This variable will force the ratio of yield to total above-ground biomass to the specified value. If biomass is cut and removed (e.g., in hay cuttings), harv_idx must be used to specify the amount of biomass cut. For grain harvest, the harvest index in the plant growth database (plants.plt) is used instead of harv_idx, which assumes that only the seed is being harvested.

If the biomass is below harv_bm_min, the harvest operation will not be performed.

For grain harvest, the harvest efficiency defines the fraction of yield biomass removed by the harvesting equipment, with the remaining yield lost. For biomass harvest, if harv_eff is close to zero, the cutting or clipping are left on the ground and if harv_eff is 1.0, all cut biomass (yield) is removed. If the harvest efficiency is not set or 0.00 is entered, the model assumes the user wants to ignore harvest efficiency and sets the fraction to 1.00 so that the entire yield is removed from the HRU.

The name of the harvest operation is a primary key referenced when harvest operations are scheduled in management.sch or lum.dtl. All names in the harv.ops file must be unique.

The default harv.ops file includes the following harvest types:

This operation harvests the portion of the plant designated as yield and removes the yield from the HRU but allows the plant to continue growing.