June 1, 2022
Fertilizer cost and availability going into the 2022 season has been a challenge across most of the corn growing region. With potassium and phosphorus, we can rely on soil reserves to help get through the price increase and potential availability issues for a year or two. Nitrogen, with its potential to move through soils (leaching), cannot be counted on to be “banked” from one year to the next, so each season’s requirement needs to be applied each year regardless of price. With that in mind, there are options and strategies to employ to make each unit of applied nitrogen more efficient and economical.
Rotation: Corn following a rotation of a legume (soybean, alfalfa) or other low residue crop typically requires less applied nitrogen due to the soil’s ability to provide more mineralized nitrogen to the corn crop during the growing season. Taking advantage of the mineralized nitrogen can often reduce applied nitrogen from over 50 to 30 lbs. of N. This is often the easiest way to gain additional “free” nitrogen from existing soil nitrogen sources.
Split application: Nitrogen is a macronutrient that can easily be lost due to leaching or denitrification, most often due to excessive moisture in the soil profile. Therefore, by delaying part of the nitrogen application to late spring or early summer, the nitrogen is not exposed to potentially wetter early spring soils and heavy precipitation events and is applied when the crop is actively taking up the nutrient. Thereby reducing the time the nutrient is sitting in the soil subject to loss. In many cases, overall lower rates of nitrogen can be applied because the uptake efficiency is increased.
Stabilizers: Nitrogen stabilizers help prevent loss due to denitrification, leaching, and volatilization. The two main types of stabilizers are nitrification inhibitors and urease inhibitors. Urease inhibitors protect from ammonia volatilization. Nitrification inhibitors stop or slow the nitrification process, keeping the N in the NH4+ form longer, which protects it from leaching and denitrification losses. Stabilizers can be utilized in both pre-plant and side-dress applications.
Manure: Manure can be an excellent source of slow release nitrogen and may be more available and possibly less expensive than commercial sources of N. If using manure, be sure to know how much total nitrogen is available and how readily it will be available during the current growing season.
Nitrogen source: There seems to be widely varying price ranges for different sources of nitrogen, such as anhydrous ammonia, urea, or urea ammonium sulfate solution (UAN). If possible, use the most economical source in the area.
Nitrogen Calculator: With high nitrogen costs and high commodity prices, finding the most “economical” rate may be different than what has been applied in the past, particularly when prices with the source of nitrogen varying so much. The nitrogen rate calculator (http://cnrc.agron.iastate.edu/) can be a very useful tool in this exercise. The price of N and expected corn sales price can be inputted to find the most economical nitrogen rate (EONR).
In summary, nitrogen by far can be the most important nutrient in terms of obtaining maximum yield potential. Yet this year it may be one of the highest priced inputs in corn production. So, getting the rate “right” is extremely important yet very challenging at the same time. Utilizing all tools available to find that sweet spot will hopefully help to produce the most efficient use of applied and soil available N while minimizing costs.
Corn nitrogen rate calculator. Iowa State University. http://cnrc.agron.iastate.edu/.
Website verified 4/26/22
ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.
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