With fall grazing upon us, some areas of South Dakota have been blessed with plenty of precipitation this year and other areas are still experiencing drought conditions. Regardless of where your ranch is located, a rancher must be very careful when grazing the fall green up of cool season grasses.
Cool season grasses have two growing seasons (Figure 1). They grow in the spring and early summer and then get another growth spurt in the fall. Warm season grasses grow later in the season during the summer and late summer and do not get another green up in the fall of the year.
Extreme diligence must be taken not to overgraze during the fall green up of cool season grasses. During the fall green up, cool season grasses are storing their energy reserves to ensure health through the dormant season and vigor next spring when the growing season starts again (Figure 2).
Tremendous damage to cool season grasses can happen if they are overgrazed during the fall green up and they are unable to build those root reserves. The plant will have less vigor next spring and may die out completely during the dormant season.
Native cool season grasses should not be grazed shorter than 6 inches in plant height. Also, by leaving sufficient plant height into the dormant season the soil surface will be protected from erosion and snow capture during the winter is optimized.
Figure 1. Warm season and cool season growth curves. Source: South Dakota Grassland Coalition Healthy Grasslands.
Figure 2. Fall green up of cool season pasture in Tripp County.