NORTH DAKOTA ALFALFA PERFORMANCE TESTS IN 2006 The 2005-2006 winter at Fargo was very mild again with December (5.6 oF) and January (21.7 oF) above average temperatures. Snow cover was adequate whenever temperatures dropped significantly below normal. As a result little, if any, winter injury occurred on established varietal trials. Winter kill was a factor at Carrington where one replicate was discarded. Rainfall was 0.55 inches above normal for the alfalfa growing season (October 2005-September 2006). Rainfall during May to August was 3.55 inches below normal with no rain following the first week of June to the last week of July, which resulted in lower than normal second and third harvest yields. Rainfall during September 2006 was 1.73 inches above normal, which resulted in about average fourth harvest yields. Forage yield data for alfalfa cultivars and experimental lines tested at Fargo and Carrington, ND, in 2006 are presented in Tables 1 to 5. Insects and diseases were not considered a significant problem in 2006, none of experiments were treated for insects or diseases. Forage yields on established dryland stands at Fargo averaged from 5.7 to 6.0 tons/acre (Tables 1-3). This breaks the nearly 10 years of exceptional yields when forage yields ran 6.5 to 8.5 tons/acre. Forage yield of the first harvest was half of the seasonal forage yield due to stored soil moisture from the previous fall. Forage yields of FA-03 average 24.2 tons/acre for the four years of production (seeding plus three productive years) (Table 1). The highest yielding variety was Extreme at 3.6% greater than Vernal followed by 6400 HT at 2.7% greater than Vernal, but all varieties were considered equal yielding since the F-test for entries was non significant. Likewise, entries were not significantly different in FA-04 (Table 2) and FA-05 (Table 3). FA-04 and FA-05 had a traffic treatment applied on half of all plots. The traffic treatment was one pass with a medium-size tractor 5 days after harvest. Forage yields averaged 0.4 and 0.38 tons/acre less in FA-04 (Table 2) and FA-05 (Table 3), respectively, when the traffic treatment was applied. The reduction in yield from traffic in 2006 was much less than in 2005 when the forage yield was reduced 1.0 ton/acre with traffic (Table 2). The entry X traffic interaction was non significant in both experiments; yet, it is interesting to note that 4A421 was the highest yielding entry with traffic in both experiments. AmeriStand 403T was included as the traffic check since it has been shown in other states to be very tolerant to traffic, but these preliminary data do not show this traffic tolerance, especially in FA-04 (Table 2). Forage yield in the seeding year averaged 1.87 tons/acre (Table 4), which is substantially less than the last 10 years when seeding-year yields have average 3.56 tons/acre. The lower yield was anticipated with the limited moisture in 2006. The harvest date for the fourth harvest ranged from September 14 to October 20, which was when the alfalfa had initiate new growth from the crown. We have harvested the fourth harvest when the alfalfa reaches 40 to 50% bloom or regrowth is initiating (about 2 inches in height) for the past six years and have yet to cause significant winter kill on the stands. This is a real change in fall management that appears to be working. Irrigated forage yields at Carrington averaged 5.62 tons/acre with three harvests (Table 5), which is about 0.3 ton/acre less than normal during the first production year. The lower yield is probably due to some winter injury on the remaining plots after one replicate being tossed out due to winter kill. The 2006 North Dakota alfalfa hay crop was estimated November 15 at 2.08 million tons, down nearly 37% from 2005, by the North Dakota Agricultural Statistical Service. Per acre yield at 1.3 tons is down 35% from 2005. Alfalfa acreage was estimated at 1.6 million acres, down 3% from 2005. These data and previous years are available at http://www.ag.ndsu.nodak.edu/fargo/06data/index06.htm or http://www.ag.ndsu.nodak.edu/aginfo/variety/2005 or http://www.ag.ndsu.nodak.edu/plantsci/vtrial/vtrial.htm
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