All "cover crops" in SnapPlus are assumed to be unharvested, with all residue staying in the field. For harvested forage crops that provide over-winter cover, select an appropriate SnapPlus forage crop rather than a cover crop. Cover crops always follow a harvested crop (example: Corn silage to small grain cover crop) and overwintering forages always start in the fall of the crop year they will be harvested (example: Winter rye (forage) to Soybeans g+s, 15-20 inch row). Since cover crops are not harvested, they do not have recommendations for added nutrients and the SnapPlus nutrient balance calculations assume they do not remove P2O5 or K2O from the field.
Small grain cover crops: an over-wintering cover crop such as winter rye that is planted within about a week after the main crop harvest and is killed with tillage or herbicides the next spring prior to planting.
Annual cover crops: a cover crop such as oats that does not over-winter. An annual cover crop is typically planted within about a week after the main crop harvest and is killed by winter freezing.
Interseeded or aerial seeded cover crops are planted into the growing main crop without soil disturbance. Growth of the cover crop is "released" by harvest of the main crop. These types of cover crops over-winter and are killed by tillage or herbicides the next spring prior to planting.