New methods can increase crop sustainability and reduce water pollution as world-wide demand for food grows.
Nearly 40 percent of the world’s land is devoted to farming, a figure that will need to increase dramatically as the Earth’s population grows from its current count of 7.5 billion to nearly 10 billion by 2050.
Humans have been managing crops for thousands of years — you would think we would have farming mastered. Yet some current agricultural practices remain remarkably inefficient, wasting precious resources and polluting both land and sea.
A team of scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory has been working for nearly a decade to control some of the more environmentally harmful side effects of modern farming.
“We’re coming up with ways to use the landscape better so that we can increase the sustainability of everything we grow, including bioenergy and food crops,” said Cristina Negri, director of Argonne’s Environmental Science Division. “Land and water are in limited supply, so we have to use these resources in the smartest and least harmful ways possible.”
Negri’s team is investigating the use of bioenergy buffers — like perennial biomass crops, such as willow and native prairie grasses — in agricultural lands to reduce the impact of soil nutrients on water quality.
Excess nutrients — namely nitrates — in farmed soil can leach into surface water and shallow groundwater, increasing the cost to treat drinking water.
Among the more dramatic impacts is the eutrophication (e.g., excessive richness in nutrients) of surface water, as seen in the Gulf of Mexico, where nitrogen runoff has caused harmful algal blooms that eventually lead to massive fish kills.
Primary target areas for the team’s work are those where the bioenergy crops can intercept nutrients in the subsurface and in underproductive soils, where excess fertilizer is more likely to leach.
Buffer placement is also important from a bioenergy production standpoint. Intercepted nutrients are a fertilizer source for willows and enhance biomass production.
A perennial bioenergy crop provides other ecosystem services, as well: essentially eliminating erosion, improving water and air quality and providing additional wildlife habitat. Willows can also be used in the production of biofuels and bioproducts.
Negri, an agronomist and environmental engineer, conceived of the approach and led the project from the start. John Quinn, hydrogeologist in the Water and Aquatic Resources Department at Argonne, currently leads the team’s on-the-ground work.
The Argonne scientists conducted much of their research on a 16-acre corn and soybean field in Fairbury, Ill., about 90 minutes south of the laboratory. They visited the parcel at least biweekly during the growing season to measure crop productivity, nutrient leaching and greenhouse gas emissions.
Their findings can be scaled to larger watersheds through computer modeling.