1. Start with a soil test! If you haven't tested the soil in the last 3 years, you need to do that as soon as possible. Here is a link to our blog post about collecting and submitting soil samples. http://nchorse.blogspot.com/2013/03/soil-sampling-basics.html
2. Apply any needed lime based on soil test results. Most soils in NC gradually become more acidic with time. Addition of the proper amount of lime corrects soil pH and adds Calcium and Magnesium to the soil. A lime recommendation on a soil test report is like a prescription; it is based on not only the pH of the soil, but also on the density and buffering capacity of that specific soil. Over-applying lime can raise the pH too high, resulting in nutrient deficiencies and stand loss, so don't follow a rule of thumb for lime.
3. Know the type of grass you're fertilizing. Grasses are categorized as Perennials or Annuals, and as Warm-Season or Cool-Season. I'm focusing on Warm-Season grasses in this post, so I'll list the more common ones used in NC below.
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Warm Season Perennials
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Warm Season Annuals
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Bermudagrass
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Pearl Millet
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Bahiagrass
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Crabgrass
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Dallisgrass
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Teff (hay, not recommended for pasture)
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Switchgrass
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Sorghum or Sorghum/Sudan hybrids (NOT recommended for
horses due to cystitis)
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Gamagrass
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4. Know the levels of Phosphorous (P) and Potassium (K) needed. Phosphorous is very stable and accumulates readily in soil, while Potassium is moderately stable. Your soil test results will provide an Index for these and other minerals in soil; if they are high enough, the plants won't respond to additional application of these nutrients, and doing so would be wasteful. If P is needed, it can be applied in a blend with other nutrients (possibly with Nitrogen applications, as discussed in #5 below) or all the necessary P can be applied early in the growing season. K applications can be applied the same way, but K applications should be split on deep, sandy soils where K is more readily leachable.
5. Plan Nitrogen applications. Nitrogen (N) is very unstable in soil, so it is needed each growing season for grasses, and N recommendations are based on research trials, rather than soil test results. N can be applied in a blend with other nutrients, or alone via liquid or granular fertilizer. Nitrogen applications must be split throughout the growing season to avoid over-application. For warm-season perennials, apply 40 pounds/acre of N at greenup, then twice more in 6-8 week intervals. For warm season annuals, apply no more than 25 pounds of N at planting, then 40-45 pounds of N after every grazing period except the last. One word of caution; do not over-apply N or apply it during a drought because this can cause plants to accumulate toxic levels of nitrate. Certain plants, such as Pearl Millet, are nitrate accumulators and can accumulate dangerous levels during a drought even if N is not over-applied.
6. Select the right fertilizer. Fertilizer grades are listed as three sequential numbers, such as 20-0-20 or 19-19-19. These numbers always correspond to the percentage of Nitrogen, Phosphorous and Potassium in the blend, always in that order. So, 20-0-20 is 20% each of N and K, and has no P. 19-19-19 has 19% of all three. Remember, these are percentages, not pounds, so a fifty-pound bag of 19-19-19 has 9.5 pounds of each nutrient. For liquid fertilizers, you must know not only the percentage of nutrient in the fertilizer, but also the weight per gallon, since these are applied in gallons per acre.
After applying fertilizer, it is recommended to exclude animals from the area until enough moisture has fallen to wash granules into the soil or to wash liquid fertilizer from the grass leaves.
For more information about any of these steps contact your local Cooperative Extension Office. Follow this link to find your county center. https://www.ces.ncsu.edu/local-county-center/
Dan Wells
Extension Agent-Livestock
Johnston County Center
NC Cooperative Extension
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