There is a saying that you “take half and leave half” about grazing. However, with the weather events we’ve been seeing this past year, some producers are concerned about overgrazing.
Overgrazing doesn't just reduce grass production; it can reduce profits for years. While it may seem like you're getting every last bite from a pasture, overgrazing often leads to higher feed costs, lower carrying capacity, and more expensive pasture recovery over time.
Lower forage production means fewer grazing days. Producers may have to purchase hay or supplemental feed earlier than planned, and reduced carrying capacity can lower stocking rates in future years. It can also cause weeds or pest invasion, and soil erosion often increases. That can lead to additional management costs, and it can take three to five years to regain original carrying capacity.
For example, if overgrazing reduces forage production by 20%, a 100-acre pasture producing two tons of forage per acre loses the equivalent of 40 tons of forage. From this, we have calculated the original forage supply of 128.2 AUM.
We also assume 25% efficiency here, as some of the grass will be trampled and lost due to other natural phenomena. Now we reduce that by 20% to get the current carrying capacity of the field, and that is:
The average forage supply for this pasture is 128.2 AUM. With a 20% reduction from overgrazing, the current forage supply drops to 102.56 AUM. Subtracting the current supply from the average supply, 128.2 AUM minus 102.56 AUM, leaves a shortfall of 25.641 AUM for the season. This is called the grazing balance. Replacing that forage with purchased hay can quickly add thousands of dollars in feed costs.
The best option to avoid overgrazing is to be proactive. Some things producers can do are:
- Rotate livestock before plants are grazed too short.
- Monitor forage availability throughout the season.
- Adjust stocking rates during the season as needed.
- Leave adequate residual forage after grazing.
- Think of pasture as an investment that requires annual maintenance.
The cheapest forage you'll feed is the grass already growing in your pasture. Protecting that resource through proper grazing management can improve profitability today and preserve productivity for years to come.
References:
Aljoe, H. (2021). Critical management strategies for dormant season grazing during and following drought. Noble Research Institute.https://www.noble.org/regenerative-agriculture/drought/critical-management-strategies-for-dormant-season-grazing-during-and-following-drought/
Farm Progress. (2017, November 14). Range specialists warn overgrazing pastures and invasive plants reduce profitability. Farm Progress. https://www.farmprogress.com/livestock/range-specialists-warn-overgrazing-pastures-and-invasive-plants-reduce-profitability
Schacht, W. H., Volesky, J. D., Bauer, D. E., & Stephenson, M. B. (2011). Grazing systems for Nebraska Sandhills rangeland (EC127). University of Nebraska–Lincoln Extension. https://extensionpubs.unl.edu/publication/ec127/grazing-systems-for-nebraska-sandhills-rangeland
Benjamin, R. (2023, February 1). How much pasture do I need and what are AUMs? Nebraska Extension. https://beef.unl.edu/beefwatch/2023/how-much-pasture-do-i-need-and-what-are-aums/
South Dakota State University Extension. (n.d.). Grazing calculator. South Dakota State University Extension. https://extension.sdstate.edu/grazing-calculator
