Set Disc Mowers High to Prolong Grass Hay Stands

Photo from deere.com

Over the past year I have had producers come into the office with complaints about orchardgrass stands.  The majority of the time I felt like it was due to soil fertility.  While reading the June edition of UK’s Forage News, I read that while soil fertility does play a large role in stands, UK Extension Forage Specialists are now making a new recommendation for producers concerning mowing heights.

Dr. Garry Lacefield and others conducted a survey of forage specialists across the U.S. a few years ago on the reasons orchardgrass hay fields seem to be thinning out in recent years. Survey respondents identified lower fertility, severe weather conditions, insects, and diseases as factors contributing to stand loss, but they felt that the number one reason for shorter stand life was low cutting heights. And low cutting heights were mainly attributable to disc mowers.

Disc mowers are great hay cutting tools, with their ease of operation, speed of harvest, and ability to easily harvest thick stands. These mowers allow producers to easily harvest at 1 to 2 inches. Low cutting heights like this are fine for alfalfa since it regrows from energy stored below ground in its large taproot, but can be disastrous for grasses like orchardgrass. Orchardgrass has a more upright growth habit and low cutting removes all the leaves needed for photosynthesis and the base of tillers (stems) where carbohydrates are stored for regrowth.

An Asbury University student, Leah Saylor, conducted a research experiment on orchardgrass cutting height at UK 4 years ago. Leah found that just one season with low cutting heights significantly reduced stand longevity and increased weed infestation, regardless of the addition of fertilizer treatments. The results show that the recommended cutting height of 3 to 4 inches for orchardgrass and similar grasses is essential to maintain thick, weed free stands. Most disc mower manufacturers sell skid shoes to insure higher cutting heights. These are well worth the price, especially if they help in producing a better stand of grass hay.

For more information about forage production, contact the McLean County Cooperative Extension Office at (270)273-3690.  Educational programs of the Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability or national origin.


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