How Mother Nature Hedges Her Bets

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the May 2021 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

Pasture plants are generally classified as decreasers, increasers and invaders. Decreaser species are the plants you want to see and your cattle prefer to eat, so they face the most grazing pressure. Increaser plants tend to thrive when the decreaser species are challenged by overgrazing, drought or other sub-optimal conditions. Invaders (weeds) proliferate when increasers and the remaining decreasers are so weakened by overgrazing or environmental extremes that they have a hard time competing for nutrients, water and sunlight. 
cattle grazing on healthy, green pastures
Healthy, productive pastures are dominated by decreasers. The composition of the decreaser community in healthy native rangelands was shaped by thousands of years of natural selection and environmental pressures. In tame pastures, humans take the wheel from Mother Nature as we seek to establish and maintain a stand of tame decreaser species that can be productive and long-lived in our particular soil and climate conditions. In both native and tame pastures, good grazing managers adjust stocking densities, grazing intensities, grazing and rest period length and frequency, etc. based on annual and seasonal variations in growing conditions to maintain pasture health and optimize long-term forage and animal productivity. Continue reading

Carrying or Grazing Capacity

Are you managing a new-to-you pasture and you need to determine how to stock it? Perhaps it has been recently purchased or rented, or you simply don’t trust the information provided on historical stocking rates.

The first principle of pasture management is to balance the available forage supply with livestock demand. Carrying capacity (also known as grazing capacity) is the amount of forage available for grazing animals in a specific pasture or field. A substantial amount of Canada’s rangeland is in some form of public ownership (e.g. grazing leases, forest grazing allotments) and has carrying capacity data available. With privately owned or recently acquired land however, there may not be any information on historical forage production and carrying capacity.

Carrying Capacity is defined as the average number of livestock and/or wildlife that may be sustained on a pasture that fits the management goals. Site characteristics, such as soil, water, plant, and topography of the pasture, can impact carrying capacity. Forage production and availability for grazing can also affect carrying capacity. Source: Society for Range Management, 1998.

Carrying capacity can be calculated using a variety of techniques. All of them depend more or less on trial and error as they are monitored and adjusted over time as the carrying capacity for an individual year varies from the long-term average for the pasture. The effectiveness of each method depends on the kind of grazing land, but a combination of methods is generally required. Continue reading