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Knowing when to harvest forage is the key

April 22, 2008|By JEFF SEMLER

Spring has sprung and with the arrival of warmer temperatures last week the cereal rye crop has rapidly begun to grow and develop.

Stan Fultz, dairy extension agent from Frederick County, and I were working in our forage plots last week and we noticed how fast our rye cover crop was taking off.

I know in some areas this crop is quickly approaching knee height. This indicates that the harvest for highest quality forages is just around the corner. Are you ready?

Many dairy producers have adopted management practices to maximize forage quality and yields from ryelage. These individuals quickly plant rye into harvested silage acreage in the late summer and then gain the advantage of a winter cover crop, a way to recycle fall applied manure nutrients and provide quality forage at a time when other forage crop supplies are getting short. Others have learned to despise this crop based on experiences when feeding an over-mature or too wet ryelage crop.

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To ensure high quality ryelage harvest, producers must have harvest equipment ready to go. The quality of ryelage rapidly decreases with maturity and one day in harvest delay can make the difference between high-quality and average, to poor-quality forage. If producers rely on custom harvesters, these individuals should be contacted now to plan approximate harvest schedules.

The most successful ryelage managers time harvest for maximum plant sugar levels with the highest level of digestible forage fiber. These individuals time mowing of rye stands just prior to head emergence. Their goal is to have no more than 5 percent of the tillers showing any sign of emerged heads. You can monitor where the head is within the plant stalk by feeling for it or by carefully dissecting the tiller. Once the flag leaf has emerged, the seed head is soon to follow.

Cereal rye can provide high levels of dry matter per acre. This large amount of forage can greatly affect rapid dry-down following mowing. Ensuring a rapid dry down maximizes the level of plant sugars in the plant resulting in better fermentation in the silo and higher quality forage for the cow. Mowing and putting the forage in as wide a swath as possible will aid dry-down. By not conditioning the plant, the forage will continue to respire in the field post mowing and more rapid dry down will naturally occur. Conditioning breaks the "plumbing" of the plant and limits dry-down rates.

Many successful ryelage producers also ted their rye to speed dry- down. Most will ted as soon after mowing as the surface of the swath is dry. This is usually followed by a second tedding when the tops of the forage is dry and finally a rake is used when moistures are close to harvest targets (62 to 65 percent) to prepare the field for chopping.

Spring also brings on alfalfa growth and many folks are looking at alfalfa stands questioning if they are worth keeping another year or should they be harvested early and rotated to corn this spring. Marvin Hall, Penn State Forage specialist says, "Unfortunately this is not always a yes or no decision."

For established stands, the magic number of plants that traditionally indicated when it is time to rotate out of an established alfalfa stand is four to five plants per square foot. However, depending on fertility and weed invasion, alfalfa stands with four to five plants per square foot can yield as much as a stand with many more plants per square foot. The correlation between plants per square foot and yield is very low since individual alfalfa plants respond to decreasing stand density by producing more stems. Increased number of stems per plant compensates for fewer plants and maintains the yield.

"A better indicator of the productivity than the number of plants is the number of stems per square foot," Hall says. "Fields with 55 or more stems per square foot produce maximum yields. As the stem number declines below 55 per square foot, yields begin to decline. Once the stem number falls below 40 per square foot, alfalfa fields begin to lose profitability and should be rotated out of alfalfa."

Alfalfa plantings made last fall or this spring plant density in new alfalfa seedings should be a minimum of 15 plants per square foot. This greater density is needed because the plants have not developed large crowns yet and will consequently have fewer stems per (directly related to yield) plant than older plants.

So as the temperature rises so does the work rate and need for quick decisions.

Happy Earth Day to all of the Earth's stewards.




Special thanks to Marvin Hall and Paul Craig, colleagues from Penn State, for providing some of the information included in this article.

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