Losing Topsoil? Plant Switchgrass.

Joanna Schroeder

Switchgrass, an energy feedstock that can be used for biofuel production, now has another benefit: it can improve soil quality and can be grown on farms that have lost fertile topsoil. According to new research from the University of Missouri (MU) College of Agriculture, Food and Natural Resources has found that switchgrass may be a promising option for growers who have challenges with growing other crops; that is, if there is a good market for the crop. The study was published in a recent edition of the Soil Science Society of America Journal.

The MU researchers studied plots with varying amounts of topsoil. Each plot included corn, soybeans and switchgrass. They found that switchgrass grew well in areas without topsoil and actually improved the soil in those areas.

“Once a farm loses its topsoil due to erosion, the soil recovers very slowly,” explains Stephen Anderson, the William A. Albrecht Distinguished Professor of Soil Science at MU. “Switchgrass can be grown efficiently on eroded claypan soils; farmers who have lost their topsoil may want to consider growing this hardy plant. Switchgrass can be harvested and sold as a biomass crop for ethanol production or as fuel for power plants. While demand depends on the current market for biomass crops, this could be an answer for these farmers who otherwise have challenges obtaining good economic returns growing grain crops on eroded land.”

The research looked at several farming plots with varying levels of topsoil. The plots were established in 2009 and each plot ranged from extra topsoil to no topsoil. According to lead author Syaharudin Zaibon, a doctoral candidate at MU, corn, soybean and switchgrass were grown on each plot for five years. After this timeframe, the researchers looked at the soil density and water permeability of each plot. What was discovered was that the plots that grew switchgrass had improved soil quality with little or no topsoil on which it grew.

“Claypan layers have lower water permeability, making it more difficult for plants to receive water and for farmers to obtain good economic returns from grain crops when the silt loam topsoil is lost from these areas,” Anderson said. “This lower permeability prevents oxygen and water from seeping into the eroded soil. We found that over a number of years, the switchgrass was able to increase, or improve, the water permeability into this eroded soil, leading to an 11 percent higher water saturation than the areas where corn and soybeans were grown. This study shows that not only can switchgrass grow in these eroded claypan soil areas, but it actually can improve the soil over time, potentially opening the door for better production of grain crops subsequently grown in those areas.”

advance biofuels, Farming, feedstocks, Research