About 25% of Minnesota’s cropland acres are grasslands on which perennial grasses and legumes are grown. Grasslands are truly multifunctional, providing food and fiber for livestock and humans and multiple ecosystem services if properly managed. These ecosystem services include soil erosion control, water remediation, wildlife habitat, soil fertility improvement, and carbon sequestration. Grasslands have potential for new uses to meet evolving societal needs including cellulose production for conversion to biofuels, and carbon sequestration to mitigate atmospheric C increases. In addition, there is an increasing consumer demand for meat and dairy products from organic and grass-fed animals because of health benefits to both livestock and humans.
Grassland species in Minnesota that have been traditionally harvested as forage include cool season grasses and legumes. Traditionally-used cool season grasses include smooth bromegrass, orchardgrass, and timothy. Cool season legumes that are grown in pure stands or mixtures with grasses include alfalfa that is grown on over 1 million acres annually; red clover that is a replacement for alfalfa on acidic soils; and white clover that is used in pastures. Native warm season grasses that dominated the prairies prior to settlement are used primarily for restoration and conservation purposes. These include big bluestem, switchgrass, and Indiangrass, in addition to a diversity of perennial forbs.
Unfortunately, there has been a long-term trend for a decrease in grassland acreage. This trend is associated with a decline in diversified farms with livestock enterprises and the growth of acreage of annual crops like corn and soybean. However, in the coming years, we have an excellent opportunity to increase the grasslands in Minnesota. This will occur because of public concern about environmental degradation; increased costs of concentrate feeds fed in confinement livestock operations, and increased consumer awareness about the benefits of meat and milk produced from grasslands.
While there are many grassland species that have been used for production of livestock feed in grazing and harvested systems, we have an opportunity to improve several grassland species to enhance their value in multifunctional systems.
Meadow fescue is a perennial bunchgrass adapted to cool climates. On fertile soils it grows to 30 inches in height. It thrives in deep, rich soil, but also grows well on calcareous or sandy soils. In trials in other states, meadow fescue performs well and persists when it is rotationally grazed at a height of 8 to 10 inches. Our equine grazing research in Minnesota has shown it to be a palatable grass with uniform forage productivity throughout a May to October grazing season. There is a need to select for disease-resistant, winter hardy varieties that are adapted to rotational grazing systems and that perform well in mixtures with other grasses and legumes in Minnesota.
Perennial ryegrass is a cool season perennial grass used in cool, temperate climates throughout the world. It has many worthy attributes and is considered the best overall pasture grass for many areas. Ryegrasses, in general, grow best on fertile, well-drained soils, but perennial ryegrass can tolerate wet soils better than most other grasses. It does not generally tolerate drought or extended periods of extreme temperatures. Perennial ryegrass is known for its production of high quality forage especially late in the fall. In that capacity, it has great potential to extend the fall-grazing season when other cool season grasses become dormant. Despite its many attributes, perennial ryegrass use is limited by its susceptibility to diseases that reduce yield and forage quality and its lack of reliable winter hardiness. Specific plant breeding objectives involve selecting varieties for increased foliar disease resistance, increased winter hardiness, and increased forage yield under grazing/multiple cutting systems.
Alfalfa is the most widely grown perennial forage legume in Minnesota. Winter hardy, disease-resistant varieties have been developed. Alfalfa conducts biological nitrogen fixation that results in high yields of a protein-rich forage and nitrogen available for following annual crops in rotation. The major thrust of private plant breeding efforts for commercial markets has been the development of upright, rapid re-growing varieties that are suitable for intensive harvest management systems. We propose to increase the use of alfalfa through two approaches:
Novel biofuel alfalfas
Novel biofuel alfalfa varieties are being developed by USDA-ARS and University of Minnesota faculty. These alfalfa lines are capable of producing a high protein, leafy co-product for livestock feed and stems for biofuel processing. Typically, standard alfalfa varieties designed for producing high quality hay, are harvested 3-4 times during the growing season. This harvest regime requires frequent trips into the field, exposes cut forage to the weather, and is very detrimental to nesting wildlife. There is a need for increased selection for biofuel varieties that have leaf disease resistance, lodging resistant and that can be harvested less frequently than commercial alfalfas. Large scale seed production is needed to allow for field scale evaluation of these alfalfas.
Grazing tolerant alfalfas
Most alfalfa acreage is mechanically harvested for hay or silage. However, alfalfa has great potential for use in rotational grazing systems. Unfortunately, alfalfa selections that are currently marketed for grazing in Minnesota show no yield or persistence advantage over hay type alfalfas. Faculty at the USDA-ARS affiliated with the University of Minnesota have selected alfalfas for tolerance to frequent mechanical mowing under Minnesota conditions, but these have not been evaluated in grazing trials. Hence, there is an excellent opportunity to conduct selection to develop grazing tolerant alfalfas for use in rotational grazing systems.
Nancy Ehlke, Professor, Department of Agronomy and Plant Genetics
Craig Sheaffer, Professor, Department of Agronomy and Plant Genetics
M. Scott Wells, Assistant Professor, Department of Agronomy and Plant Genetics
Don Wyse, Professor, Department of Agronomy and Plant Genetics