Forage legume species such as red or white clover, birdsfoot trefoil, and alfalfa are important plant contributors to productivity and quality of beef pastures in the Upper Midwest and elsewhere. Most notable among the many characteristics of forage legumes is their ability to fix nitrogen in a symbiotic partnership with the rhizobia bacteria that colonize root nodules of host legume plants. This partnership reduces the need for adding nitrogen fertilizer to pastures when legumes comprise 30 – 40% or more of the stand, reducing or eliminating need for nitrogen fertilizer applications.
Legumes provide many other benefits to pasture systems. Pastures that include legumes are more adaptable and productive in response to variable soil conditions, weather, insects/disease pests, weeds and other environmental stressors. For example, alfalfa, with its deep taproot, in combination with cool-season grasses, can provide increased pasture resiliency during dry summer periods.
Legumes help maintain more consistent forage quality and production for grazing animal diets over the season, and dilute the negative impacts of anti-quality and/or palatability factors of companion grasses such as endophytes in tall fescue. The net effect is that legumes can contribute significantly to improved beef production from pastures as shown in Table 1, summarized from two University of Wisconsin pasture research studies with stocker cattle at Lancaster and Arlington.
|Location/Years/Type of Cattle||Treatment||Average Daily Gain, pounds/day||Gain/Acre, pounds|
|Lancaster, 1998-2000, Holstein stocker steers1||Kura clover + grass||2.66||909|
|Red clover + grass||2.18||713|
|Arlington, 2010 – 2012, Beef crossbred stocker steers2||Grass (tall or meadow fescue) + nitrogen||1.85||607|
|Grass (tall or meadow fescue) + white clover||2.16||696|
1 Mourino, et al., 2003. Agronomy Journal 95:652-659.
2 Schaefer, et al., 2014. Agronomy Journal 106:1902-1910.
Legumes also provide other environmental benefits, serving as a pollen and nectar source for honeybees, and providing food and habitat benefits for other wildlife. Legumes have long been known for their contributions to improve soil quality and reduce erosion as part of a productive perennial cropland or pasture system on the landscape.
Managing for Legumes
Improving legume content of pastures need not be difficult. With a goal of 30 – 40% legume content, first determine which legume species are desirable for your location by consultation with local Extension or natural resources conservation staff. Consider that you may want different legume and grass species in mixtures across the farm, depending on soil variations and other production criteria.
Next, soil fertility needs should be assessed for pastures based on current soil tests and tailored for optimal forage legume production. For most Wisconsin pastures, legumes will express good growth when soil pH is at least 6.0 (or above). Liming also aids in addressing the higher calcium and magnesium requirements of legumes. Phosphorus levels should be at 15 ppm or higher (measured as Bray P1), and potassium levels should be maintained at 120 ppm (or above) for most Wisconsin legume-based pastures. Addition of other soil nutrients such as sulfur and boron may also be needed in some areas of the state to support good legume stands. Consult with your local Extension office for additional information on soil testing guidelines for pastures.
There are several methods for introducing legumes into pastures. Ideally, legumes are included in the seeding mix of newly established pastures, but frost seeding (broadcasting seed on frozen ground during late winter freeze/thaw events) and direct seeding with a no-till drill are also common methods of introducing legumes into established grass stands. Information on seeding rates, recommended varieties, agronomic and pasture management information for pastures is available at the UW Extension Team Forage and Grazing Resources websites: http://fyi.uwex.edu/forage/ and http://fyi.uwex.edu/grazres.
Results from pasture improvement and introduction of legumes will be most successfully realized under a managed grazing system. For beef producers, research suggests that a grazing system that includes multiple paddocks can provide management flexibility to optimize utilization of improved legume pastures and increase profits. Additional information on beef production topics is available at the Wisconsin Beef Information Center Pastures and Forages webpage: or through your local UW Extension office.