Alfalfa seeding year management
Minnesota forage production, including alfalfa hay and haylayge, dry hay, and corn silage totaled more than 5.8 million acres1. Taking a closer look, there was more than three million tons of hay produced in Minnesota 20141. This level of production generated revenue from direct sales, not including animal utilization, of more than one billion dollars1. It is important to note that the total revenue of hay forages was based on an average yield of only 2.3 ton per acre. If annual production increased by 10%, this relatively small increase of 0.2 ton per acre would equate to over 100 million dollars in annual revenues.
During the past 60 years, alfalfa yields, forage quality and persistence have 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.
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 an 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 years4.
New moderately dormant to semi-dormant alfalfa varieties are characterized as "very winter-hardy" to "winter-hardy"5. The increased fall and spring growth potential of the new semi-dormant winter-hardy alfalfa varieties provides opportunities for the development of new management strategies that could increase alfalfa yield in the seeding year while not 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; 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 managements of increasing harvest intensities: a) the 'Standard 2-Cut' system involved harvesting at 60 and 105 days after planting; b) 'Improved Quality 2-Cut'; and c) 'Increased Yield 3-Cut'; both harvested 60 and 90 days after planting, whereas the 'Increased Yield 3-Cut' was additionally harvested in the fall 135 days after planting (i.e. early October). Forage yield (dry matter) and quality was assessed for each of the harvest intervals. The newly seeded alfalfa was maintained 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 and 4.0 tons per acre, whereas yields from the 3-cut system ranged from 1.5 to 5.0 tons per acre. The yield from alfalfa varieties was similar for both of the 2-cut systems (Figure 1). Not surprisingly, the 3-cut system out-yielded both of the 2-cut systems by nearly 1 ton per acre (Figure 1).
Figure 1. Seeding year alfalfa yield as influenced by alfalfa varieties and cutting management. Error bars indicate ± 1 standard error, which is the estimate of deviation from the mean.
Although forage quality was also similar across alfalfa varieties, cutting treatments did influence NDF digestibility (NDFd). Crude protein was similar across both alfalfa varieties and cutting treatments and ranged from 22 to 24%. The alfalfa varieties in the 'Improved Quality 2-Cut (IQ2)' regiment with cutting at 90 days after planting had increased NDFd values when compared to the 'Standard 2-Cut' and the '3-cut system' (Figure 2). Along with the increased NDFd observed in the IQ2, 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' when compared to the other alfalfa varieties (e.g. bud to early flower) thereby increasing the quality.
A cutting system with a fall cut greatly improved the total season year yields; however, the fall harvest did reduce 1st cut yields (1.28 tons per acre) in the year following seeding by 3% when compared to the 2-cut systems (1.38 tons per acre). Even though cutting treatments did impact harvest yields, the six alfalfa varieties did not differ in yield among each other. The analysis of forage quality is not complete. We are continuing the study this year, and are adding two additional high-intensity cutting systems.
- USDA-NASS. 2014 State Agriculture Overview: Minnesota. (2014).
- Tesar, M.B. and Jackobs, J.A. In Alfalfa Science and Technology 15, 415-435. American Society of Agronomy (1972).
- Brummer, E.C., Moore, K.J., and Bjork, N.C. Agronomic consequences of dormant-nondormant alfalfa mixtures. Agron. J. 94, 782-785 (2002).
- Sheaffer, C.C. Seeding year harvest management of alfalfa. Agron. J. 1, 115-119 (1983).
- NAFA. Winter survival, fall dormancy, and pest resistance ratings for alfalfa varieties. (2013).