Nitrogen Management After a Wet Spring
Robert Mullen, Ph.D.
Director of Agronomy
To say Dr. Robert Mullen is passionate about agriculture would be an understatement. He holds a Bachelor of Science degree in ag business from Cameron University, along with a Master of Science degree in plant and soil science and a Ph.D. in soil science from Oklahoma State University. In addition, Dr. Mullen has been published in a variety of scientific and trade journals. But it’s not just his academic accomplishments that make him unique. It’s his unwavering ability to take complex data and — in simple terms — explain how it impacts a farmer’s bottom line. Dr. Mullen delivers the kind of insightful observations that can lead to a more profitable business. As a leading agronomy expert, Dr. Mullen has a goal to further educate farmers on best management practices that improve their yields and maximize their return on investment.
This past spring has been one of the wettest on record for many of the Midwestern states. Unfortunately, wet weather drives nitrogen loss (of nitrate specifically). For coarser-textured soils, leaching of nitrate is the primary loss mechanism. For finer-textured soils, denitrification is a significant loss mechanism.
So, what do you do to decide if you should consider additional supplemental nitrogen this summer? For the western part of the Corn Belt (we will just call it west of Interstate 35), the pre-sidedress nitrate test (or late spring soil nitrate test) could be a viable option (different states have different critical levels — like Nebraska and Minnesota). For the eastern Corn Belt, pre-sidedress nitrate test is primarily limited to acres that have received recent manure applications or have a history of forage legume production (like Illinois and Indiana).
There have been ample opportunities for nitrogen loss this spring, and there is plenty of field evidence that young corn is already experiencing nitrogen stress (yellowing of the lower leaves in response to nitrogen deficiency). The reality is additional nitrogen is likely necessary to ensure a good yield, but there are some soil sampling options to determine if more is actually needed.