Grass-legume mixtures are superior to monoculture grass or legumes in terms of productivity, quality, and net economic returns, based on our three years of observations after establishment.
In addition, there are numerous unquantifiable environmental benefits associated with grass-legume mixtures. Overall, a mixture of 50-50 percent grass-legume performed well and produced the highest economic net returns (Table 1). This bulletin compares the net economic return of nitrogen (N)-fertilized monoculture grass, monoculture legume, and a 50-50 percent grass-legume mixture in hay production systems in Wyoming.
Five treatments with varying seeding ratios of two grasses (meadow bromegrass and orchardgrass) and one legume (alfalfa) were tested during our study from 2011-2014 at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center (SAREC) near Lingle. The recommended seeding rates of alfalfa, meadow bromegrass, and orchardgrass at 20, 20, and 6 pounds pure live seed (PLS, refers to amount of live seed in bulk seed and is calculated multiplying seed purity percentage by seed germination percentage) per acre, respectively, were used.
Treatments included N-fertilized monoculture meadow bromegrass, N-fertilized monoculture orchardgrass, monoculture alfalfa, 50-50 percent alfalfa-meadow bromegrass, and 50-50 percent alfalfa-orchardgrass.
1Department of Plant Sciences
University of Wyoming, Laramie, WY
Regional Agronomy Specialist, Northeast Region
can maximize farm profits
Nitrogen fertilizer at 134 pounds per acre as urea was applied to only monoculture grass plots based on soil test results. All experimental treatments were repeated three times to precisely estimate the results.
Plots were established in 2011 and harvested three to four times each year from 2012 to 2014. Forage dry matter yield was recorded and forage quality was analyzed at each harvest.
A net return analysis approach was used in which the total cost was subtracted from total return during the study period to identify the most profitable treatment. The budget for production costs, inputs, and revenues for each treatment and year was calculated based on
actual operations at the study site. The prices for alfalfa, alfalfa-grass mixture, and grass hay were obtained from the USDA’s National Agricultural Statistics Service database. The unit price of hay was based on crude protein content.
There were variations among the treatments for the net return during the four-year study period. The 50-50 percent mixture of alfalfa-meadow bromegrass (Figure 1) provided the highest net return at $1,599 per acre, followed by the 50-50 percent mixture of alfalfa-orchardgrass at $1,383 per acre over the four-year period (Table 1). The 50-50 percent mixture of alfalfa-meadow bromegrass provided 45 and 212 percent more net
Figure 1. Plot with 50-50% mixture of alfalfa-meadow bromegrass at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center, Lingle.
economic return than monoculture alfalfa and meadow bromegrass, respectively. Similarly, the 50-50 percent mixture of alfalfa-orchardgrass provided 25 and 292 percent more net economic return than monoculture alfalfa and orchardgrass, respectively. The higher net economic return from grass-legume mixtures was primarily due to increased hay productivity (Table 1), even when accounting for a decreased value of hay on a per-unit basis when compared to the monoculture alfalfa system. Another reason for increased economic return from mixtures was due to the reduction in fertilizer and its application costs (compared to N-fertilized grass) and seed costs (compared to alfalfa) (Table 1).
The economic outcomes are:
Marschner, P., E. Kandeler, and B. Marschner. 2003. “Structure and function of the soil microbial community in a long term fertilizer experiment.” Soil Biology and Biochemistry. 35:453-461.
Sanderson, M. A., G. Brink, L. Ruth, and R. Stout. 2012. “Grass-legume mixtures suppress weeds during establishment better than monocultures.” Agronomy Journal. 104:36-42.
Smil, V. 2001. Enriching the earth: Fritz Haber, Carl Bosch, and the transformation of world food production. MIT Press, Cambridge, MA.
WAS (Wyoming Agricultural Statistics). 2017. United States Department of Agriculture, National Agricultural Statistics Service, Wyoming Field Office. p. 48.
Table 1. Four years total production costs, total return, and net return of different seeding ratios of grass-legume mixtures at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center near Lingle 2011 to 2014.
†ALF = Alfalfa; MB = Meadow bromegrass; OG = Orchardgrass.
‡N = Nitrogen applied at the rate of 134 pounds per acre as urea.
Importance of forage crops in Wyoming
Forage crops grown for hay production in Wyoming are very important for their economic contribution. According to Wyoming 2017 Agricultural Statistics, the total value of hay in 2016 was $137 million. The acreage of grass hay production in Wyoming is large – more than 50 percent of the total hay production acreage. The remaining is cultivated with alfalfa.
Monoculture grass hay production systems have been used for many years in Wyoming; however, these systems have several limitations. For example, grass hay production require heavy use of costly and energy-intensive nitrogenous fertilizers. The expenses associated with fertilizer, fuel, machinery, and labor increase cost of production and decrease net farm profit. Continuous use of chemical fertilizers can degrade the soil and environment if not used appropriately. The nutritive value of grass is low and is often supplemented with grain protein when fed to cattle and increases cost of cattle production.
Legumes have the ability to fix free atmospheric nitrogen. A grass-legume mixture may be a better option to reduce production costs, improve net economic return by improving productivity and quality of hay, and reduce soil and environmental degradation.
Issued in furtherance of extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Bret Hess, interim dean and director, College of Agriculture and Natural Resources, University of Wyoming Extension, University of Wyoming, Laramie, Wyoming 82071.
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