ARS | Publication request: Putting numbers to rest, residue, and mob grazing

Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: May 12, 2011
Publication Date: June 1, 2011
Citation: Brink, G.E. 2011. Putting numbers to rest, residue, and mob grazing. Graze Magazine, June-July 2011. p. 10-11.

Technical Abstract: A grazier has little or no control over precipitation and soil type, and the ability to apply fertilizer and manure is limited by cost and availability. But one can control when, how often, and how much pastures are grazed. We conducted research in south-central Wisconsin to answer the following questions: 1) How does the post-grazing residue height of vegetative grass influence pasture growth? 2) How does mob-stocking of mature grass compare with traditional grazing of vegetative grass? 3) How is productivity affected by grazing grass that is relatively short and/or under potential stress during different times of the year? Question #1 was addressed by rotationally grazing each grass at 12 inches to 6-, 3- or 1.5-inch residues. Question #2 was answered by grazing each grass at a mature stage to approximately 6 inches residue, although some residue was trampled below this height. Question #3 was addressed by grazing when grasses were less than 6 inches tall to a 3-inch residual in the early spring when growth began (early May), in the summer when drought-stressed (late July), or in the fall (early October) before growth was halted by cold temperatures. Reducing residue height of vegetative grass reduced the amount of leaf area available for photosynthesis and slowed regrowth, which resulted in fewer grazing events and increased the average rotation time. While yield at each grazing event increased as residue height decreased, annual yield of all grasses was eventually reduced when residue height reached 1.5 inch due to the negative effect on regrowth. The primary effects of grazing mature grasses are to reduce the number of grazing events per year, increase the rotation time, and increase the yield at each event. The most harmful effect on pasture productivity was caused by grazing drought-stressed grass during the summer, as productivity was reduced when growing conditions improved in late summer and fall.