c
      subroutine npcy
c
c     + + + PURPOSE + + +
c     This subroutine is the master nutrient cycling subroutine.
c     calls NPMIN, NYNIT, NLCH, NMNIM, AND NDNIT for each soil
c     layer.
c
c     + + + KEWORDS + + +
c     nutrient cycling

c     + + + COMMON BLOCKS + + +
*$noereference
      include 'crop/cgrow.inc'
      include 'crop/cenvr.inc'
      include 'crop/cparm.inc'
      include 'crop/csoil.inc'
      include 'crop/chumus.inc'
      include 'crop/cfert.inc'
*$reference

c     + + + LOCAL VARIABLES + + +
      real xx
      integer j
c     + + + LOCAL VARIABLE DEFINITIONS + + +
c     ssfn - sum of N leached from each layer (kg/ha)
c     xx - depth to previous layer (m)
c
c     + + + SUBROUTINES CALLED + + +
c     npmin
c     nynit
c     nlch
c     nmnim
c     ndnit
c
c     + + + OUTPUT FORMATS + + +
c
c     + + + END OF SPECIFICATIONS + + +
c
      smr=0.
      shm=0.
      sim=0.
      sdn=0.
      smp=0.
      sip=0.
      tsfn=0.
      xx=0.
      do 5 j=1,ir
c        J1=LID(J)
c        J2=J1
c     calculate relative moisture content of each layer
c        SUT=ST(J)/(FC(J)+1.E-10)
         sut=.8
         if (sut.gt.1.) sut=1.
c     calculate mineral P transformations
         call npmin (j)
c        IF (J1.NE.LD1) GO TO 2
c        calculate leaching from the top layer
c        CALL NYNIT (RQ)
c        GO TO 3
c     calculate leaching from layers other than the top
c   2    CALL NLCH (RQ)
c   3    TSFN=TSFN+SSFN
c         IF (T(J).LE.0.) GO TO 5
c     calculate soil temperature factor for each layer
c         CDG=T(J)/(T(J)+20551.*EXP(-.312*T(J)))
          cdg=1.
c        IF (RZ.LT.XX) GO TO 4
c         if (rz.gt.xx) then
c      calculate organic N & P transformations in layers where there are roots
            call nmnim (j)
            shm=shm+hmn
            smr=smr+rmnr
            sim=sim+wim
            smp=smp+wmp
            sip=sip+wip
c         endif
c     calculate N denitrification
c   4    IF (ST(J1)/PO(J1).LT..9) GO TO 5
c        if (st(j)/po(j).gt..9) then
c           CALL NDNIT
c           SDN=SDN+WDN
c        endif
c         XX=Z(J)
    5 continue
      return
      end