Refining nutrient management for cold climates
Wisconsin Dells — When it comes to soil health and protecting the environment, farmers need to look at the big picture.
Dr. Don Flaten, professor of Soil Science at the University of Manitoba, Canada, told about 200 people attending the Discovery Farms conference in Wisconsin Dells that in the quest for continual improvement in phosphorus management, it is important to diagnose the cause before selecting a solution. He stressed that there is no “one-size-fits-all” way to deal with the issue.
“Everyone — small farmers, big farmers, city people — are contributors to environmental problems, Flaten said. "There is a lot of finger pointing but we need to look at the big picture.”
He commended the Discovery Farms program for their work on real farms with real-life situations.
“Models don’t always work," he said. "They must be validated in real-life situations and on real farms.”
As an example, Flaten pointed out that laboratory testing may show buffers will keep phosphorus from entering waterways from nearby fields. While they may help in some cases, he said buffers are dormant or dead and do not take up phosphorus when melted snow sits on them or runs across them.
In Manitoba, snow melt contributes significantly to problems with phosphorus in water, particularly Lake Winipeg. Most of the farming country is flat and dry and snowmelt contributes to 80 percent of the loss of phosphorus.
“We see a lot more dissolved phosphorus in snowmelt than we see in summer runoff," Flaten said. "Erosion is not our problem.”
When erosion is the problem, conservation tillage or no till may be the solution, but there are cases where it may not be the best management practice.
“Water management practices that allow nutrient-rich snowmelt runoff water to be retained and used upstream in our watersheds show considerable promise for reducing phosphorus loss from farms in this region,” he said.
In the Manitoba area, holding ponds have worked well for collecting snow melt and excess rainwater. Farmers then pump the water from those ponds and irrigate their surrounding fields with it during a time of the year when the phosphorus and other nutrients can be used by the crop.
Flaten concluded by pointing to another issue when evaluating any potential best management practice for a region.
“Phosphorus loss is only one of many worthwhile objectives for improving agricultural sustainability and environmental protection,” he notes. “There are many benefits for conservation tillage, perennial forages, cover crops and vegetative buffers that deserve consideration as offsets for the increased risk of phosphorus loss.”
He commended all the efforts to concentrate applied fertilizer in just the areas where it is needed. Flaten also pointed out that farmers cannot stop applying fertilizer if they are exporting nutrients off the farm in the form of meat, milk or cash crops.
Look at the big picture
"We can’t mine the soil, and farmers understand that," Flaten said. "Legislators, however, do not understand that.
“Manitoba’s rule prohibiting any spreading of manure in winter has put a lot of small farms out of business because they can’t afford manure storage.”
He suggested looking at environmental health as we look at human health. Before dealing with a health issue, there must be an exam and a diagnosis.
“You can’t just assume everyone has high blood pressure and treat everyone for that," Flaten said. "Using a knife in surgery and getting knifed in the back in a dark alley of a city utilize the same tool but with very different results.”
As farmers strive to improve the overall health of the environment, they need to be more broad-minded and smarter about the implementation of beneficial management practices. The first step is to invest more effort into assessing each case individually and comprehensively to diagnose the real cause of the problem. Then, just like dealing with a human health issue, choose the right treatment, considering the best possible results and all of the risks of unintended side effects.
An important requirement for a comprehensive approach is to ensure that nutrient management and water quality research is developed and evaluated in real watersheds and on real farms, Flaten said, not just in a laboratory or computer model.