One of the concerns producers have when harvesting silage is the amount of nutrients that are being taken from the land. According to a recent meeting regarding drought silage the following figures were presented.
For each ton of silage removed the following nutrients will be removed:
- Nitrogen – 9.4 lbs
- Potash – 3.6 lbs
- Potassium – 9 lbs
With the assumption that potash is $954 per ton, phosphate is $828 per ton, and nitrogen is $728 per ton, and the corn produces 6 ton of silage per acre, $54.72 of fertilizer will be removed from the field. In other words, at these prices $9.12 of fertilizer must be replaced for every ton of silage taken off of your field.
Many producers worry about the amount of nitrogen that is being taken off. To me this is not an issue because nitrogen does not attach to soil particles and is very leachable. Even if we did not take the material off as silage we would still lose most of our nitrogen under normal winter conditions.
The best way to save this carry-over nitrogen is to plant a cover crop and tie it up in the plant over the winter. This can be done with various crops, including winter rye. If you are interested in cover crops there is a lot of material available and a lot of good research being done on this topic. I believe that, in the near future, cover crops will be an integral part of most farms nutrient management plans.