There’s not much exciting about soil fertility, but Oklahoma State University (OSU) researchers recently reminded that it is the foundation to forage production and nutritive value.
“Lack of attention can easily necessitate increased purchase of off-farm feed and forage, decreased animal performance and reduced level of profitability of a forage-livestock enterprise,” says Brian Arnall, OSU assistant professor of plant and soil sciences.
Arnall explains the first step in a soil-fertility program is to obtain a soil sample for analysis of its levels of nitrogen, phosphorus and potassium, as well as the pH. Under certain circumstances, analyses for other nutrients also may be required.
Based on the yield goal for specific forage crops, written recommendations for the level of each fertilizer nutrient required are usually furnished by the laboratory conducting the analysis.
After correcting the soil pH level to greater than 5.7 and meeting the phosphorus and potassium needs, there are only two basic fertilization principles required for introduced, warm-season grasses.
The first principle is that nitrogen fertility is required for grass growth; the second is that nitrogen fertilization should be based on a reasonable yield goal for the region of production, says Daren Redfearn, OSU associate professor of forages.
“The first nitrogen application should be in early May, just as the grass is beginning to grow and ahead of late-spring rainfall,” Redfearn says. “Properly timed fertilization can result in better utilization of late-spring rainfall.”
Here’s his warm-season grass fertilization checklist:
• Conduct a soil test
• Lime as recommended
• Apply phosphorus and potassium as recommended
• Identify a reasonable yield goal
• Apply nitrogen fertilizer ahead of moisture based on yield goals.