Wisconsin research uncovers a few surprises
Wisconsin alfalfa haylage may be going into storage too dry, alfalfa yields may be higher than the government reports and the second year of a four-year alfalfa production schedule provides the highest yields.
Those are some of the observations that can be made so far from a four-year study of alfalfa yields on Wisconsin farms.
“Keep in mind that we’re only into this four years; there’s a lot of variation because of weather. But we’ve got one full cycle done,” explained Mike Rankin, the University of Wisconsin crops and soils Extension agent in charge of the study. He spoke at the recent Midwest Forage Association (MFA) Risk-Reduction Research Summit in St. Cloud, MN.
Called the Wisconsin Alfalfa Yield and Persistence Project, the study measures alfalfa yield and quality over the life of a stand, beginning with the first production year – the year after seeding. The research also hopes to quantify productivity declines as alfalfa stands age.
Forage from project fields was generally weighed with on-farm scales to measure yields over entire fields without holding up harvest. Volunteer growers came primarily from the eastern part of the state.
In 2007, six farmers volunteered a total of eight fields, allowing all the forage to be weighed and samples taken at each cutting. In 2008, six more farmers brought 10 more fields into the project, and, in 2009, another six growers contributed eight additional fields. In 2010, two new cooperators added six more fields as six fields were taken out of the study.
Fields were seeded starting in 2006 through 2009; 26 were spring-seeded and six were seeded in late summer at rates ranging from 12 to 20 lbs/acre. They varied in size from 5.2 to 194.8 acres and were cut from three to five times depending on the year. During 2010, more than 6,500 dry matter tons were harvested.
The results? “Even with only four years completed, there are some things that have come to the surface,” Rankin said.
“The first one is the percent dry matter of harvested forage. This is all chopped forage (the few bales harvested were taken out of this analysis), but virtually every year we’re around 50% dry matter – sometimes a little less. It’s much drier than many people would suggest should be going into a bunker silo.”
Most universities recommend a dry matter content of 35-40%.
Average alfalfa dry matter yields totaled 5 tons/acre in 2007, 4.4 in 2008, 4 in 2009 and back up to slightly more than 5 tons/acre last year.
“In all of the years, we had at least one field that exceeded 6 tons of dry matter per acre except for 2009, where the highest of all fields was 5.27 tons of dry matter.
“But we need to keep in mind that every year we have lower-yielding fields as well,” he told the crowd of growers, researchers and industry representatives.
At the same time, audience members asked why National Agricultural Statistics Service (NASS) numbers were generally lower – national alfalfa hay yields averaged around 3.34 tons/acre from 2005 to 2009. For 2010, yields averaged 3.44 tons/acre by NASS accounts.
“The alfalfa statistics are not reflective, we believe, of what people are actually getting, and part of that is how they (NASS) collect the numbers for our crop,” MFA President Beth Nelson said at the meeting. “But they are willing to sit down and talk to us about it.”
Going into the study, Rankin figured yields would be highest the first production year, but that didn’t happen. “On average, our second production year is about 112% of the first and then we drop to 101% the third production year compared to the first. That fourth production year we really drop off.”
In 2010, total-season yield averaged 4.9 tons/acre for 2009 seedings, 5.4 for 2008 seedings, 5.1 for 2007 seedings and 4.5 for 2006 seedings.
“A few years ago, a lot of people touted this whole concept of keeping alfalfa two years, plowing it up and keeping the rotation rolling. Certainly, at two years you’re very productive, and I would argue that third year you are still very productive, as productive as the first year in many cases.”
Rankin also observed that fifth-cut yields were always low – far less than 1 ton of dry matter per acre. “This study so far just confirmed my suspicion that it’s not smart to take a fifth cut in late fall. Just as we see in other research, what we gain here with this cutting we generally lose with first crop the next year. Unless forage supplies are short, it’s best to stay out of fields in October.”
Quality measurements showed that crude protein, over the entire study, ranged from average lows of 18.9% to highs of 22.2%. NDF remained relatively consistent across cuttings, averaging 37% to 45.5%.
NDF digestibility was greater during cool-season cuttings, dropping during warmer second and third cuttings, and ramping up by fourth, Rankin said. It ranged from 40.1% to 50.3%, on average, over the four years.
Relative forage quality (RFQ) over the season averaged 196 in 2007, 166 and 175 in 2008 and 2009, respectively, and 151 in 2010.
Forage quality over the four years, was “exceptional – maybe too good at the expense of yield,” he said.
“When I came here in 1988, the biggest problem with alfalfa systems was, very easily, that producers were not getting out and cutting early enough, especially that first crop.” But the pendulum now, Rankin said, “on some farms has swung almost too far. If we’re cutting 200 RFQ, we’re giving up a lot of dry matter yield when we could probably wait five to seven days and pick up a third to a half a ton of dry matter and still get pretty decent quality.”
Wisconsin growers interested in joining the study can reach Rankin at email@example.com.