Modern agriculture’s large mono-culture fields grow a lot of corn and soybeans, planted annually. The outputs from row crops can be measured both in dollars paid in the market and also in non-market costs – known as externalities. Soil, nutrients, groundwater, pollinators, wildlife diversity and habitat -- among other things -- can be lost when crop yields are maximized.
It appears prairie strips have an extraordinary power to change that pattern. A prairie strip is much what it sounds like – a strip of diverse herbaceous vegetation running through a farm’s row crops. In the Midwest chances are the soil that now supports crops was once covered in prairie before cultivation. Prairie plants are a mixture of native grasses, wildflowers and other stiff-stemmed plants. They have deep roots that draw water and nutrients from far below the surface. They are perennials, returning to grow each spring.
“Research shows that areas of native prairie planted in the right places in a farm field can provide benefits that far outweigh losses from converting a small portion of a crop field to prairie,” said Lisa Schulte Moore of Iowa State University. “For example when we work with farmers to site prairie strips on areas that were not profitable to farm, we can lower their financial costs while creating a wide variety of benefits.”
Schulte Moore is a team member with Science-based Trials of Rowcrops Integrated with Prairie Strips -- or STRIPS. The program helped to discover that converting 10 percent of a row-cropped field to prairie strips has several benefits.
It reduces soil loss by 95 percent.
It reduces overland water flow by 37 percent.
It reduces the loss of two key nutrients -- nitrogen by 70 percent and phosphorus by 77 percent.
It leads to greater abundance and diversity of beneficial insects, pollinators such as bees and monarch butterflies, and birds. Going from zero to 10 percent prairie provided far more than a 10 percent increase in measured benefits.
“Some of these benefits can impact our pocketbooks but are not accounted for by typical financial markets,” Schulte Moore said.
Those include ecological benefits such as flood control, cleaner water and storage of carbon from the atmosphere. Market benefits also exist. More productive soil in the fields can translate into better yields, fiber and honey production, forage for livestock and hunting leases.
The Science-based Trials of Rowcrops Integrated with Prairie Strips research began in 2007 in Iowa. Because of promising scientific results, five years later the researchers began working with farmers to introduce prairie strips onto commercial farms. While the research results have been more variable in those more-complicated settings, the findings are encouraging. Cooperating farmers say they like what they see.
The plantings require a modest investment in site preparation and seed planting. Maintenance tasks include some mowing in the establishment years and spot treatment for weeds. So far researchers haven’t seen competition between the prairie plants and crops that impact yield.
But lack of stable financial rewards for establishing and maintaining prairie strips is a barrier to widespread adoption.
“Finding ways to return economic value to farmers and farmland owners is crucial,” Schulte Moore said.
She’s now focused on developing marketable products from prairie strips – such as renewable-energy sources from prairie biomass. That would help change what’s already a solid investment into a can’t-lose proposition.
Schulte Moore presented the research at the November 2018 meeting of the American Society of Agronomy and Crop Science Society of America in Baltimore, Maryland. The research has been funded by a consortium.
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