Phosphate fertilizers are slow to incorporate; therefore fall-applied phosphate is preferred. Small amounts (25% to 30%) of spring applications may become available, the majority will be usable the following year.
Top Dressing Phosphorus On Mixed Grass Forage in Fall Is Superior to Spring
Rate Fall Spring
lbs/Acre Tons/Acre (12% moisture)
0 1.8 1.8
40 4.4 2.4
80 4.1 2.9
120 5.0 2.9
*Source: Ludwick and Rumburg, 1976.
**Phosphorus fertilization can increase protein in hay and stimulate legume growth. Fertilization could increase yield and quality.
**Acceptable soil phosphate level to support legumes is 12-14 parts per million and grass is 9-10 ppm. Levels below this will inhibit production. Usually 30-40 pounds of phosphate applied annually is adequate for 3 to 4 tons of production.
**An interest savings could be gained by delaying spring phosphate applications until fall. An additional price discount is often available on fall fertilizers, but there would be an application cost.