Challenging current approaches to estimating crop yield potential
Accurate estimates of crop yield potential and gaps are key in planning how to meet growing food demand globally. Nebraska agronomists significantly contributed to an international study that demonstrates long-standing statistical methods are insufficient.
“We are in a race to feed the world and to try to feed the population with the available agricultural land that we have,” said Patricio Grassini, Sunkist Distinguished Professor of Agronomy and an author of the Nature Food paper outlining the team’s findings.
Predicting both yield potential, as determined by weather and soil properties, and yield gaps, the difference between yield potential and current farm yields, helps guide investments in agricultural research and development, both from public and private sources.
The most widely used methods to compile those estimates tend to rely too heavily on best-case scenarios – the most productive counties with the most fertile soils in a year with the most favorable weather, Grassini said. They also extrapolate a single yield potential across large regions with a wide diversity of climates and soils that likely would produce a similarly wide range in yield potential.
In some instances, those methods can overestimate yield potential; in others, they might underestimate it.
The team’s study compared estimates of yield potential and yield gaps of major U.S. rainfed crops – corn, soybeans and wheat – derived from four statistical models against those derived from a “bottom-up” spatial scaling approach based on robust crop modeling and local weather and soil data, such as the Global Yield Gap and Water Productivity Atlas developed at Nebraska.
The team discovered that a bottom-up approach that incorporates local weather and soil data and accounts for regional variations, is superior. This approach could better quantify yield gaps, which may help scientists, agronomists and policy makers identify regions with the greatest potential to increase crop production.
This is a call to set the record straight because if we are going to use this information to inform policy and our investments, we better make sure that the information is sound and has been validated.
Patricio Grassini
Grassini said he expects the study to challenge prevailing attitudes.
“This is a call to set the record straight because if we are going to use this information to inform policy and our investments, we better make sure that the information is sound and has been validated,” said Grassini.
The international team includes scientists from Kansas State University, Iowa State University and the French Agricultural Research Centre for International Development.