In-Season Fertilizer Application

Contributed by Mitiku Mamo, UNL Extension Educator, Crops and Water

As you have all noticed, spring precipitation to date has been a lot less than the average for our area. For example, at Haskell Ag Lab in Concord, NE we received less than half an inch for the entire month of April compared to the monthly average of 3.3 inches. While this below average spring precipitation have provided ideal weather conditions for pre-plant fertilizer application and planting, dry soil after application of urea or UAN means that the fertilizer sits on top of the soil and is subject to nitrogen loss due to volatilization.

 This is especially of concern for no-till fields where incorporating the fertilizer is not an option and non-irrigated fields that did not receive a rainfall of at least half an inch within a few days of fertilizer application that would have helped move the fertilizer into the soil.

 Of course, the growing season is only starting and nitrogen can be lost through other means such as water runoff, leaching into the ground water and denitrification.

 If you think you may have lost some nitrogen, there are many ways to determine if nitrogen has been lost and make in-season adjustments. According to the April 29 CropWatch article titled “Tips for In-season Nitrogen Management in Corn”, the Late Spring Soil Nitrate Test works well for fields with medium and fine textured soils but may not work for sandy soil. Use of crop sensors is also possible, check out the CropWatch web site or call your local extension educator for how to use a Chlorophyll meter or a crop sensor such as the Rapid Scan.

 Because under fertilization of nitrogen can cause significant yield losses, it is worth your time to determine if you might have had some loss and prepare a plan to adjust accordingly.

 If you have further questions you can reach Mitiku Mamo at