Grazing harvested corn fields provides fall and winter management options for cattle producers and an income opportunity for landowners. Baling corn residue provides an opportunity for farmers to sell bales for feed or bedding. Feeding crop residues to cattle also contributes to sustainability by converting a byproduct into edible protein for people.
Either strategy removes nutrients and organic material from a field, though grazing recycles some nutrients and organic material in manure.
Grazing or baling practices could affect crop-management decisions and influence lease rates for stalk grazing or bale prices. University of Nebraska researchers reported on a series of studies evaluating the short- and long-term effects these practices have on crop production.
For the short term, the researchers conducted a two-year study to evaluate the impact of grazing on yields and nutrient removal from baling. The researchers compared three treatments at each of the five locations:
- Grazing residue, with a target of removing 50% of husk and leaf content, with stocking rates determined using the university’s Corn Stalk Grazing Calculator.
- Baling residue following harvest, with bales sampled and analyzed for nutrient content.
- No grazing or baling as a control.
Corn and soybean yields varied widely between sites, based on weather, soil types and management systems, the researchers note. Yields between treatments at each site, however, did not differ significantly.
The researchers did find a difference in residue cover following each of the treatments, with control fields averaging 88.7% cover, grazed fields averaging 77.5% and baled fields averaging 45.8%.
Baled fields had a slight numeric yield advantage over control fields. Researchers speculate baling might have resulted in better nitrogen availability in the short term and allowed the soil surface to warm up more quickly in the spring.
The amount of nutrients removed by baling residue varied between sites, but averaged 42 lb. of nitrogen per acre, 60 lb. of calcium expressed as CaCO3 equivalent and 4.3 lb. of phosphorus (P2O3). Potassium (K2O) removal varied widely, from 22 lb. to 285 lb. per acre.
The university researchers concluded grazing or baling corn residue provides a feed resource without negatively affecting subsequent crops. Baling does, in fact, remove some nutrients, but the amount varies widely. Farmers should weigh and sample bales to create an estimate of nutrient removal and future fertilizer requirements.
While short-term effects of grazing crop residue appear minimal or even beneficial, questions remain regarding longer-term effects on soil compaction, structural quality, organic matter content and nutrient cycling. To address these lingering questions, the University of Nebraska researchers also recently reported on a 16-year study evaluating the effects of grazing on no-till, irrigated land in a corn–soybean rotation in eastern Nebraska. They again compared three management systems:
- Fall grazing from November through January, with cattle stocked at 1.8 to 2.5 animal unit months (AUM) per acre.
- Spring grazing from February through mid-April, with cattle stocked at 2.3 to 3.1 AUM per acre.
- Control fields with no grazing.
Neither spring nor fall grazing had any significant effect on soil organic matter, although the researchers recorded a small increase in yield for both grazing systems compared with control plots. The researchers concluded that, under the conditions of this study, long-term corn-stubble grazing does not negatively affect soil structure, organic matter content or subsequent crop yields.