Growing deep-rooted prairie plants can create soil with better drainage and a better ability to provide plant-available water
Reconstructed native prairies may offer an ideal crop for biofuel feedstock. Prairie plants could be grown alone or in rotation with row crops — allowing farmers to enjoy the benefits of either system.
Deep-rooted prairie plants create healthier soil, rich in organic matter, with plenty of aeration, good infiltration, stable structure and active nutrient cycling. These organic-rich soils hold more water and create a reservoir plants can draw from in times of drought.
Growing up in a rural farming area in Panama, University of Alberta soil scientist Guillermo Hernandez become very well versed in the principles of drought resistance, in particular, environmental factors driving water use efficiency in plants.
“Adaptation is key to designing and implementing successful biomass production systems for the present and future,” said Hernandez. “As plant species are more resistant or tolerant to drought effects that occur in water deficit regions of North America, they’re likely to prosper under extreme weather fluctuations, including erratic rainfall patterns.”
Hernandez believes harvesting native prairie plants for bio-energy has many potential advantages, but also some possible downside. For one thing, “We don’t know what long-term biomass removal will do to wildlife that will depend on these reconstructed prairie ecosystems.”
Hernandez says more studies examining all potential ecosystem services are needed. “Renewable energy and carbon neutrality are great advantages of biofuel systems, but we still need to focus on several aspects of how to sustainably manage these systems.”
“Soils with good structure will drain excess water more easily and store more plant-available water,” says Tom Sauer, a soil scientist with the United States Department of Agriculture (USDA). “Tillage and erosion tend to destroy soil structure and reduce the amount of soil organic matter.
“This results in many of our cultivated soils now having poor natural drainage and less ability to supply water to crops. To make our cropping systems more resilient and less susceptible to drought we need to reverse decades-long practices of excessive tillage and erosion.”
Sauer sees a clear solution. By restoring good structure and increasing soil organic matter, we can make our soils much more efficient in supplying water to crops.
Besides restoring soil structure, some crops can benefit the soil surface.
“Bio-fuel crops in semiarid areas that are perennials and provide ground cover to protect the soil surface may be able to be managed to reduce runoff and erosion, saving more water for plant uptake.”
Growing these crops would eliminate the need for tillage, reversing soil degradation and improving soil quality. Sauer says, “The soils would then become better at not only reducing runoff but also at removing contaminants that infiltrate with the water.”
According to Sauer, some changes in surface hydrology may occur, “Especially reduced stream flow if these crops use more water than the current land use and have less runoff and less percolation through the root zone.
“Such perennial systems are likely to be much more resilient to climate change and to potentially greatly improve soil quality, especially of degraded soils.”
These patterns should be considered when designing new land uses as, for instance, rainfall amounts and distribution could be different one or two decades into the future. If we can anticipate these trends we can initiate a cropping system that’s better adapted to the changing future climate.”
Sauer said this may be the most challenging part of changing land use. “To maximize the benefits of a return to prairie, one can’t rotate crops in using tillage, as the disturbance will undo much of the improvements in soil quality derived from the prairie.
“It may be possible to use no-till crop production practices in rotation with prairie, but establishing and maintaining prairie is expensive.” †