The amount of nitrate and sediment seeping into large streams and rivers from agriculture can be drastically reduced by creating wetlands along waterways, researchers at the University of Kansas found
Excessive nitrate or sediment levels can affect local fish populations and increase drinking water treatment costs.
The pollutants also make their way into water bodies downstream such as a reservoir or the ocean, creating algal blooms or hypoxic or “dead zones.
” According to the researchers, the dead zone in the northern Gulf of Mexico is directly related to nitrate coming from the watershed.
of the Mississippi. They compared different approaches to improving water quality, such as reducing runoff from farms and adding wetlands, then gauged the economic costs of each.
Because most methods rely on voluntary participation from individual farms and are performed by a patchwork of different agencies, the researchers found they tend to be less effective.
“Currently, there are individual management or conservation practices, including ground cover, high-precision fertilization, reduced tillage, landscaped wetlands and canyon tip management.
Those are some of the different practices we considered,” said lead author Dr. Amy Hansen. non-point resources is voluntary in the US through incentive programs, and the scale at which these conservation practices are often considered is the individual farmer, when a coordinated approach is much more effective.
“In a sense, it’s like a recycling program where you say: “Anyone who recycles one thing is better than recycling no one.” This is true, some recycling is better than no recycling, but a coordinated approach saves money and becomes more effective.
” The team found that engineered wetlands are most effective, especially when size and location are assessed on the scale of a watershed – a entire region that flows into a common waterway.
This is because wetlands both slow water down as it flows into streams and rivers, and contain vegetation and microbes that can process nutrients that are used as fertilizer for crops.” Microbes and plants in wetlands actually remove the nitrate from the water,” Hansen said.
“With sediment, on the other hand, what the fluvial wetlands do is hold back the water during these high currents — and by holding back that water, you get lower peak currents, reducing the amount near channel sediment transported downstream.
” The researchers used Southern Minnesota’s Le Sueur River Basin as a proof-of-concept watershed, but say their findings could be applied to agricultural areas in the US Midwest.
9breaking has previously looked at the increasing popularity of wetland restoration projects as a way to mitigate climate change and create a home for various types of wildlife.