The Impact of Residue on Soil Erosion: SNIRT in the Red River Valley!
Did you know it’s estimated that we still lose 3-5 tons per acre of productive topsoil to wind erosion every year in the Red River Valley? 5 tons per acre equates to about the thickness of a dime.
You might say it doesn’t sound like a lot, but over time it adds up.
We are talking about the richest, most productive soils at the top. It’s a silent productivity killer that we need to pay a lot more attention to if we want to maintain the long term productivity of our soils.
As agronomists and farmers, we closely monitor the spring thaw looking for insights into how the next growing season is shaping up. Will it be an early or late start? Are field conditions going to be wet or dry at planting time? What do moisture reserves look like? .
With the snowpack melting quickly, we are already noticing large patches of exposed black soil. While this might seem like an early sign of spring, it also raises the potential risk of losing more precious topsoil to wind erosion.
One of the most striking observations this year is the presence of SNIRT — a mix of snow and dirt accumulating in ditches and along field edges. This is the time of year where the black and white contrast is especially noticeable. Driving through the countryside you can really see which fields are most at risk and it’s almost always tied to residue levels. Without the protective layer of plant material, the exposed soil is easily lifted and carried by the wind, leading to increased soil loss and reduced field productivity.
Early snow melts expose vulnerable soils to freeze-thaw cycles that break down aggregates into finer particles and dust which are in turn more susceptible to erosion.
Conversely, fields with a good amount of residue left from the previous season are seeing more snow pack and less risk of soil movement. The leftover plant material acts as a protective barrier, helping to anchor the soil in place and reducing the impact of wind erosion.
Why is Leaving Stubble Over Winter Important?
Leaving stubble in the field over winter plays a critical role in preventing soil erosion. Here’s why:
- Wind Protection: Stubble creates a natural windbreak at the soil surface, slowing down wind speeds and reducing the amount of soil that gets lifted and blown away.
- Soil Structure Preservation: Residue helps maintain soil integrity by preventing the breakdown of soil aggregates, which are essential for water retention and aeration.
- Moisture Retention: Stubble traps snow, which helps retain moisture in the soil for spring planting. Without it, fields can become excessively dry and prone to further erosion.
- Nutrient Cycling: As the residue decomposes, it returns essential nutrients to the soil, improving soil health and fertility for the next crop.
Looking ahead, if we do not receive more snowfall to cover these exposed fields, we can expect soil to continue blowing until the next crop establishes. This could result in significant topsoil loss, decreased seedbed quality, and potential impacts on early crop emergence.
What Can Be Done?
- Residue Management: Leaving adequate crop residue on the field post-harvest can significantly reduce the risk of soil erosion.
- Cover Crops: Implementing cover crops can help protect soil, improve organic matter, and reduce wind erosion.
- Windbreaks: Utilizing shelterbelts or standing stubble can slow wind speeds and minimize soil movement.
- Snow Retention Strategies: Practices such as strip cropping or leaving stubble standing can help retain more snow, providing moisture and protection for the soil.
Too much of a good thing?
Too much of a good thing isn’t always a good thing! Our flat fields and heavy clay soils are notorious for holding on to moisture. This can create a lot of residue which when left on the surface keeps it from drying out and warming up in the spring. Our growing season is short enough and any delays in planting usually means lower yields. It’s always a fine line between leaving too much or too little residue on the surface.
This is why we are always evaluating new products and practices, looking for ways to help our clients make better decisions. This season we will be looking at various biologicals in our research trials that help break down heavy residues and improve nutrient cycling. If we can better manage residue by adopting practices less destructive than deep tillage, we will be making progress on many fronts.
Soil is one of our most valuable resources, and protecting it from erosion should be a priority for all growers. If you’re noticing SNIRT in your fields, consider how residue management can play a role in preventing further soil loss. Let’s work together to keep our fields productive and sustainable for years to come.
