The Regenerative Approach to Nitrogen

With sky-high nitrogen prices, is there a way to spend less on nitrogen while still getting great crop performance?

The answer is a resounding YES. You can do so with a stable, slow-release, regenerative approach to nitrogen management.

Many growers are familiar with the “4 R’s” of Nitrogen management: Right Source, Right Rate, Right Time, and Right Place. In this article, we’ll describe how AEA interprets those 4 R’s, and how our Nitrogen Efficiency Program helps growers spend way less on nitrogen. 

Right Source: ​​Not all forms of nitrogen are created equal. 

Each source of nitrogen is used differently by plants and soil biology. Each form of nitrogen produces different crop responses from the others. It’s important to understand the differences. Here are the four main forms of nitrogen, listed in order of decreasing efficiency.

1. Protein nitrogen is the ideal and most efficient source of nitrogen. Microbial populations fix atmospheric N and process it into amino acids and proteins in the soil, which can be absorbed directly by the plant. Because microbes have done all the work of complexing the nitrogen, the plant saves loads of energy from doing it itself. Such biologically-complexed nitrogen is integral to a regenerative approach. Soils with high microbial activity often require only a fraction of the applied N to produce an equivalent crop response as soils with low biological activity.
2. Urea is the second most efficient form of N. While it seems more expensive, the per-unit cost of urea is balanced by the fact that much less plant energy and water is required to convert it into complete plant proteins than other synthetic forms. It is also relatively gentle on soil microbes. To further maximize urea N, dry urea can be liquified on the farm. Liquid urea can then be combined with nitrogen efficiency-enhancing materials like molybdenum and humic substances, and applied in multiple smaller shots, rather than larger amounts less frequently, which is almost always less efficient.
3. Ammonium is the third most efficient form of nitrogen for crop metabolization. NH4 fertilizers saturate the market, including dry ammonium sulfate and liquid UAN 28% or 32%. Application rates of soluble ammonium N that are higher than what a crop can immediately use will benefit from the addition of molybdenum and humic substances to extend its plant availability and buffer negative results to soil biology.
4. Nitrate is the least efficient form of N for crops to metabolize, even though it’s the fastest to be absorbed. Plants use a significant amount of their photosynthetic energy to convert nitrates to amino acids and proteins. If you’re using nitrate, it is crucial to maximize your nitrogen efficiency practices. Molybdenum is the critical enzyme cofactor of the nitrate reductase enzyme, which is responsible for converting nitrate into plant and microbial proteins. Humic substances can be employed to slow the rapid release of nitrate into soil systems.
   

• • A note on sulfur: Nature maintains a balance of 10 parts nitrogen to 1 part sulfur. Disturbing that balance results in loss of biology, carbon, and nitrogen. It is important to always include a minimum of 1 part sulfur for every 10 parts nitrogen being applied.

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Right Rate & Right Time are inseparable

Never apply more nitrogen than plants can use before it is volatilized, compounded, or washed away.

Time your nitrogen availability to match the plant’s demand based on its growth phases. This means there is a tight window for N applications. Input savings and crop quality gains can offset the investment in equipment modifications or purchases needed to better time N applications.

More nitrogen is required during vegetative growth phases, while excess nitrogen is highly undesirable for seedlings or senescing plants. 

A corn crop is able to access adequate biological nitrogen even in relatively poor soils until V4-V5. Winter wheat grows fastest in mid-spring—that’s when to apply N, not in fall or winter.

Right Place: The crop itself

The right place for nitrogen is in the crop itself. Use any uptake pathway that makes sense for your operation if it gets N right into the plant. These include dry and liquid soil applications, foliar applications, side-dressing, biological uptake from nitrogen-fixing bacteria, fungal activity, release from soil organic matter, and crop residues. 

The best temporary home for soil-applied nitrogen is in living microbes. Diverse populations of microbes in the immediate vicinity of applied N can mop up excess nitrogen and prevent it from being lost to the atmosphere. They’ll store it and release it to roots later. Nitrogen compounding products can help with slow and steady release of early applications.

It’s best not to apply all of your nitrogen to the soil itself as a preplant or at-planting operation. Side-dressing or fertigation of nitrogen later in the season provides the opportunity to use the 4R’s to best advantage by supplying N when and where needed—to the roots when plants are at their maximum of vegetative growth.

Next Monday, we’ll get into the details of AEA’s Nitrogen Efficiency Program, which helps growers reduce nitrogen usage and save money.

If you can’t wait that long, you can download our Nitrogen Efficiency Booklet: