Most row crops require nitrogen (N) and phosphorus (P) to get an adequate supply of nutrients and maximize yield. Soybeans are no different, requiring both N and P to grow, but the application of these fertilizers could have negative effects on the environment.

Researchers continue to look for ways to help farmers apply these and other nutrients without the environmental impact.

“While soybeans require substantial amounts of nitrogen and phosphorus for crop production, these nutrients could enter the environment and impact the water or atmosphere,” says University of Minnesota Assistant Professor Fabian Fernandez, Ph.D.

In a webcast from the Plant Management Network Fernandez offers practices to help.

Additional N not needed

Soybeans have the ability to fix their own N in the soil, so applying additional N does not usually benefit the crop. Fernandez has studied the benefit of applying N to soybeans at different growing stages and found that it does not increase yields.

Reducing the loss of P

Phosphorus is another important nutrient for soybeans, but soil erosion causes major losses. Fernandez says P is usually found in higher concentrations at the surface layer of the soil, which is the same layer where most erosion loss occurs. Minimizing the possibility of erosion will help keep P in the soil.

Other practices

Fernandez offered these additional tips that may be beneficial to reducing the loss of N and P:

  • Cover crops
  • Crop rotation
  • Buffers, bioreactors and wetlands
  • Testing soil-nutrient levels to help you apply nutrients only in the amounts they’re needed

Environmental impacts

N and P can be harmful to the environment in a variety of ways, including:

Surface water: N and P can cause pollution of surface water. Runoff of these nutrients into bodies of water can support algal blooms, which can deplete oxygen levels in the water, making it unable to support fish and other aquatic life.

Ground water: N can be leached into the ground water as nitrate, impacting water resources that many Midwestern communities use for drinking water.

Air pollution: N can enter the atmosphere as nitrous oxide emissions that occur during wet soil conditions and contribute to greenhouse gases.

The soy checkoff sponsors the “Focus on Soybean” webcasts through a partnership with the Plant Management Network, making the videos free for U.S. soybean farmers to watch.