Submitted to: Rangelands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 17, 1995
Publication Date: N/A
Interpretive Summary: Grazing readiness or time to begin grazing cool-season grasses has generally been based on calendar date and not plant development stage. Since plant development is not the same each year using the calendar date can lead to grazing too early which will reduce plant vigor, stand density and forage production, and increase disease, weed, and insect infestation. Research was conducted of Mandan to determine the relationship between growing degree-days and the number of leaves formed on a grass plant. Results suggest that managers can determine the stage of grass development by calculating growing degree-days. Grazing readiness can then be based on the development stage of the grasses as determined from accumulated growing degree-days which removes the chances of grazing too early and causing damage to the plant resource base. This paper includes a simple method managers can use to record and calculate pasture readiness using temperatures reported in their daily newspaper. Using the growing degree- day approach will take the guesswork out of when the grazing season can begin. Basing grazing readiness on plant development stage of a few key grasses can be beneficial to the overall health of the grass stand.
Technical Abstract: Management decisions based on plant growth and development can be beneficial to the overall health of the grass stand. The time for starting spring grazing is critical to the season-long vigor and productivity of grasses. Pastures and range damaged by grazing too early may require several years of rest to regain productivity. Grazing readiness or time to obegin grazing has generally been based on calendar date. Beginning grazin based on a calendar date does not take into consideration plant development stage. Determining grazing readiness from the development of a few key grasses present in the pasture or rangeland can serve as a guideline for management decisions. Initiating grazing at a specific development stage is predictable and can be repeated each year, whereas initiating grazing at a specific forage yield is not as easily predictable and may be highly variable. In understanding plant development and in developing management criteria, it is important that scientists, action agency people, and producers use common terms in describing the development stages of forage crops. Accepting use of the development stage concept should provide a more detailed description of plant development events and be more effective for information transfer activities.