High Fertilizer Prices Suggest Reconsidering Application Rates

Apr 02, 2026

By Nick Paulson and Gary Schnitkey

The ongoing conflict with Iran has resulted in significantly higher nitrogen fertilizer prices as damaged energy infrastructure and closure of the Strait of Hormuz has created supply chain bottlenecks (see farmdoc daily articles from March 17, March 23, March 24, and March 27, 2026). Nitrogen fertilizer prices have been slowly increasing since the fall, but those increases have escalated sharply since the conflict began. Price increases since late February have ranged from 20-25% for anhydrous ammonia to more than 40% for urea at locations in the Corn Belt region of the US (see slides and video from farmdoc webinar on March 26, 2026) .

Corn prices have increased as well but not as much as fertilizer prices. As a result, recommended nitrogen application rates are lower under current pricing conditions compared with last fall. For farmers who apply a portion of their nitrogen in the spring, reducing remaining nitrogen applications to be more in line with the Maximum Return to Nitrogen (MRTN) rate recommendations would be highly advised to avoid unnecessary costs and maximize returns. This is particularly true for situations where spring nitrogen needs were not priced prior to the price increases experienced since the start of the conflict in Iran.

What is the MRTN?

The MRTN calculator was developed and continues to be maintained by University soil fertility specialists from states in the Corn Belt region of the US. The calculator uses results from research trials and provides rate recommendations which maximize the economic return to nitrogen. The recommendations are specific to location or region, crop rotation, and the prices for both corn and nitrogen. Users can use the calculator to provide a recommendation based on a single set of prices or use the multiple price mode to look at different scenarios for corn and nitrogen prices to compare recommendations.

For Illinois, N rate recommendations are provided for three regions (northern, central, and southern) for corn following soybeans and for two regions (northern and central) for corn following corn. The rate recommendations will also vary based on the prices provided by the user for corn and nitrogen.

Four common nitrogen fertilizer products can be selected with prices for those products entered as quoted and then converted to $/lb of N by the calculator. Users can also enter prices in $/lb of N directly.

Based on these inputs, the calculator provides a recommended rate – the MRTN – that maximizes the farmer’s return to nitrogen. It is also important to note that the MRTN recommendation accounts for all potential sources of applied nitrogen. Producers should consider the nitrogen contributions from other sources such as manure, DAP, and MAP. Higher nitrogen prices will result in lower MRTN rates holding the corn price constant. Higher corn prices will result in higher MRTN rates holding the fertilizer price constant.

Source : illinois.edu

Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.

High Fertilizer Prices Suggest Reconsidering Application Rates

What is the MRTN?

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Video: Turning Plant Defense Into a Management Strategy

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