This is a good time to top-dress alfalfa fields with phosphorus and potassium fertilizers
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Many growers have cut alfalfa this past week. This is a good time to top-dress alfalfa fields with phosphorus and potassium fertilizers.
We recommend fertilizer applications after the first cutting. Generally, the first cutting is rank because of spring rains and good growing conditions. Therefore, we like to apply nutrients after the first cutting so they can be used during the next cuttings throughout the rest of the season.
The crop removal rate of one ton of alfalfa is approximately 12 pounds of phosphate and 50 pounds of potash. Alfalfa is a heavy feeder of potassium fertilizers.
A local field had an area that was stunted and growing poorly. The height difference was 15-inches between the stunted area and the rest of the field. We send a sample and found that area of the field was very low in phosphorus. The grower was going to make a one-time specific application to that area of the field. The stand will stay longer with the proper fertility.
When using soil test recommendations, the recommendations generally indicate multiple years of application rates, not just a one year build-up program. Read soil test carefully to determine the buildup time line. The University of Missouri is an eight-year build and maintenance program.
A good soil testing program is important. The interpretation is just as critical as taking the soil sample. If you have questions about the interpretation, take time to ask.
For more information, contact Wayne Flanary, Regional Agronomist, University of Missouri Extension at 660-446-3724.