Harvesting Options for Summer Annuals

By: Mike Estadt, AgNR Educator, OSU Extension, Pickaway County (originally published in The Ohio Cattleman early fall issue)

Summer annuals such as sudangrass or sudangrass X sorghum hybrids are likely near ready for harvest.

This month I drove across I-70 interstate to Kansas City, Missouri. Along the way I observed at least a dozen semi-trailers headed east with loads of high-quality hay. Some of this hay may have been delivered to Ohio where very little good hay has made this year. I also saw several fields planted with summer annuals where corn should have been.

Beef producers in Ohio who have planted summer annuals such as sudangrass or sudangrass X sorghum hybrids and pearl millet as a substitute for high-quality cool season grass hay should prepare for the immediate harvest beginning this month.

Most smaller beef operations are not set up for feeding silage so there are two options available. Green chopping and hay/baleage.

Green chopping may be an option for producers especially if pastures are getting short of forage. Sorghum-sudangrasses are well suited to a green chop program. Field losses are less from green chopping than from grazing or haying.

Maintaining proper harvest height encourages tillering

However, the fast growth rate of sorghum-sudangrass results in variable amounts and quality of feed throughout the growing season. When grass is young and growing rapidly it may contain 20 percent crude protein and produce a highly succulent feed. As the crop grows taller and nears maturity, the protein content may drop to 7 percent or less, and fibrous, low quality green chop is produced.

Dry Hay and Baleage– Dry hay harvests are difficult with summer annuals. Ideally cut at a 30 to 36- inch height. Leave 6 to 8 inches stubble height for best regrowth and aeration of the cut forage swaths. A second harvest will also be increased if forages are harvested at this stage. (Table 1)

Table 1– Approximate mechanical harvest and stubble heights of selected summer annuals

Hay/baleage management
Species Height Maturity stage Stubble height*
(inches) (inches)
Pearl Millet 30-40 Early head 4-6
Sorghum-sudan 30-40 Early head 6-8
Sudangrass 30-40 Early head 6-8

* Stubble cut below these height ranges may result in poor or no regrowth.

Condition using more roller pressure than for conventional hays. If your mower has intermeshing rollers it is advised to adjust these rollers as tightly as recommended by the manufacturer.

Create as wide and fluffy a windrow as possible. Do not windrow until the top of the windrows are dry enough for baling. It can take an entire week of sunny weather to cure the forage for dry hay harvest. Tedding this forage will be difficult as most tedders are not designed to handle such a heavy crop.

Baleage – To hasten baling and preserve field losses associated with dry hay the best option for harvest and storage of summer annuals is to wrap bales either individually or inline.  Wrap bales as quickly as possible after baling to reduce internal heating and associated quality decline.

Cautions and Considerations of Harvesting Summer Annuals

Green Chop– Nitrates can become a problem in a green chop program under certain growing conditions such as drought and heavy nitrogen applications. Do not feed green chop that has heated in the wagon, feed bunk, or stack, or that has been held overnight. Nitrates are converted to nitrites as plants respire; nitrites are about 10 times more toxic than nitrates.  Feed only what can be consumed in a day.

Dry Hay and Baleage– Prussic acid poisoning a much less common occurrence when the affected summer annual is cut and baled as hay, since hydrogen cyanide (prussic acid) dissipates within a few days. However, toxic nitrate levels in hay will not go away, no matter how much time it is given. Thus, an analysis of any forage suspected of high nitrate levels is crucial in understanding how to deal with the affected forage. Nitrate levels would ideally be measured prior to harvest. If nitrate levels are found to be high, increase the cutter bar height to 2 to 4 inches above the target specified in the table so that the nitrates that are highly concentrated in the lower stalk are avoided.

If baleage is been made in late August/early September an application of approximately 50 units of nitrogen fertilizer should be made to hasten regrowth to increase yield for the subsequent second harvest.

To reduce hay waste at the hay ring from cows pulling out long strands of feed, utilize a net wrap baler with cutting knives to facilitate smaller forage particle size. These balers with knives improve bale density and hay fermentation.  Bales will tend to weigh several hundred pounds heavier even when only half the knives are engaged. These denser bales will use less net wrap, plastic to wrap the bales which can result in monetary savings and time savings.


Dr. Dennis Hancock, Extension Forage Specialist, University of Georgia

University of Wisconsin-Madison https://fyi.extension.wisc.edu/forage/sorghums-sudangrass-and-sorghum-sudan-hybrids/

The United Sorghum Checkoff https://www.sorghumcheckoff.com/news-and-media/newsroom/2018/07/10/late-planting-of-sorghum-for-hay-or-grazing/


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