Integrating livestock and crop enterprises presents a competitive advantage for combo farms, says South Dakota State University Cow/Calf specialist Warren Rusche.
The advantage comes because increased acres of corn provide more residue for feed, yet the land cost is charged to the crop enterprise. Rusche says that makes crop residues less costly than summer pasture or harvested feed.
Crop residue grazing works extremely well for cows in mid-gestation, Rusche says. Because cows will select the higher quality husks, leaves, and any whole ears left in the field they should not require additional energy or protein supplementation as long as they are not forced to consume poor-quality portions of the plant, like the stalk.
Even cattle with greater nutrient requirements such as growing calves or replacement heifers will perform well grazing stalks when provided supplemental protein, he says.
While some farmers are concerned about the effects of grazing on next year's crop, Rusche cites recent University of Nebraska research that studied the effects of grazing corn stalks in the fall on soybean yields the next year in a no-till system over 10 years.
In those studies, soybeans planted after corn stalks were grazed in the fall yielded about three bushels more compared to ungrazed corn stalks. The same pattern was shown in a one-year comparison at the SDSU Southeast Research Farm, although those differences were not statistically significant, Rusche says.
Another common concern is that grazing stalks will remove too much residue and greatly affect soil organic matter. The long-term yield results from Nebraska would suggest that this has not been a significant problem in that system, Rusche says, but it is possible to estimate the quantity removed compared to the amount of residue produced.
For every bushel of corn, there is approximately 45 pounds of residue. The husks and leaves represent about 16 pounds of that total. If a 1400-pound cow consumes 2.5% of bodyweight per day, in thirty days she would eat about 1050 pounds of husks and leaves. However, not all of that organic matter leaves the field. Forty to fifty percent of the husks and leaves are indigestible, meaning that of the 1050 pounds consumed, about 400 pounds return to the field as manure for a net removal of 650 pounds.
A field that yields 150 bushels per acre will produce 6750 pounds of total residue. In that case, the 650 pounds removed represents only about 10% of the total. Keep in mind that if the field is not grazed or tilled, the husks and leaves are more likely to be blown into the ditch or fenceline.
"Residue grazing is an example of how integrating crops and livestock results in a 'win-win,'" Rusche says. "Corn stalk grazing represents an opportunity to cut feed costs for ranchers, or serve as a source of supplemental income for crop farmers, without hurting yields next year."