Measurement of Forage

Another method used to estimate stocking rate is based upon direct measurement of the herbage produced. This method could be used as a demonstration project for a club tour or meeting.

This is a good place to differentiate between two range terms that are often confused – forage and herbage. Forage consists of the plant parts that are actually eaten by livestock and/or wildlife. Herbage includes all of the current year’s growth of plant material, whether used by livestock or not.

Mark off a circle, using a 20-inch piece of wire with a large nail in each end. Clip the herbage within this circle at ground level and weigh it. The herbage weight will be in pounds. Multiply the weight by 5,000, as there are 5,000 of these small plots in 1 acre. For example, if you had ¼ pound, you would have 1,250 pounds of herbage per acre – (¼ x 5,000 = 1,250). Clipped herbage should be air dried to assure the best estimate of actual herbage production.

To find out how long a cow could graze 1 acre that had 1,250 pounds of forage, multiply by ½, which would be 625 pounds. (Grazing half and leaving half is a guide to proper use of grass forage. It may be necessary to modify this guide, depending on kind of stock, kind of grass, season of use and soil-moisture relationships.) Say that the mature cow needs 30 pounds of grass (dry weight) a day; 625 divided by 30 equals 21, the number of days a cow could graze on 1 acre. Stocking on a year-long basis, you would need 17.3 acres for the cow (365 days divided by 21 equals 17.3 acres).

Regardless of how you determine the proper stocking rate for the range, watch the range carefully to see how the grazing affects the desirable range plants (‘green’ and ‘yellow’). Make adjustments in grazing plans from time to time until the greatest use of the range is made without serious damage to the important plants.