Information Management to Maximize Your Yields

Should fall fertilizer strategies change because of the drought?

This year’s drought and in some areas hail, have made for some stressful times in your farming operations. Despite that, it’s still a great time to be in agriculture with all of the advances and continued progress over recent years. We need to continue to be safe and to plan for next year. Some may be wondering if our fall fertilizer strategies should change because of the drought, see what Rick Vanden Huevel at VH Consulting, Inc., our soil lab, has to say:

With the drought of 2012 significantly impacting crop yields, some producers may be giving thought to little or no fertilizer application to next year’s crop. This varies though as yields are so variable across the state. Though this may make sense for a couple of situations, in most cases it does not.

SciMax Learning Group members’ fertilizer recommendations utilize actual yield data from their own fields by every 60 ft. by 60 ft. squares for crop removals, management zones that are established for Variable Rate planting recs or just mgmt. zones that are consistent year after year, and finally using the soil test data from 2.5 acre grids.

This is very unique in the industry and a huge benefit to those involved in the SciMax Learning Group. Making recommendations this way helps manage variability between yield and soil tests data. This year with all of the stresses there are major differences in crops where management of fertility has been a focus. These fields have not shown as bad of stress and yield will show that it pays.

Soybeans in 2012 are likely benefiting from a fertilizer application made in 2011, and corn of that year, which had good yields, removed a lot of nutrients. Cutting back in this situation doesn’t make sense. Corn in 2012, in rotation or continuous, still will produce a crop which can remove significant amounts of nutrients in many parts of IA or the Corn Belt for that matter.

Taking credit for a partial crop is not an exact science. Soil testing and the recommendations made from it are not sensitive enough, in most instances, except SciMax recommendations, to measure or compensate for the partial crop removal for a single year.

Keep in mind that while the crop field average may not be what you want, many spots of a drought stricken field will still yield well. Many parts of your field will have large crop removals rates. After a year like 2012, nutrient variability across fields is likely going to increase. Nevertheless, if no grain or stover is harvested, consideration for little or no fertilizer may be a valid option.

Also, if your soil tests are in the very high range for P and K, for the great majority of a field little or no fertilizer may be a valid option. If your last fertilizer application was very aggressive (full crop removal plus a build amount), trimming the next application rate may be an option. But most fields will not fit the above criteria.

For most growers, it is likely best to add nutrients as usual and consider it a build year (at least for parts of your fields) for the high yields many producers are trying to achieve with today’s technologies and greater yield potential.

Considerations for carryover N in continuous corn may be tempting, but moisture between late fall and spring may change carryover amounts. Characterizing that change is not easy. Furthermore, spring nitrate N tests are most often done on composite samples (very large areas), but as mentioned above, variability is going to be very significant from variable yields as well.

If there is an interest in crediting unused N, perhaps some zone sampling for spring nitrate N could be considered to provide a credit. Otherwise, stay with your original plan or the original plan minus a very modest credit for unused N (perhaps 10-15 lbs. N/A).

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