Dan Undersander’s thoughts on forages

Extension agronomist offers his tips on growing high-quality forages

A well-known promoter of high-quality forages, Dan Undersander is retiring this summer.

Dan Undersander, a forage extension agronomist from the University of Wisconsin, is one of North America’s best known promoters of high-quality forages. I have known and worked with Undersander for many years and sometimes we would be on the same program. As he will be retiring this summer, I wanted to record some of his thoughts on growing high-quality forages.

“It all starts with making the decision that you want to grow some forages” says Undersander. “You need to set some goals when planting forages. If you are planning on producing hay, or baleage or silage you need to aim for a 60 per cent legume stand with about 40 per cent grass growing in the mixture. If it is for pasture you need to aim for 40-50 per cent legumes and the remainder in grass. In both cases you are looking for high yield and quality and, in the pasture, you need good seasonal distribution of forage yield.”

“There are big nutrient benefits to growing pure alfalfa stands in rotation with field crops. I have seen increases in corn and wheat yields and increased protein levels in wheat following corn. This is due to the extra nitrogen left in the soil following an alfalfa crop and a rotational benefit of unknown cause.”

“As always, choose your forage varieties with your end goal in mind. Seed in a really firm seed bed so that the soil is packed around each seed and reduce the competition from weeds.”

When it comes time to harvest your forages, Undersander had some more suggestions.

“The quality of the harvested forage that reaches the cow’s mouth depends on three things: stage of maturity at harvest; how long it takes from the start to finish at harvesting time, and the quality lost in harvesting and through storage.”

“The cutting height for alfalfa stands should be between two and four inches to maximize yield while grass or grass-legume stands should be cut between three and four inches. Grasses need this higher cutting height because of the energy stored in the stems bases for regrowth potential. These cutting heights will be high enough to keep a wide swath off the ground so that air can flow underneath the swath and assist in drying the crop.”

“After the forages have been cut, the moisture in the plant moves along the stem. At first, most of the moisture loss is through the plant’s stomata if the forage is put into a wide swath covering 70 per cent or more of the cut area. The stomata stay open for a short time following cutting but the more sunlight they get the longer they stay open to release moisture. Shading by clouds or by forages in the swath will close the stomata and prevent moisture loss.”

“Mechanical conditioning at the time of cutting can just about double the rate of drying. The goal is to have a minimum number of legume leaves damaged and have the legume stems scraped or broken about every two to four inches. We find that roller conditioners are best for using in alfalfa and alfalfa grass stands and the flail or impeller conditioners work well for grasses. The big thing is to adjust the conditioner to minimize legume leaf loss.

“With these wide (70 per cent) swaths you are basically reducing the swath density, increasing the overall exposure to the sun, increasing the crop surface temperature and keeping the crop off of the ground compared to the denser narrower windrows. The improved quality occurs because there is less respiration loss of starch and sugars due to the faster drying time.

“However, the wider swath must be raked to a windrow width to match the width of the pickup on the forage harvester or baler, which adds an extra operation. This would be offset by the increased forage quality. The other thing to remember when using a pull-type mower conditioner is to have only one side of the tractor run over the swath to reduce wheel damage on the stubble. The swath will need to be raked or merged to the width that matches the forage harvester or bailer but when making haylage one should rake just ahead of the forage harvester.

“To reduce leaf loss, alfalfa should be raked when the moisture is above 40 per cent and grass above 25 per cent moisture. If you are unable to rake at these moisture levels then you can rake with dew on the forage to minimize leaf loss. Raking boosts the drying time but only on the day of raking. After that, drying slows and is really determined on the amount of sunshine and humidity.

“We have found that wheel traffic on forage stands can greatly reduce future yield. Thus you need to minimize driving on the field and to use the smallest tractor and the largest harvesting equipment possible. Don’t use dual wheels on the tractor. Do the driving on the field as soon after harvest as possible and use the most direct route to get off the field. We find that wheel traffic damages the plant’s potential to regrow and the longer after cutting the more damage results from the wheel traffic.”

“There has been a lot of talk about cutting forages in the afternoon. The plant produces its maximum amount of starch and sugar late in the afternoon. After cutting, respiration still occurs for a short period and the plant continues with tissue growth by metabolizing sugars and starches. Rapid initial drying will reduce loss of sugars and starches and produce higher-quality forages. There has been some research showing that cutting later in the day can result in higher levels of these sugars but the increased respiratory losses overnight and longer total drying time may delete the benefit of afternoon cutting. While afternoon cutting can benefit sugar levels in areas, such as the Great Plains of the United States, where rapid drying occurs, Midwestern data has not shown any forage quality advantage to afternoon cutting,” said Undersander.

I asked Undersander what he thought about the new Round-up Ready/reduced lignin alfalfa varieties that have been introduced into the United States. These varieties have better digestibility than traditional alfalfa and allow producers to harvest more high-quality alfalfa by lengthening the window of the harvest season.

He said, “I helped Forage Genetics International get the release of the RR alfalfa because I wanted the breeding technique available for alfalfa to produce the low lignin alfalfa and other GM traits. I did not think Wisconsin farmers would ever benefit from the RR trait but now believe my first thoughts were wrong. RR alfalfa is beneficial to farmers whenever we have a cool spring — alfalfa does not grow much below 13 C but weeds do and they can get too tall for post-emergence weed control before the alfalfa is big enough to apply the herbicide.  Additionally, on late spring plantings, Roundup controls warm-weather weeds such as crabgrass, dandelions, knotweed, etc., better than other post-emergent herbicides.  Roundup is also better for fall-planted alfalfa because the alternative, Poast+, only controls grasses like volunteer small grains but Roundup will also control broadleaf weeds that appear.”

Of course, the Roundup trait is of little benefit if planting grass with the alfalfa.  Though options exist for planting alfalfa, using Roundup to control weeds, and then seeding the grass, either later in the spring or in the fall is a possibility.

There is no current plan to grow alfalfa varieties with the reduced lignin trait but not the Roundup trait. The cost and difficulty of production would be too great.

“A new genetically modified trait will be elevated bypass protein. The breeding process has been under way for about eight years and they are close to getting material ready for the market. I think this will happen in about five years. We are also seeing the need for resistance to new races of some old diseases,” he said.

“As I look to the future of the forage industry there will be many changes in hay harvesting equipment. Many new mowers have autosteer that works with the tractor. Based on our wheel traffic work, some companies are developing bale accumulators to reduce driving on the alfalfa. The pre-cutters on balers have been shown to reduce feeding losses and increase animal intake and performance. A company I am working with is marketing variable hay preservative application equipment where instruments measure hay moisture going into the baler and adjust the preservative flow rate to match the need. We are also seeing greatly expanded use of baleage for beef cattle producers to harvest higher-quality forage of cattle over winter.

“Milk production in dairy cattle has doubled in the last 30 years due largely to higher-quality forage being fed, and stockers cattle have the potential for twice the average daily gain, though not obtained yet but, again, higher-quality forage is needed. We cannot produce hay or haylage like 30 years ago and expect to meet increasing animal needs” concludes Undersander.

About the author


Duane McCartney is a retired forage-beef systems research scientist at Lacombe, Alta.



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