The Relationship Between Spring Moisture and Nitrogen Loss

Changing climate patterns and wet springs are becoming increasingly common. With warmer springs bringing above-average rainfall, farmers face greater challenges in accessing fields for planting. More critically, many farmers are concerned about soil nutrient content and the risks of nitrogen leaching and runoff.

Springtime often brings unpredictable rainfall, significantly impacting soil water movement and nutrient dynamics, particularly nitrogen levels crucial for crop health. 

Consequently, managing nitrogen in response to spring rainfall is essential to maximize crop yields and maintain soil health.

What’s the Impact of Spring Rainfall on Nitrogen?

Spring rainfall plays a pivotal role in crops, replenishing soil moisture levels and kickstarting the growth cycle. However, wet conditions in the spring pose significant challenges for nitrogen management. 

Nitrogen, a vital nutrient for plant growth, is highly soluble in water. This makes it susceptible to displacement during heavy precipitation. While spring rainfall combined with cooler temperatures can sometimes reduce nitrogen loss, warmer temperatures, which have become more common recently, increase the risk of nitrogen runoff and leaching, especially when rainfall is poorly timed or excessive. This loss not only affects soil fertility—but also jeopardizes crop yield and quality.

Most inorganic nitrogen in the soil is in the form of nitrate. Nitrate is highly mobile and subject to leaching losses when excess water drains below the active root zone. For example, one inch of rain can move nitrogen about a foot deeper in sandy soils. After receiving four or more inches of rain, much of the applied nitrogen may end up four to five feet deeper than the root zone of most crops, severely limiting significant nutrient uptake. 

This displacement of nitrogen not only leads to inefficiencies in fertilizer use but also poses environmental risks, such as waterway contamination and eutrophication. To mitigate these issues, farmers need strategies to improve nitrogen retention, like: 

• Nitrogen stabilizers, which can help keep nitrogen in the soil longer by slowing down its conversion rate from ammonium to nitrate

• Implementing split applications or fertigation

• Employing cover crops 

For split application and fertigation users, precision agriculture tools like N-Time can provide real-time monitoring and control over nutrient delivery to ensure optimal uptake by plants and minimize environmental impact.

Applying Additional Nitrogen

You may wonder, “Should I apply extra nitrogen if we’ve had excess rain after I already made nitrogen applications?”

The answer depends on four factors: 

1. Nitrogen form: If you applied fall or spring nitrogen using a nitrification inhibitor and anhydrous ammonia, the nitrogen should still be available in the NH4+ form. This form is less susceptible to leaching, so it remains bonded to the soil regardless of excess moisture. 

However, if you used UAN (urea ammonium nitrate), it’s likely about 25% of that applied nitrogen is already in nitrate form. That makes it highly prone to leaching—and you’ve likely lost it with significant rainfall. The remaining 75% of the nitrogen in UAN is in the form of urea and ammonium (NH4+), which are less susceptible to immediate leaching, especially if a stabilizer was used. 

1. Soil type: Sandy soils are more prone to leaching compared to clay or loam soils due to their larger pore spaces and lower water-holding capacity. Farmers with sandy soils need to be particularly vigilant about nitrogen losses following heavy rains. 

1. Soil temperature: Warmer soil temperatures accelerate microbial activity, which increases the rate at which ammonium converts to nitrate. In wet conditions, nitrate can be lost through leaching or denitrification. Conversely, cooler temperatures slow down these processes, helping nitrogen stay in ammonium form for longer periods.

1. Total rainfall: Rainfall amounts and distribution over time are crucial. A sudden deluge can cause immediate runoff and leaching, whereas consistent light rainfall over a longer period may allow more nitrogen to be absorbed by plants and soil microorganisms.

To assess whether additional nitrogen is necessary after heavy rainfall, soil testing for nitrate levels can indicate how much nitrogen remains available for crops. If tests show low nitrate levels, a supplemental application of nitrogen may be justified.

Precision agriculture tools, such as soil moisture sensors and remote sensing technologies like N-Time, can help you make more informed decisions by providing real-time data on soil and crop conditions.

How Sentinel Fertigation Helps Solve the Nitrogen Problem

To limit losses and mitigate spring rainfall’s potentially harmful impacts to nitrogen availability, you need to ensure optimal nutrient uptake by your plants. 

For this, you need real-time monitoring and control over nutrient delivery. That’s exactly what we offer at Sentinel through N-Time: a cutting-edge tool designed to measure the amount of nitrogen in a field and determine optimal timing and quantity of fertilizer applications.

N-Time uses readily available satellite imagery and data analytics to continuously monitor soil nitrogen levels and crop needs. By leveraging this data, N-Time can dynamically adjust nitrogen applications to match the specific conditions of each field, taking into account factors such as soil type, temperature, and recent weather patterns. This tailored approach helps prevent over-application and runoff, reduces environmental impact, and improves NUE (nitrogen use efficiency).

The benefits of N-Time extend beyond simple nitrogen management. By optimizing nutrient delivery, N-Time:

• Supports healthier crop growth, leading to improved yields and better-quality produce 

• Helps maintain soil health and sustainable farming practices

• Allows farmers to reduce overall fertilizer use, resulting in significant cost savings

The Bottom Line:

Changing climate patterns and increasingly wet springs pose significant challenges for farmers, especially with nitrogen management. With heavy spring rains causing potential leaching and runoff, it’s become more complex to maintain soil nutrient content and ensure optimal crop health. Innovative solutions like N-Time offer a promising way forward. 

For questions about spring nitrogen or N-Time, reach out to us at Sentinel Fertigation.