When I first moved to North Carolina, I was surprised farmers were still allowed to burn wheat fields, especially in places where neighborhoods were close. That was twenty-some years ago. Even in the mid-90s, there was a growing group of people concerned with adding more greenhouse gases into the air.
Burning is a management tool that has merits and under some conditions might be the best treatment for certain places. Ridding fields of noxious weed seed is just one advantage, but to a degree it’s overrated. Weed seed under the insulation of soil is likely unaffected.
Insects are partially controlled, but many lay eggs below the soil surface and they might not be killed. This is especially true when the burn spreads rapidly.
Burning removes the material responsible for holding the soil, so planting soon after the burn is important. Phosphorus is a nutrient that is not lost by burning. It might even be made more available. However, if ash residue is blown away it will be lost.
No knowledgeable person would ever argue that control burning is not an important forest management practice. Keeping levels of readily ignitable fuel at low levels is critical for reducing the number and severity of wildfires. Much of the fire problems in California could have been averted if more of this was done.
This method is not a panacea though. Disadvantages to burning include lowering of long-term natural fertility, increased cost of production, less water retention, greater liability risk and possible health concerns. Farms aren’t as isolated as they once were, so fields are in closer contact to residential areas.
There is somewhat less burning than there once was, as no-till planting has become more popular. Drilling into existing stubble means fewer trips across the field. That saves energy and money.
Yield differences are likely insignificant despite what proponents of each method espouse. I’ve seen data showing increased yields planting into stubble and I’ve seen studies that show no difference.
I’ve also seen inconsistent stands of soybeans, because of differences in stubble density. This probably caused seeds to be sown at different depths. Also, some farmers don’t have no-till equipment, so it’s a moot point to them anyway.
So, if we assume that the practice of burning wheat fields will continue, how can we make it safer? We need to pay attention to the weather. High temperatures, low humidity and high winds are all factors that contribute to fires getting out of control. So is not enough labor to do the job safely.
Paying attention to wind direction is critical. So is keeping the edges of the field clean and free of highly combustible materials. Burning a border against the wind can be a slow process, but it will prevent a raging fire from going where it shouldn’t.
I think burning fields will always be controversial. I further agree that it might not always be the best method for field preparation. This is particularly true as homes continue to encroach on farms, but burning is still a good tool to keep in the toolbox.
Ted Manzer teaches agriculture at Northeastern High School.