by Chris Hicks, County Director – UT Extension Smith County
May is here and that means hay harvest season is upon us. The modern disc mowers we use to cut hay have numerous advantages, most notably in speed and efficiency compared to sickle bar mowers that many grew up using. However, there is at least one drawback I have noticed that needs to be addressed.
Disc mowers that are not properly adjusted can “scalp” grass by cutting it shorter than the minimum 3-inch height that is generally recommended. While cutting this low might temporarily increase hay yield, in the long term it will significantly decrease the longevity of the stand of grass.
Cool-season grasses like tall fescue and orchardgrass store their energy above the ground in the stem base or tillers. Frequent mowing at a close height will continue to deplete these energy reserves, resulting in stand longevity issues.
We often tell homeowners that one way to improve their lawn quality is to increase mowing height, as it will give a healthier turf that is less prone to disease and competition from weeds. The grass in a hay field is no different and these modern disc mowers can cut closer than I would ever cut my lawn. Year after year of cutting at 1 to 2-inch heights will lead to hayfields made up of buckhorn plantain and foxtail, rather than fescue and orchardgrass.
Another consequence of mowing too close to the ground is increased ash content in hay. Ash content is a measure of foreign particles, like soil, in the hay. It decreases the palatability and quality of the hay, and can even lead to botulism when producing haylage.
So how high do we need to cut cool-season grasses? No lower than 3 inches and 4 inches would be even better. If you cut at this height, you’ll be amazed by how quickly your grass rebounds since it actually has some leaf area for the magic of photosynthesis to work. Furthermore, any temporary yield decrease is due to more of the low-quality stem being left in the field, and will be made up in the long run by increased stand life and productivity.
Making sure your mower is properly adjusted is an important part of preparing for a successful hay season. Depending on the make and model of machine, several methods can be employed to obtain higher cutting heights including stroke-limiting collars, high-clearance skid shoes, and adjusting the cutterbar angle.
Cutting height matters when harvesting hay, and can be the difference in a stand that is healthy for years vs. one that is unproductive and overtaken by weeds.
The University of Tennessee Extension, Smith County offers its programs to all eligible persons regardless of race, color, national origin, sex, age, religion, disability or veteran status and is an equal opportunity employer.
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