c14 ) then
+       this%rc14_canair_patch(p) = spval
+    end if
+
     this%psnsun_patch(p) = 0._r8
     this%psnsha_patch(p) = 0._r8
 
@@ -2072,6 +2095,7 @@ subroutine PhotosynthesisTotal (fn, filterp, &
          rc13_canair => photosyns_inst%rc13_canair_patch , & ! Output: [real(r8) (:) ]  C13O2/C12O2 in canopy air
          rc13_psnsun => photosyns_inst%rc13_psnsun_patch , & ! Output: [real(r8) (:) ]  C13O2/C12O2 in sunlit canopy psn flux
          rc13_psnsha => photosyns_inst%rc13_psnsha_patch , & ! Output: [real(r8) (:) ]  C13O2/C12O2 in shaded canopy psn flux
+         rc14_canair => photosyns_inst%rc14_canair_patch , & ! Output: [real(r8) (:) ]  C1342/C12O2 in canopy air
          alphapsnsun => photosyns_inst%alphapsnsun_patch , & ! Output: [real(r8) (:) ]  fractionation factor in sunlit canopy psn flux
          alphapsnsha => photosyns_inst%alphapsnsha_patch , & ! Output: [real(r8) (:) ]  fractionation factor in shaded canopy psn flux
          psnsun_wc   => photosyns_inst%psnsun_wc_patch   , & ! Output: [real(r8) (:) ]  Rubsico-limited sunlit leaf photosynthesis (umol CO2 /m**2/ s)
@@ -2142,6 +2166,8 @@ subroutine PhotosynthesisTotal (fn, filterp, &
                   sector_c14 = 3
                endif
 
+               rc14_canair(p) = rc14_atm(sector_c14)
+
                c14_psnsun(p) = rc14_atm(sector_c14) * psnsun(p)
                c14_psnsha(p) = rc14_atm(sector_c14) * psnsha(p)
             endif