Leaf loss, field traffic topics at forage update

KIMBERLY – Because of how important leaves are for the quality, quantity, and feeding value of alfalfa hay and haylage, growers of the crop ought to give attention to how many leaves are being lost during harvesting.

That was one of the bits of advice that University of Wisconsin Extension Service agronomist and forage specialist Dan Undersander had for attendees at the 2017 series of agronomy updates. He pointed out that role or leaves in determining the quality of alfalfa is 71 percent — more than what the crop's maturity does at the time of harvest.

Leaf percentages

At the time of cutting, leaves should account for at least 45 percent of the forage mass, Undersander stated. He cited data from three states in 2015 which showed that up to 20 percentage points of the leaves were lost from the time of cutting to when the alfalfa was stored as haylage or in bales.

During 2016, an intern for Land O'Lakes monitored the fate of the leaves on alfalfa that had the suggested 45 percent of leaves at cutting, Undersander reported. By the time of chopping, that percentage had dropped to 32, representing a 16 percent loss on yield alone plus a drop in quality and potential for milk production.

“Every moving of the forage results in the leaf loss,” Undersander said. To minimize that loss, he recommends the use of rotary rakes and mergers and avoiding the use of tedders.

Instead of employing a tedder, place the cut alfalfa in wider windrows to quicken the drying, Undersander advised. When making baled hay, consider the use of a propionic acid in order to accommodate harvesting at a somewhat higher moisture.

If there's any doubt about leaf loss, check for fallen leaves before alfalfa is cut to determine if a different variety is more appropriate or if a fungicide treatment would have helped, Undersander continued.

Because of its role in causing leaf loss, don't use a flail conditioner, which is suitable only for cutting grasses, Undersander stated. Finally, realize that “a leaf cloud” arising from a chopper or the falling of fines from balers are other definite signs of leaf loss.

Traffic toll

Another common source of alfalfa yield loss is the field traffic that occurs three or more days after a field is cut, Undersander remarked. His research and observations are that field traffic causes a yield loss in the next crop (after the first cutting of the year) of six percent for every day after cutting when there is field traffic.

Among other concerns, it is not good practice to wait for several days to pick up round or square bales that have been dropped on a field, Undersander stressed. He said most of the damage is due to the breaking of the stems for the next cutting rather than soil compaction.

Equipment widths

Considerable research has been conducted on the correlation between field traffic during the harvesting cycle and the widths of equipment being used. The numbers are probably surprising to most people, he said.

With a 10-foot-wide cutterbar, the raking, chopping and the associated tractors, an equivalent of 145 percent of the field would be driven on. He said an increase to a 20-foot cutterbar would reduce that to 116 percent. For 13- and 26-foot widths, the equivalent field coverages for wheel traffic would be 110 and 88 percent.

In comparative studies of 10- and 13-foot wide cutterbars conducted in 2001, 2014 and 2016, the yield increases with the wider unit totaled 0.5 to 1 ton per acre for the second through fourth cuttings for the year, Undersander reported.

Flood effects

From the perspective of animals, there can be dire effects from eating forages harvested from alfalfa and grass fields that were flooded, Undersander warned. That's because of the likely increase in ash and the possible presence of several bacterial contaminants.

If source of the flood sources included livestock manure or overflowed municipal sewage, be aware of the possibility of disease-bearing pathogens, Undersander advised. Even if an adequate rainfall intervened before the harvest, consider fermenting that forage and feeding it to cattle other than milking cows or calves, he suggested.

Dashing the ash

Another consequence of a flood is the likelihood of a major increase of ash (sand, silica, soil) in the forage, Undersander pointed out. Even under good circumstances, it's inevitable to have 2 to 3 percent ash in harvested forages and the normal amount is 8 to 12 percent, he observed.

To limit the ash content in normal conditions, set the cutterbar at 2.5 to 3 inches for alfalfa and at 4 inches for grasses and consider using a flat cutting knife, Undersander advised. He acknowledged that the higher cut would reduce per acre yields by about 0.5 ton per year but cited benefits such as less ash and more regrowth and survival of grasses.

With the exception of wheel rakes which must touch the ground in order to turn, keep the rake tines off the ground and be aware that mergers are a better choice than rakes to reduce the accumulation of ash in forages, Undersander observed. Based on reports from equipment dealers about the frequency of bent and broken teeth on rakes, he surmises that far too many of them are striking the ground.

No horsing around

Ash percentages of up to 20 in the wake of a flood not only greatly reduce the feed quality for dairy cattle but they can easily be deadly to horses, Undersander warned. Because they are not ruminants, the sand or silica will not be processed in the digestive system of horses and could result in a blocked intestine, leading to a rupture and certain death.

Growers of forages should be doubly aware of those sensitivities of horses because of the good market for hay being fed to horses in Wisconsin, Undersander said. There are about 100,000 horses on farms in the state, but thanks to the popularity of horses raised in hobby settings, he estimated the state's population of horses is close to 900,000 — ranking second only to dairy cows in the large domestic animal category.

That explains the price premium enjoyed by the makers of small rectangular forage bales compared to the prices for large square and round bales, Undersander stated. Recent price for high quality hay have been running at about $230 per ton for the small bales to between $170 and $125 for large square bales, he noted. Because of transportation challenges, he said large round bales are discounted by $30 to $40 per ton from the large square bale prices.

2016 yield and quality

At the Extension Service's research plots, alfalfa yields at Arlington and Lancaster were up by 20 and 15 percent respectively compared to the 10-year average while there was minimal difference at Marshfield, Undersander reported. Somewhat surprisingly, perhaps due to some periods of high temperatures, the cool season grass yields were down a bit.

Reports from Rock River Labs on forage and corn silage samples from around the country show a bit of a fiber decrease from 2015 but the digestible fiber is much lower for the late harvested corn silage, Undersander indicated. For the haylage and dry hay in the Midwest, there is little year to year change in the total digestive tract digestibility scores.

Across the state, most farmers enjoyed high yields of alfalfa, leading to calls to Undersander by early in August with questions on the consequences of not taking another cutting for the remainder to the season. His answer was that research has shown no more than 600 pounds of plant debris per acre in the first cutting the next year. Based on that, there is no need for flail removal of the standing stems, he added.

Not taking a late cutting should also help with winter survival, Undersander said. To a question about this winter's weather which has left much alfalfa land either exposed or partially covered with ice or hard snow, he said the main concern with winterkill would occur if the temperature dropped to below 5 degrees at 4 inches below the soil surface.