Alfalfa seeding year management
Minnesota forage production, including alfalfa hay and haylage, dry hay, and corn silage, totaled more than 5.8 million acres (USDA–NASS, 2014). Taking a closer look, there were more than 3 million tons of hay produced in Minnesota 2014. This level of production generated revenue from direct sales, not including animal utilization, of more than 1 billion dollars. It is important to note that the total revenue of hay forages was based on an average yield of only 2.3 tons per acre. If annual production increased by 10 percent, this relatively small increase of 0.2 tons per acre would equate to over 100 million in annual revenues.
During the past 60 years, alfalfa yields, forage quality, and persistence has been increased through a combination of improved genetics, disease and insect control and more intensive nutrient and harvest management. Even though there has been substantial work in improving the production of alfalfa, these technologies and research finding focus on the 1st through 3rd production years resulting in limited research associated with seeding year yield improvements.
Seeding year yields
In 1972, Tesar and Jackobs reported greater seeding year alfalfa yields in a 3–harvest system compared to a 2–harvest system. They also reported that under ideal situations, maximal seed year yield expectations were 40 to 60 percent of those from established alfalfa. In Minnesota, Sheaffer (1983) found that seeding year yield and nutrient concentrations were maximized by early May seedings with initial harvest 60 days later at bud stage with an additional 2 to 3 harvests per year. Brummer, et al. (2002) explored the potential for seeding year yield improvement by mixing seed of non-dormant alfalfa with more seeding year growth with conventionally dormant alfalfa varieties. However, their findings demonstrated that the inclusion of non-dormant seed with dormant alfalfas in the seeding year reduced yields in the year following seeding, because the non-dormant alfalfa died.
With today's modern varieties that are capable of yielding 6 to 7 tons per acre and alfalfa hay prices ranging from 195 to 295 dollars per ton (Dan Martens, Sauk Centre Hay Auction, 2015), there is incentive to develop management practices that not only improve seeding year management, but also optimize the total revenue stream. One potential area for optimization is improvement in seeding year yields. Current recommendations for seeding year management were designed to ensure enhanced persistence throughout the production years (Shaeffer, 1983).
Seeding year harvest studies
New, moderately dormant to semi–dormant alfalfa varieties are characterized as "very winter-hardy" to "winter-hardy." The increased fall and spring growth potential of the new semi–dormant winter-hardy alfalfa varieties provide opportunities for the development of new management strategies that could increase yield in the seeding year without hampering persistence and yield in production years. Our objectives were to evaluate effects of seeding year harvest regimes on forage yield, quality, and persistence of new moderate to semi–dormant alfalfa varieties.
In spring of 2014, six alfalfa varieties (four from Alforex Seed, and two from Pioneer) with fall dormancies ranging from 2 to 5 were direct–seeded at three Research and Outreach Centers (Rosemount, Becker, and St. Paul, MN). The alfalfa varieties were subjected to three different seeding year cutting management strategies of increasing harvest intensities:
- Standard 2–cut system where alfalfa was harvested 60 and 105 days after planting (DAP)
- Improved quality 2–cut where alfalfa was harvested 60 and 90 DAP
- Increased yield 3–cut system where alfalfa was harvested 60, 90 and 135 DAP. The final harvest occurred in fall (i.e. early October)
Forage yield (dry matter) and quality was assessed for each of the harvest intervals. The newly seeded alfalfa was kept weed–free by using post emergent broadleaf and grass herbicides
Averaged across the three locations, yield did not differ across the six alfalfa varieties (Figure 1). Alfalfa yields for both 2–cut systems for all six alfalfa varieties ranged from 0.9 to 4.0 tons per acre, whereas yields from the 3–cut system ranged from 1.5 to 5 tons per acre. The yield from alfalfa varieties was similar for both of the 2–cut systems; Not surprisingly, the 3–cut system outyielded both of the 2–cut systems by nearly 1 ton per acre.
Although forage quality was also similar across alfalfa varieties, cutting treatments did influence NDFd (Figure 2). Crude protein was similar across both alfalfa varieties and cutting treatments and ranged from 22 to 24 percent. The alfalfa varieties in the 'Improved Quality 2–cut' regimen with cutting 90 days after planting had increased NDFd values when compared to the 'Standard 2–cut' and the 3–cut system. Along with increased NDFd observed in the 'Improved Quality 2–cut,' the alfalfa variety CW FD2, the most dormant variety in the study, had the highest NDFd. This is not surprising, since maturation would have been slower (e.g. vegetative to bud) in the CW FD2 variety when compared to the other alfalfa varieties (e.g. bud to early flower), thereby increasing the quality.
Figure 1. Seeding year alfalfa yield as influenced by alfalfa varieties and cutting management. Error bars indicate ± 1 standard error, which is the estimated deviation from the mean.
Figure 2. Seeding year alfalfa NDFd as influenced by alfalfa varieties and cutting management. Error bars indicate ± 1 standard error, which is the estimated deviation from the mean.
A cutting system with a fall cut greatly improved the total season year yields; however, the fall harvest did reduce first cut yields (1.28 ton/acre) in the year following seeding by 3 percent when compared to the 2–cut systems (1.38 ton/acre). Even though cutting treatments did impact harvest yields, the six alfalfa varieties did not differ in yield. The analysis of forage quality is not yet complete. This study is ongoing with two additional high–intensity cutting systems and results will be reported as they are completed.
Brummer, E.C., K.J. Moore, and N.C. Bjork. 2002. Agronomic consequences of dormant - non-dormant alfalfa mixtures. Agron J. 94: 782-785.
National Alfalfa & Forage Alliance (NAFA). 2013. Winter survival, fall dormancy, and pest resistance ratings for alfalfa varieties. At https://www.alfalfa.org/pdf/2013%20NAFA%20Variety%20Leaflet.pdf
Sheaffer, C.C. 1983. Seeding year harvest management of alfalfa. Agron J. 1: 115-119.
Tesar, M.B. and J.A. Jackobs. 1972. Establishing the stand. p. 415-435 In C.M. Hansen (ed.) Alfalfa Science and Technology. Am. Soc. of Agron. Madison, WI.
USDA–NASS. 2014. State Agriculture Overview: Minnesota. At http://www.nass.usda.gov/Quick_Stats/Ag_Overview/stateOverview.php?state=MINNESOTA
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