The grazing options can be parameterized to remove defined fractions of aboveground live (FLGREM, graz.100) and standing dead (FDGREM, graz.100) plant material each month. The fractional returns of C (GFCRET, graz.100), N, P, and S (GRET(*), graz.100) are specified, having allowed for losses in animal carcasses and milk, transfer of dung and urine off the area being simulated, volatile losses of N from dung and urine patches, and leaching of N and S under urine patches. The proportion of N, P, and S returned in organic forms (FECF(*), graz.100) is also specified as is the lignin content of the feces (FECLIG, graz.100). As discussed in Grassland/Crop Submodel, grazing can have variable effects on plant production (GRZEFF, graz.100).
C returned to the system from feces and urine is accumulated annually in the crop/grass output variable CRETA.