You know how much residue is left on the field after you harvest a corn crop (you can probably look out the window and get a good idea), but did you know that the residue amounts to about half of the total crop weight? That’s right, 50% of the biomass you grew is still sitting on the field after harvest.
That corn residue can be used as a winter feed source for beef cattle, squeezing another use out of the crop and greatly cutting winter feed costs for combined operations. One acre of corn residue is about two months of feed for a 1,000 pound animal. Getting the most value out of the residue requires a little planning and some awareness of what can go wrong, however. It doesn’t save you any money if you end up with a beef herd with nitrate poisoning, or if the vet bills for foundered cows exceeds what you saved in feed.
To get the most out of the nutrition left on the field, animals should be allowed to graze immediately after harvest, as wind and rain quickly break down the nutritional quality of the residue. Cows can get about 65% total digestible nutrients, and about 7% of crude protein, from corn residue. Depending on the age and breed of the animals, you might need mineral supplementation to keep them healthy while they’re foraging on your corn fields.
Over the course of that 60-day feeding window, the cows will only eat about 20% of the residue – and you thought your kids were picky eaters! That’s actually good news, as it means that erosion and soil compaction will be greatly limited by the large amount of biomass that will be left on the ground. Compaction caused by hooves is usually limited – but just as with a tractor, wet soils will compact more and you might want to bring the herd back inside if the soil is damp, especially if you already have soil compaction issues on that field. Frozen ground is generally well-protected against compaction by animal hooves.
If you had a dry year, then the lower stalks (which comprise a large percentage of your residue biomass) are likely to be high in nitrates. That can cause nitrate poisoning in animals that feed on them – be careful about grazing on fields that suffered drought. Nitrate levels will break down over time, though, so you don’t usually need to worry about what happened in prior years. In addition, if there is grain on the field as well as corn, be sure that your cows get hay or other feed before they get at the grain to prevent foundering.
Not only does residue foraging save you money on feed costs, it also cuts your fertilizer bill for the next season. Cows like to eat, and eating has a natural consequence – and that 1,000 pound cow is going to drop about 63 pounds of “natural consequence” on your field every day. Be sure to take that additional fertilizer into consideration when designing your fertilizer strategy for next year.