By Cheryl Anderson
DTN Staff Reporter
OMAHA (DTN) -- When it comes to harvesting alfalfa, growers want to make sure they get every pound possible from their fields. Minimizing field traffic and getting hay off the ground as soon as possible are an alfalfa grower's best bets to ensure good yields in the next cutting.
Driving over fields too long after cutting can reduce yields in the next cutting, according to Dan Undersander, research and extension forage agronomist at the University of Wisconsin-Madison.
Tractors, balers, wagons and trucks can all break the re-growth of stems in the field, he said.
"The longer you wait after cutting, the worse the damage is after mowing," Undersander said. "As soon as you mow, the regrowth starts to come out. The bigger the plants are when you drive over them, the more stems you break off. And the more stems you break, the more you reduce the yield of the next cutting."
Undersander said UWM studies have shown when hay is cut and lying in the field, a producer loses 6% of dry matter from the next cutting for every day after mowing that someone drives over the field.
"If you get your hay up in two days, that's a 12% yield loss. If it's five days, then that's a 30% yield loss. That's huge," he said.
Undersander said he worked on a study that showed around harvest time, alfalfa grows about 150 pounds of dry matter per acre per day. So waiting five days can mean an extra 750 pounds of dry matter that is susceptible to traffic damage.
The general rule is to get the hay off the field as fast as possible to reduce the chance for traffic damage, but also to reduce the potential for other problems, including stunting regrowth by cover/shading it, insects underneath the windrows, and especially rain damage. Undersander cautioned that hay bales will soak up water from the ground when it rains; one of the reasons some growers are turning to wrapped bales.
"Some of the beef cattle people are going to wrapped bales because they can put it up wetter, they can preserve more quality, and it also helps them get the hay off the field faster so the yield is more," he said.
He added that he has done two studies looking at 10-foot versus 13-foot mowers, adding that most growers probably use larger mowers. Two swathes were merged into a windrow and harvested five days later. When using the 13-foot mower, the researchers got an extra half ton of yield for the year, simply because there was less wheel traffic on the field.
A wider swath enhances drying, spreading the alfalfa out more and helping it dry faster. Undersander said his recommendation is to make a wide swath for 24 hours, rake it out into a windrow to reduce the drying in the field by one day or more. That will improve the quality of the forage and increase the yield of the next cutting.
Undersander added that while a lot of growers use self-propelled mowers, they have to put alfalfa in a windrow between the two wheels, which slows drying time and quality is lost because of increased respiration of starches and sugars. Some large hay growers are now using triple mowers -- a mower in front of their tractor and on either side, giving them a wider swath. Then growers come in and merge it 24 hours later into a windrow and make the hay. Doing so helps retain higher quality hay so it's worth more on the market. It also helps the alfalfa dry faster as it's less likely to get rained on, he said.
"The principal is that everything we can do to get the hay off the field faster will increase the yield of the next cutting," he said.
Silage fields usually yield more than hay fields, he added, since haylage or silage is normally taken off the same day or the next day, whereas sometimes hay might not be taken off the field for three to six days.
PREVENTION OF TRAFFIC LOSSES
One way of minimizing damage to alfalfa stands from farm traffic is to plant alfalfa varieties labeled as "traffic tolerant." While it is unknown yet what exact characteristics this can be attributed to, it possibly may be that the crown is simply a bit deeper, that certain varieties have a little faster recovery time, or a number of other factors.
"All we know is that when we put traffic on different varieties, some show a great yield depression in the next cutting than other varieties do," he said.
Undersander suggested growers interested in exploring traffic tolerant varieties talk to their seed dealers.
Another suggestion is to use harvesting equipment with large capacity to reduce the percentage of the field that becomes covered with wheel tracks. Even though the equipment will have to be heavier, it will involve a smaller area. Undersander said this is one benefit of contract harvesters, because they usually have larger equipment.
"The idea here is that if you merge several swaths, maybe four or five, into a windrow, you drive the baler or chopper less over the field and cause less damage," he said. "Our engineers tell us this is the most efficient way to bale. It only takes about 15% more energy to bale twice as much."
Growers may also choose to make silage from higher-yielding fields, and make hay from lower-yielding fields.
"Silage fields yield more than hay fields because the traffic occurs very close to mowing, so there is very little regrowth and damage to the shoots," he said. "Haymaking occurs several days later so there is more damage to the shoots and greater reduction of regrowth."
OTHER TIPS
Undersander offered additional tips for reducing traffic on alfalfa fields:
-- mow and condition in a single operation.
-- use smaller tractors whenever possible.
-- avoid unnecessary trips across the field.
-- drive off field in as little distance as possible in loaded wagon/trucks.
-- collect dropped bales with the least driving possible and as soon as possible.
-- don't drive on alfalfa when harvesting adjacent fields.
-- don't use tractors with dual wheels.
Cheryl Anderson can be reached at Cheryl.anderson@dtn.com
Follow Cheryl Anderson on Twitter @CherylADTN
(CZ/BAS)
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