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For several years, we have been urging our grazing clients to let their grass pastures get a little taller before turning in and not graze them shorter than four to six inches. This has a number of benefits to the grass plant that make it more productive. With most plants, root mass mirrors vegetative growth; therefore, taller plants have deeper roots which access more moisture and nutrients. Maintaining a leaf canopy preserves soil moisture and keeps the soil surface cooler. These factors are critical to the productivity of cool season grasses in the summer. It is equally important to remember that grass plants store energy reserves in the lower, leafless part of the stem. As grass plants increase in height, this area also extends, storing greater reserves. Completely defoliating a grass plant (either by overgrazing or mowing too low) reduces its energy reserves, destroys its photosynthesis factory, and causes many deeper roots to die off. This stress together with adverse weather or inadequate fertility result in slow recovery, prolonged dormancy, and possible stand loss. To maximize the yield and longevity of a grass pasture, it is critical to adopt a taller grass management strategy.
Grazing height also influences clover growth. Having a highly productive white clover, like Alice, in a pasture fixes a significant amount of nitrogen for the grass; however, overgrazing a mixed pasture in the summer often leads to an extreme proliferation of the clover, which under certain circumstances can cause bloat. Generally, dairy cattle fed on pasture are considered to have considerably fewer health issues than confined cows, yet the high protein levels in less mature grass can cause health problems related to elevated Blood urea Nitrogen (BUN) and Milk Urea Nitrogen (MUN). While many producers and nutritionists choose to balance the diet of cows on high protein pasture with grain, dry hay, or silage, there is another method – tall grass grazing.
Improved cool season forage grasses that are 10-18 inches tall, but have not headed, have a more ideal protein level (16-20%) together with two to four times the tonnage compared with the same stand grazed at six to ten inches tall. Palatability, digestibility, and energy content can be maintained at high levels with adequate nutrition. To balance a feed ration for animals on high quality pasture without adding grain, hay, or silage, it is necessary to allow the pasture to mature, but not head. So if tall grass grazing is better for the grass and better for the cow, why isn’t everybody doing it? Profitable tall grass grazing requires three things:
- Late-maturing, forage genetics that are capable of remaining vegetative for up to 35 days;
- Healthy, biologically active soils with balanced fertility that will support “tall” vegetative growth;
- Foliar fertilization to maintain optimal growth rate, nutritional quality, and slow down the senescence or hardening-off of mature plants.
In addition, management techniques such as “Mob” grazing (ultra high stocking rate and moving the break wire often) are essential to maximize consumption and minimize trampling loss in a tall grass pasture.
While beginning to adopt these principles will likely benefit every grass farmer, not every farm is ready to support it. We recommend working with your local FSM dealer to develop a systematic plan for building your soil, improving your grass genetics, and fertilizing your forages to maximize high quality production.
Drawn from the combined experiences of Kevin Fowler (Fowler Seed Marketing), Gary Campbell (Agri-Energy Resources), and Reggie Destree (Dramm Fish)