What is in this article?:
- With fertilizer prices at a near record high, the admonition to base fertilization on soil tests should not have trouble being heard.
- Soil testing remains one of the cheapest practices a forage producer can use.
- For the past few years, fertilizer prices have increased significantly and have not come down much — producers must learn to manage costs and maintain optimum production.
- Fertility recommendations should be based on how much nitrogen, phosphorus and potassium, as well as secondary and micronutrients are available in the soil.
N, P and K
“Nitrogen, phosphorus and potassium are needed in the largest quantities.”
Corriher said producers should set production goals and fertilize to meet those standards. For a 1 ton per acre forage production goal, coastal bermudagrass needs 50 pounds of nitrogen, 14 pounds of phosphorus and 42 pounds of potassium. For 2 tons, rates increase to 100, 28 and 84.
One ton production would need 8 pounds of calcium, 3 pounds of magnesium and 4 pounds of sulfur. The rate increases to 15, 6 and 8 for a 2 ton yield goal.
Nitrogen may be the most essential nutrient. “Without nitrogen we get no growth. If nitrogen is deficient, grass will have a yellowish color,” she said. Ample nitrogen improves the grass’ ability to compete with weeds “and possibly decrease herbicide needs. Also, nitrogen increases forage production and crude protein.”
Nitrogen is mobile, leaches and volatizes.
Phosphorus, Corriher said, stimulates early growth and root formation, improves moisture and nutrient uptake and promotes optimum forage yield and quality. Phosphorus is immobile and will not leach or volatize. “It is subject to stratification and may build up in the top 2 to 3 inches of soil where it us not readily available to the roots.”
Potassium aids water use efficiency, increases disease resistance and improves cold hardiness. It also does not leach is not volatile.
“Potassium deficiency is uncommon in heavy soils and is more likely to occur in medium/coarse textured soils. Deficiencies may result in stand decline and winter kill.”