!$Author$
!$Date$
!$Revision$
!$HeadURL$

!     This common block contains variables representing the crop
!     properties for each subregion from the last time the crop growth
!     routines were called. When the crop growth model is called
!     again these values represent the previous day. These are compared
!     to the state variables to determine any operations done on the
!     crop and the resetting of the crop state required to properly
!     simulate the crop response to the operation.

!     Parameter include files required:  p1werm.inc

!     + + + VARIABLE DECLARATIONS + + +
      real             prevstandstem(mnsub)
      real             prevstandleaf(mnsub)
      real             prevstandstore(mnsub)

      real             prevflatstem(mnsub)
      real             prevflatleaf(mnsub)
      real             prevflatstore(mnsub)

      real             prevmshoot(mnsub)
      real             prevmtotshoot(mnsub)
      real             prevbgstemz(mnsz,mnsub)

      real             prevrootstorez(mnsz,mnsub)
      real             prevrootfiberz(mnsz,mnsub)

      real             prevht(mnsub)
      real             prevzshoot(mnsub)
      real             prevstm(mnsub)
      real             prevrtd(mnsub)

      integer          prevdayap(mnsub)
      real             prevhucum(mnsub)
      real             prevrthucum(mnsub)

      real             prevgrainf(mnsub)
      real             prevchillucum(mnsub)
      real             prevliveleaf(mnsub)
      integer          prevdayspring(mnsub)

      common / prevstate /                                              &
     &           prevstandstem, prevstandleaf, prevstandstore,          &
     &           prevflatstem, prevflatleaf, prevflatstore,             &
     &           prevmshoot, prevmtotshoot, prevbgstemz,                &
     &           prevrootstorez, prevrootfiberz,                        &
     &           prevht, prevzshoot, prevstm, prevrtd,                  &
     &           prevdayap, prevhucum, prevrthucum,                     &
     &           prevgrainf, prevchillucum, prevliveleaf, prevdayspring

!     + + + VARIABLE DEFINITIONS + + +

!     prevstandstem - crop standing stem mass (kg/m^2)
!     prevstandleaf - crop standing leaf mass (kg/m^2)
!     prevstandstore - crop standing storage mass (kg/m^2)
!                    (head with seed, or vegetative head (cabbage, pineapple))

!     prevflatstem  - crop flat stem mass (kg/m^2)
!     prevflatleaf  - crop flat leaf mass (kg/m^2)
!     prevflatstore - crop flat storage mass (kg/m^2)

!     prevmshoot - mass of shoot growing from root storage biomass (kg/m^2)
!     prevmtotshoot - total mass of shoot growing from root storage biomass (kg/m^2)
!                     in the period from beginning to completion of emegence heat units
!     prevbgstemz - crop stem mass below soil surface by layer (kg/m^2)
!     prevrootstorez - crop root storage mass by soil layer (kg/m^2)
!                   (tubers (potatoes, carrots), extended leaf (onion), seeds (peanuts))
!     prevrootfiberz - crop root fibrous mass by soil layer (kg/m^2)

!     prevht  - Crop height (m)
!     prevzshoot - length of actively growing shoot from root biomass (m)
!     prevstm - Number of crop stems per unit area (#/m^2)
!            - It is computed by taking the tillering factor
!              times the plant population density.
!     prevrtd  - Crop root depth (m)

!     prevdayap - number of days of growth completed since crop planted
!     prevhucum - crop accumulated heat units
!     prevrthucum - crop accumulated heat units with no vernalization/photoperiod delay
!     prevgrainf - internally computed grain fraction of reproductive mass
!     prevchillucum - accumulated chilling units (days)
!     prevliveleaf - fraction of standing plant leaf which is living (transpiring)
!     prevdayspring - day of year in which a winter annual releases stored growth