– Stan Smith, OSU Extension PA, Fairfield County
Grazing corn crop residue can allow time for pastures to recover and be grazed again later.
Recently (Fastballs, Curveballs and Lessons Learned) I suggested that with 3.5 million acres of corn to harvest in Ohio this fall, for a spring calving cow herd the opportunity is great for extending the grazing season into fall and perhaps even early winter with corn crop residue. Now, as corn harvest approaches, let’s take a closer look at utilizing corn residue.
The opportunities afforded by grazing corn residue are primarily two-fold. Obviously, it offers a feed source at a time when the nutritional needs of spring calving, mature cows that have already weaned calves may be near the lowest of the year. Second is the ability to rest pastures and allow fall regrowth at a time when pastures may be the most stressed.
While corn residue offers a considerable amount of digestible energy and fiber, it’s always good to review the palatability and practicality of utilizing corn residue as a significant feed source. This is especially true as one considers the economics of baling and hauling the residue to the cows. Grazing is always the most economical option.
Corn crop residue is practical for feeding dry, gestating beef cows in mid gestation provided they have average or better body condition. Managed carefully, one acre of corn residue can yield up to 60 animal unit grazing days (60 days of grazing for a 1000 pound animal).
Grazing “efficiency” will determine exactly how much feed is realized from corn residue and how long an area can be grazed. Cows are selective grazers and will choose to eat the leaves, husks, loose kernels and dropped ears first. Moveable electric fencing can increase utilization up to 50% by controlling the amount of area grazed thus, limiting selective grazing. Strip grazing the cows will also reduce the potential for acidosis in situations where there may have been excessive field losses of grain. Simply dumping the cows onto the entire corn field will be least efficient but will allow more residue to remain on the field over the winter for cover, with the cobs and stalks being consumed last.
Fields containing corn residue should be grazed soon after harvest for optimum quality, and fields with poor drainage or compaction problems should not be grazed for extended periods of time. Producers with a Conservation Plan should check with NRCS to be certain the grazing of corn stalks does not violate the Plan.
If corn stalk fields are not presently fenced, temporary electric fencing is an economical alternative. Often times harvested corn fields can be encircled with a single strand of poly or high tensile wire supported with step-in posts for perhaps as little as $15 per acre. Even if a fence charger must be purchased to allow the grazing of corn residue, 30 or more days per acre of feed may be provided to a brood cow at a cost of under 50 cents/head per day. And, of course, the materials purchased to provide this temporary boundary may be reused from year to year, thus, making the “annual” cost of ownership even less.
When it comes to baling and transporting corn residues, consumption versus waste is a consideration worth pondering. The husk, leaf, and any kernels or whole ears in the bales will likely make up less than one third of each bale but will be readily consumed. If a bale processor is used, that might allow many of the stalks to become more palatable. However, if simply placing corn residue bales in bale rings, the abundance of corn stalks remaining after the more desirable parts of the bale are consumed will likely become bedding. If baled corn residue must be fed in bale rings, consider simply removing or pushing the chopper or spreader on the back of the combine forward and dropping the residue that comes through the thresher in a “windrow” and then bale only those windrows. The resulting bales will be a much higher percentage of the palatable portions of the corn residue.
As baling and transporting baled corn residue to the cows is considered, carefully evaluate the harvest and transportation costs involved on a “per consumable and digestible ton of dry matter” basis keeping in mind that a bale of crop residue seldom weighs the same as a similar size bale of hay.
As we evaluate the economics of harvesting and hauling corn residues, the fertilizer nutrient value being removed from the corn field and remaining in a pile at the bottom of a bale ring must also be considered. Estimating that each ton of baled corn stover removes with it 6 pounds of P2O5 and 32 pounds of K2O, there could easily be roughly $20 worth of P and K in each ton of corn residue hauled from a field.
The bottom line is simple . . . corn residue can be a valuable feed source for mature cows after the calves are weaned and before the end of gestation nears while also offering the opportunity to rest pastures. Whenever possible managed grazing is by far the best way to efficiently utilize corn residue.