Early season burning and grazing on subirrigated Sandhills meadows
by Tara Harms, Agronomy/Range science graduate research student at UNL
The Nebraska Sandhills are comprised of two unique major types of rangelands, upland range and subirrigated meadows. Subirrigated meadows make up about 10% of the land area of the Sandhills, with upland range making up the remainder. These meadows, while relatively small in land mass, are extremely productive and have immense value to Sandhills ranches. Meadows are used for hay production, grazing, or a combination of both.
Forage from meadows often becomes a critical feed source for livestock during the winter months. The sustainable use of subirrigated meadows for forage is important considering feed costs are often the single largest expense for a cow-calf producer.
The first project examined the use of prescribed early-season burning to remove excess standing dead vegetation and litter. In spring and early summer, water can often be found above or immediately below the soil surface on subirrigated meadows. Soggy conditions in some meadow areas can hinder haying or grazing. As a result, under-utilization of vegetation can lead to a buildup of standing dead plant material and litter. Under areas of heavy litter, soil temperature decreases, resulting in delayed growth of plants. Additionally, dead plant material harvested when haying can reduce forage quality later in the growing season. This research examined if prescribed burning early in the growing season to reduce standing dead plant material would reduce hay yields later in the summer.
Burning in late April to early May did not impact end of season hay production. Burned plots had similar hay production as non-burned control plots in mid-August. This suggests vegetation has sufficient time to fully recover following the prescribed burn. Early season grazing from early-May to early-June at approximately 50% utilization had the largest impact on end of season forage production. Grazing reduced end of season hay yields in all years compared with non-grazed controls. However, grazing did improve end of season crude protein of hay by 1 to 2 percent, likely due to reduced plant growth and more vegetative tillers. If the goal is to maximize end of season hay yield, spring grazing may not be the best option, but the tradeoff between early season grazing and later hay production may be worthwhile in some situations. Early spring grazing often provides a high quality forage to cattle before upland range green up. This defoliation can lead to better quality hay even though total yield may be reduced.
The second project addressed a common meadow management practice, late fall and winter grazing. Grazing regrowth on subirrigated meadows after upland range growth ceases has proven to be an economical way to extend the grazing season in the Nebraska Sandhills. However, little research has evaluated how grazing subirrigated meadow hay regrowth in the fall and winter impacted the following year hay production. Grazing before a hard frost may deplete plants’ carbohydrate reserves, which are used to initiate growth the following spring. This may in turn decrease hay production the growing season.
This study evaluated the effect of grazing pre-freeze and post-freeze on the next year’s hay production. The study consisted of four grazing treatments; late fall moderate intensity, late fall heavy intensity, winter heavy intensity, and winter moderate intensity. This project is currently in its second year. Hay production estimates were collected in July 2019 and data analysis will begin after the 2020 data collection to compare treatments to a non-grazed control to evaluate differences in hay production.
We hope this research benefits Sandhills ranchers by providing information that will help management to more efficiently utilize subirrigated meadows as a forage resource.
