Now Is the Time to Prepare for Fertilizer Applications

Sep 27, 2024

By Angie Rieck-Hinz

Just as taking good quality soil samples is important for making nutrient application recommendations, so is managing application rates and distribution of dry nutrients and lime. This also holds true for anhydrous ammonia applications and applications of solid and liquid manure but this article will focus on dry fertilizer application.

Under-application of dry fertilizer or lime that does not meet the required application rate recommendation can often cause a negative impact on crop yields. Over-application of nutrients can cause excess input costs. These misapplications can be caused by uneven distribution of nutrients. Often, we notice under-application in fields when we see “yellowish” repeating streaks in the field, usually in the spring. Distribution issues are more evident today with more widespread adoption of aerial imagery with drones. This issue is more important with non-uniform application and under application of nitrogen (N) applications, than phosphorus (P), potassium (K) or lime, but all are crucial for crop production. N and sulfur (S) streaks in fields are the most noticeable. You will rarely notice symptoms of over-application in the field.

What causes uneven distribution of dry products?

There are many factors that lead to uneven distribution of dry products, including poor adjustment of the application machine; fertilizer quality, including shape, size, density, and hardness; and improper swath width and lack of calibration.

What can the retailer/applicator do to mitigate these application and distribution issues.

These factors should be addressed by the retailer for each product, each year, and for major application rate changes and when product conditions change. One example of a change in product condition is when you get to the bottom of the pile and there is more product with a smaller size, or the shape has been changed as product is constantly scooped, pushed and loaded; in other words, there are more “fines”. Fines can reduce the width of spread patterns.

Pattern calibration tests should be conducted for all types of application equipment, including spinner spreaders and pneumatic or air spreaders, so the applicator understands spread swath and particle distribution and adjustments to swath width can be made as needed.
Product quality should be analyzed. Particle density and hardness can greatly impact particle size as it comes off the spinners, which consequently impacts spread swath.
Don’t forget about the wind. Good fertilizer application depends on getting the right rate in the right place. Modifying direction or recalibrating the spreader can help to mitigate movement of particles by the wind. Not applying on windy days also makes sense.

What can farmers do to mitigate these application and distribution issues?

Farmers rarely apply dry fertilizers and rely on their agricultural service providers for such applications. In this case communication is key to alleviating future issues.

If you are seeing similar patterns of streaks or shorter crops in fields, or your yield monitor is indicating such patterns, consider asking your retailer to change the application pattern. Instead of applying north-south, perhaps change to east-west or vice versa.
Consider asking for products to be applied separately. Due to fertilizer particle size, shape and density, products applied with a spinner-spreader do not distribute evenly. To achieve uniform distribution, it may be worth the effort to apply the products separately.
Know your soil test numbers. If your soil tests are in the optimum or higher categories, the impact of poor spread patterns for P and K may not be as crucial if soil test levels are low or very low and fertility can be yield-limiting.

In summary, good fertilizer application and distribution is important to minimize yield loss in the field. Equipment calibration and product quality evaluation help to identify where adjustments can be made to maximize return on investment for your fertilizer dollars.

Source : iastate.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.