UT Beef and Forage Center

Forage Management and Production- Article

Gary BatesDr. Gary Bates, Professor and Director, UT Beef and Forage Center    

(865) 974-7324

gbates@utk.edu

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There have been a lot of advances in the technology used on the farm.  One of the biggest area of changes has been in the equipment used for making hay.  Sickle mowers and square balers were the equipment used 50 years ago.  Now, disk mowers and round balers are standard on almost all beef operations.  This equipment has may hay cutting, baling, and transport a lot faster, and taken a job that required a large amount of hand labor and made it basically a one-man job. 

New technology isn’t always without its problems, however.  One of the issues that has developed with disk mowers is the tendency for producers to cut their fields very short.  It isn’t unusual to see a one or two-inch stubble height after a produce has cut hay with one of these mowers.  There have been numerous research studies showing the impact of the amount of stubble left after mowing on the persistence of cool-season grasses such as tall fescue and orchardgrass.  The recommendation from these studies is to leave at least three inches of stubble.  Cutting below that will reduce the persistence of the stand, shortening its productive life.

Many of the grasses we use for hay store some of their carbohydrates for energy in the lower two inches of the stem.  When we cut below this height, this stored energy reserve is removed, making it harder for the plant to regrow.  We have also removed all of the leaf area, so the plant can’t absorb much sunlight for photosynthesis.  This makes regrowth slow.  Repeated close mowings with significantly reduce the stand life of a field.  As the stand thins, there will be increased weed pressure and decreased yield.

I have been asked several times why tall fescue and orchardgrasss fields don’t last now as long as they did in the past.  Part of that could be simply due to our memories.  Things often seemed better in the past compared to current conditions.  But a lot of it is due to how close a field is cut during hay harvest.  Consistently cutting below three inches can cut several years off a stand, especially if close cutting in spring is followed by a summer drought.

One of the best things you can do is check the residual height left after you mow.  For grasses like tall fescue and orchadgrass, you need to leave three inches of stubble.  For taller grasses like sorghum x sudangrass and native grasses, you need to leave 6-8 inches of stubble.  It may be as simple as a simple adjustment on the angle of the blades.  To get to the taller height, you may need to purchase some sort of shoes or skids to raise the mowing height.

If you have noticed that your hayfield isn’t as thick as it once was, check your mower to see how much stubble is being left.  If it is below three inches, then raise the height.  You won’t be losing much in yield, but you will be gaining a lot with respect to your plants vigor and persistence.