!
!$Author: joelevin $
!$Date: 2011-03-24 11:33:26 -0500 (Thu, 24 Mar 2011) $
!$Revision: 11724 $
!$HeadURL: https://svn.weru.ksu.edu/weru/weps1/trunk/weps.src/src/lib_mproc/rootlay.for $
!
! This routine accepts the crop root depth, soil layer thicknesses,
! and the number of soil layers.  It returns the number of layers
! that will be considered to contain crop roots. 

      integer function rootlay (rtdepth, lthick, nlay)

      integer nlay
      real    rtdepth
      real    lthick(nlay)

      integer i
      real    d

      if ((rtdepth*1000.0) .lt. lthick(1)) then
        rootlay = 1
        goto 1000
	  endif
      d = lthick(1)
      do 100 i=2, nlay
        d = d + lthick(i)
        if ((rtdepth*1000.0) .lt. d) then
          if ((d-(rtdepth*1000.)).lt.((rtdepth*1000.)-                  &
     &        (d-lthick(i)))) then 
            rootlay = i
            goto 1000
          else
            rootlay = i-1
            goto 1000
          endif
        endif
        rootlay = nlay
  100 continue
 1000 return
      end