Fertilizer Planning for 2022 (07/15/21)
With the 2021 fertilization season in the past for most of this year’s crops, it is not too early to consider planning for the 2022 season. For most of the state, yields will be less than what was hoped for and in some fields, there will be no grain yield; all due to the drought. For every ‘bad’ there is usually a ‘good’. In this case, the good is that the residual nitrate should be very high after a disappointing harvest. In order to take advantage of the nitrate bonanza, it is necessary to soil sample and determine how much might be applied to the next crop. Also, it is important to soil sample for residual nitrate even if the field might be in soybean next year in the eastern half of the state where iron deficiency chlorosis (IDC) is a problem. High soil nitrate (roughly over 80 pounds of N per acre) makes IDC worse by interfering with iron (Fe) metabolism in the leaves. If high nitrate is found to be significant in front of a soybean seeding, then selection of more IDC tolerant varieties is especially important and consideration of seeding a companion barley/oat with or near soybean seeding will also help reduce the nitrate effect.
For those farmers who have yield monitors (and that is the majority of ND farmers) and even those who do not, it will be easy to see that yield will vary across fields. Residual nitrate likewise varies across fields. Sampling in a zone strategy instead of a composite soil test will greatly improve understanding nitrate variation across each field. Also, in the zone strategy, make sure that the salty areas are a separate zone. I think most will see that fertilization of these salty areas is usually not necessary the next year. For the rest of the field, given fertilizer rates used in 2021 and the yields that will come off of those fields, areas of fields with residual nitrate greater than 100 pounds of N per acre will not be uncommon. Taking advantage of the residual nitrate credit may make a difference in 2022 input costs of $50 per acre or more, which I think is a little more than the cost of having a field sampled.
Make plans now for sampling to happen this fall. Sampling in August is not too soon to sample after early season crop harvest.
Extension Soil Specialist