Nitrogen Deficiency
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By Dairyland Seed Agronomy Team
By Dairyland Seed Agronomy Team
During the 2024 growing season, much of the Dairyland Seed footprint experienced wet conditions early on, followed by an abnormally dry period. In most (but not all) of the Dairyland Seed footprint in 2025, we started off dry and had a few rainy spells accompanied by cooler temperatures.
With the rainy spells in the growing season of 2025, we are seeing standing water or ponding in portions of fields. Whenever I see standing water in planted fields this time of year, I think of two things: nutrient deficiencies (specifically nitrogen followed by sulfur) and mosquitoes.
As soil temperatures increase, the soil's biological activity starts to increase, and soil mineralization begins to supply more nitrogen into the soil profile as ammonium. Ammonium is positively charged and held in the soil and organic matter which is negatively charged. (When you think about the negative and positive charges, remember how magnets work. Opposites attract and like-charged particles repel.)
Because ammonium is held in this bond, it is not subject to movement from excess water and is available to the plant for uptake. When soil warms up to 50 to 60°F or greater, soil bacteria (nitrosomonas) change the ammonium into nitrite. Another soil bacteria (nitrobacter) changes the nitrite into nitrate. Both nitrite and nitrate are negatively charged. These negatively charged particles repel the negatively changed soil particles. Because nitrite and nitrate are not held in a bond like ammonium, they are subject to leaching. In this instance, leaching is when water is pushing or pulling these nitrates and nitrites through the soil profile away from the plants’ root system. Leaching is a bigger concern on coarser or sandier soils. Also, the more water you have moving through the soil profile, the more leaching will take place.
When we have soils that are at or above water holding capacity and ponding, we have very little or no room in the soil profile for oxygen. This depletion of oxygen in the soil makes an anaerobic condition. When soils become anaerobic, they are more prone to denitrification. Denitrification is when nitrite and nitrate are converted into nitic oxide and released into the atmosphere.
Both conditions, leaching and denitrification can be lessened by utilizing nitrification inhibitors such as N-Serve® and Instinct® II. Other products will need to be utilized to work on the mosquitoes.
With the water we have received, it would be recommended to take nitrate samples to see what nitrogen is present and what we may need to apply.
If you have questions regarding this or other Agronomic topics, contact your Dairyland Seed Agronomist.