It might be time to switch up your fertilizer application strategy
Logistics, timing, costs and machinery availability are all factors that can determine when farmers apply fertilizer to their fields. If you’re one of the many farmers applying fertilizer in the fall, it might be time to consider switching to spring applications when the crop actually needs those nutrients.
If it has been a while since you’ve visited your application strategy, take these five considerations for spring-applied nutrients into account.
1. Evaluate soil-test results.
Any nutrient-management plan needs to be based on solid soil-test results. Daniel Kaiser, extension nutrient-management specialist at the University of Minnesota, says that with land rents and other input costs increasing in many areas, farmers have tended to cut back on some important nutrients.
Not knowing what the soil holds could cost farmers productivity and profitability.
“In low-testing soils, it may be profitable to invest in nutrients like phosphorous,” Kaiser says. “You don’t want to miss out on yields by cutting back.”
2. Reduced chance for loss with spring-applied nutrients.
When fertilizer is applied during fall, the thought is that the nutrients will remain in place throughout the winter, says Shalamar Armstrong, Ph.D., a cover crops and nutrient management researcher at Purdue University.
If the winter is unseasonably mild or wet, for example, there is a greater possibility of losing fall applied nitrogen, even with an inhibitor in place.
“You want to think about how much you will lose and how much that will impact your crop uptake efficiency,” says Armstrong. “We promote the spring-applied nutrients, rather than the fall, because we think it can possibly increase plant uptake efficiency and reduce the amount lost via tile drainage to surface waters.”
3. Account for phosphorous needs.
Kaiser says in many cases, phosphorous is the most limiting nutrient for soybeans. Depending upon soil type and individual field conditions, a potassium deficiency can also negatively impact yields.
Farmers in a two-year corn/soybean rotation often apply fertilizer for both crops ahead of corn planting, allowing soybeans to mine remaining nutrients the following year.
“Farmers need to account for soybean fertilizer use,” says Kaiser. “If they don’t pay attention to that, they could be missing out on profitability.
Kaiser says he’s not seen much soybean yield response to nitrogen fertilizer, but it can be helpful in fields where soybean nodulation is deficient, such as in fields where soybeans have not been planted in the past.
4. Sustainability is always a factor.
As with many farming practices, sustainability comes into play when determining how to apply nutrients.
Armstrong notes that fall-applied nutrients most likely lead to more subsurface loss through tile drainage. Fall application also increases the risk of surface runoff and the loss of vital nutrients from your soil.
5. Timing and cost can impact decisions.
As with all inputs, expenses are an important consideration when determining when to apply nutrients. And fertilizer costs can vary from spring to fall.
“What’s the cost of fall versus spring applications and is there enough time to get it in,” are the questions Kaiser wants farmers to ask themselves.
Fall harvest and spring planting can be hectic times when farmers have compressed windows in which to complete their tasks.
If growers have a larger window of opportunity in the spring than the fall, and if the conditions make economic sense for their operations, spring nutrient applications may be a better fit.