Forage crops and pastures provide the bedrock to sustainable agriculture. Defined as the edible parts of plants, other than separated grain, that provide feed for grazing animals or that can be harvested for feeding (Allen et al. 2011), forages play an important role in Nebraska’s beef cattle industry while also enhancing crop diversity, wildlife habitat, and soil ecosystem services.
Among U.S. states, Nebraska ranks second in beef cow inventory, second in cattle on feed, and as recently as 2010, beef production accounted for over $10.7 billion of the $22.6 billion in economic revenue generated by agriculture in Nebraska. In the last ten years, however, there has been a dramatic conversion of grasslands to farmland in the western Corn Belt. Since 85 percent of all feed resources utilized to produce a pound of beef come from forage, the loss in grasslands may limit Nebraska’s beef production without efficient use of corn residues and cover crops as forage resources and adoption of strategies that increase productivity and efficient use of existing pasturelands.
The following projects discuss forage crop and pasture research at the University of Nebraska-Lincoln that is focused on developing management recommendations under this scenario while balancing considerations for efficiency of use and long-term sustainability of the natural resource.
Allen, V.G. et al. 2011. An international terminology for grazing lands and grazing animals. Grass and Forage Sci. 66:2-28.
Nitrogen cycling and use efficiency of ruminants grazing pastures with and without forage legumes
This study began in March 2010 to compare forage and animal production between fertilized smooth bromegrass pasture and smooth bromegrass-legume (alfalfa, red clover, and birdsfoot trefoil) pasture through 2014. The persistence of interseeded legumes also was monitored. The grazing trial began in May 2012 with 4 yearling cattle stocked at 11.5 AUM/ha in each of 6 pastures. Within each pasture, the cattle are rotated through 6 fenced paddocks with 4 to 6 day grazing periods. There are to be 5 cycles each year but there were only 4 cycles in 2012 because of drought and 4 cycles in 2013 and 2014 because of timing of precipitation. This project was led by Dr. Walt Schacht.
Cattle grazing diet composition effect on dung decomposition, soil nutrient movement, and CO2 Flux
This project was initiated in 2014 by Brad Schick, master's in agronomy student, to determine how dung excreted from cattle grazing legume-interseeded, nitrogen-fertilized, and unfertilized smooth bromegrass pastures affects dung chemical composition, dry matter decomposition, CO2 flux, and N availability in soil. Freshly deposited dung was collected by hand from the legume-interseeded, N-fertilized, and unfertilized treatments, refrigerated, separately homogenized, and placed as pats in a neighboring unfertilized pasture. Each treatment was collected 3, 7, and 30 days after placing the pats in two experimental periods (June and August) in 2014. Soil cores were taken directly below and laterally from dung pats to determine rate of nutrient movement through soil. CO2 flux from dung was measured for each treatment, as well as a non-dung influenced control. Dung collections coincided with vegetation and diet samples from rumenally-fistulated cattle to examine effects of the pasture treatments on nitrogen cycling through the plant-animal-dung-soil complex. Brad is co-advised by Dr. John Guretzky and Dr. Walt Schacht.
Establishment of binary perennial legume-annual warm-season grass mixtures
This experiment is evaluating effects of establishment of perennial legumes with an annual warm-season grass as a companion crop. The experiment was conducted at Lincoln, Nebraska in 2016. Whole-plots consisted of six legume species: alfalfa, birdsfoot trefoil, red clover, Illinois bundleflower, purple prairie clover, and roundhead lespedeza. Subplots consisted of four annual companion crop treatments: 1) none (negative control where weeds are not kept in check) and forage harvested in October; 2) none (positive control where weeds are pulled) and forage harvested in October; 3) sorghum-sudangrass seeded and where forage harvested is harvested twice in summer and again in October; and 4) sorghum-sudangrass seeded and where forage is harvested once in mid-summer and again in October. This research is being conducted by Martina La Vallie, a recent graduate from Augustana University, who is participating in a USDA-AFRI-ELI funded project entitled “Developing Research and Extension Skills of Students in Integrated Agronomic Systems” led by Dr. John Guretzky, Dr. Humberto Blanco, Dr. Roger Elmore, and Dr. Daren Redfearn. Dr. Guretzky is serving as Martina’s mentor during the fellowship.
Establishment of annual warm-season grasses in cool-season grass pastures
In 2015 and 2016, we conducted experiments at six locations to evaluate effects of no-till interseeding of annual warm-season grasses on forage accumulation in perennial cool-season grass pastures. Pastures consisted of smooth bromegrass at Mead, Nebraska, North Platte, Nebraska, and Manhattan, Kansas; crested wheatgrass at Sidney, Nebraska; tall fescue at Parsons, Kansas; and western wheatgrass pasture at Hays, Kansas. Treatments consisted of six annual warm-season grass treatments and two harvest frequency treatments. Warm-season grasses were interseeded after an initial harvest of cool-season grasses in spring and consisted of 1) sorghum-sudangrass; 2) sudangrass; 3) pearl millet; 4) corn; 5) forage sorghum; and a 6) non-seeded control. Harvest treatments were 1) once per year at 90 d after planting; and 2) twice per year at 45 and 90 d after planting. This project is led by Dr. John Guretzky.
Seeding rate effects on forage mass of sod-seeded sorghum-sudangrass
This experiment evaluated effects of seeding rates on establishment and forage mass of sorghum-sudangrass interseeded into existing sod consisting of tall fescue, Kentucky bluegrass, smooth bromegrass, white clover, and dandelion. The sod was mowed to a 1-inch stubble height before interseeding on 20 May 2016. This project is currently being conducted by Omar Muniz, an undergraduate student from the University of Texas El-Paso, who is participating in a USDA-AFRI-ELI funded project entitled “Developing Research and Extension Skills of Students in Integrated Agronomic Systems” led by Dr. John Guretzky, Dr. Humberto Blanco, Dr. Roger Elmore, and Dr. Daren Redfearn. Dr. Guretzky is serving as Omar’s mentor during the fellowship.