Irrigated corn achieves high yields

Research by UNL agronomy professors Ken Cassmann and Patricio Grassini found that, contrary to popular belief, high yield, irrigated corn production can be highly efficient and more than offset the cost of inputs. Contrary to conventional wisdom, irrigated corn in Nebraska is highly efficient in the use of energy, water and fertilizer, say University of Nebraska-Lincoln scientists whose research found that increased yields more than offset the energy cost of these inputs.

This research has important ramifications for agriculture's efforts to meet increasing global needs for food, feed, fuel and fiber on existing farmland, said Ken Cassman, UNL agronomist who holds the university's inaugural Robert B. Daugherty Professorship. Cassman and Patricio Grassini, a UNL research professor in agronomy and horticulture, co-authored a paper about their research that appears in this week's Proceedings of the National Academy of Sciences.

"If the goal is simply to reduce greenhouse gases or to have the highest possible energy efficiency, you'd do that producing crops without any inputs at all, or by getting rid of agriculture entirely. Of course that's not a tenable position," Cassman said. "The challenge therefore is how to produce enough food in a way that also protects the environment, conserves natural resources and minimizes the greenhouse gas emissions from agriculture."

The UNL research shows that modern, irrigated, high-input agriculture, though it uses more fossil fuels and generates more climate-change-causing greenhouse gases than rainfed systems, also produces much higher crop yields. The widely held perception of irrigated agriculture as energy wasteful fails to take into account crop-management changes in recent decades that have increased yields without requiring more fertilizer or irrigation, Cassman said. Those changes have steadily boosted the energy efficiency of irrigated corn grown in the western Corn Belt and High Plains, including Colorado, South Dakota, North Dakota, Nebraska, Kansas, Oklahoma and parts of Texas, which accounts for about 15 percent of U.S. corn production.

"In fact, we found that irrigated corn had substantially larger net energy yield and less greenhouse gas emissions per unit of grain produced than corn from rainfed systems with much smaller input levels and lower yields," Grassini said.

The findings are based on several years' field data collected from a large number of commercial production fields in Nebraska. This "rigorous on-farm assessment" is a first, Grassini explained. Previous research used secondary data gathered and extrapolated by the U.S. Department of Agriculture through producer surveys.