c
c
      subroutine cut
     i                 (af,cutht,
     i                  dstand,dflat,
     i                  stand,
     i                  cropht,dstemht,
     i                  bflg)

c     + + + PURPOSE + + +
c     Process # 32 called from doproc.for
c
c     This subroutine performs the biomass manipulation of cutting
c     biomass.  The component (either crop or a biomass pool) removed
c     is determined by flag which is set before the call to this
c     subroutine.  The flag may contain any number of combinations
c     found below.
c
c     Flags (binary #'s actually)
c     0  - cut standing crop at cut height (1)
c     1  - cut decomp pool #1 1'st residue (2)
c     2  - cut decomp pool #2 2'nd residue (4)
c     3  - cut decomp pool #3 oldest residue(8)
c     Note that biomass for any of these pools that are cut is transfered
c     to the cooresponding flat pool.
c     In addition, cutht must be positive for this process, so root mass
c     and below ground biomass are not delt with.  Below ground biomass will
c     usually be dealt with using either remove or the transfer subroutine.
c
c     + + + KEYWORDS + + +
c     remove, biomass manipulation

*$noereference
      include 'p1werm.inc'
      include 's1layr.inc'
      include 'manage/harv.inc'
*$reference

c
c     + + + ARGUMENT DECLARATIONS + + +
c
      integer bflg
      real   af,cutht
      real   dstand(mnbpls),dflat(mnbpls)
      real   stand,dstemht(mnbpls)
      real   cropht
c
c     + + + ARGUMENT DEFINITIONS + + +
c
c     cropht    - current crop height (m)
c     af        - area fractio of biomass removed (rest is left as flat residue)
c     cutht     - the above ground height that a crop is cut to
c     dflat     - (decomp) surface biomass by age pool  (kg / m^2)
c     dstand    - (decomp) standing biomass by age pool (kg / m^2)
c     dstemht   - (decomp) biomass stem height by pool (m)
c     bflg      - flag indicating what to cut
c       1 - Crop is cut
c       2 - 1'st residue pool
c       4 - 2'nd residue pool
c       8 - 3'rd residue pool
c       Note that any combination of pools or crop may be used
c       A bit test is done on the binary number to see what to modify
c     stand     - standing crop biomass (kg / m^2)
c
c     + + + ACCESSED COMMON BLOCK VARIABLE DEFINITIONS + + +
c
c     mnbpls        - max number of decomposition pools (currently=3)
c
c     + + + PARAMETERS + + +
c
c     + + + LOCAL VARIABLES + + +
c
      integer  i
      real   flatmass,standmass
c
c     + + + LOCAL VARIABLE DEFINITIONS + + +
c
c     flatmass  - temporary flatmass pool (kg / m^2)
c     i         - loop variable for decomp pools (3 pools total)
c     standmass - temporary standing mass pool (kg / m^2)

c     + + + END SPECIFICATIONS + + +

      if (BTEST(bflg,1)) then
c       print *, 'Flag 1 is on'
c   This flag is set when there is a need to cut the
c   crop at a certain harvest height.
c       print *, 'cropht', cropht
c       print *, 'cutht', cutht
       if (cutht.lt.cropht) then
        flatmass = flatmass+af*
     &   stand*(1.0-(cutht/cropht))
        standmass = stand*(1.0-af*cutht/cropht)
        cropht = cutht
       else
c       print *, 'No crop biomass to cut'
       endif
      endif
c   Now need to check and see if we need to cut the decomp pools (1-3)
c   for each individual pool check to see if there is biomass above the
c   proposed cut height, if so, adjust the pool as necessary.
      do 40 i=2,mnbpls+1
       if (BTEST(bflg,i)) then
         if (cutht.lt.dstemht(i-1)) then
           dflat(i-1) = dflat(i-1)+af*dstand(i-1)*
     &               (1.0-af*cutht/dstemht(i-1))
          dstand(i-1) = dstand(i-1)*(1.0-af*cutht/dstemht(i-1))
          dstemht(i-1) = cutht
          if (dflat(i-1).lt.0.0) dflat(i-1)=0.0
          if (dstand(i-1).lt.0.0) dstand(i-1)=0.0
          if (dstemht(i-1).lt.0.0) dstemht(i-1)=0.0
         else
             print *, 'Nothing to cut in decomp pool',i-1
         endif
       endif
 40   continue

      end