About 30% of global food production of major cereal crops may have reached top possible yields in farmers’ fields, says a new study carried out at the University of Nebraska-Lincoln and published in Nature Communications.
The researchers found that estimates regarding future global food production may have been overly-optimistic.
Yields of rice, wheat and corn have either dropped or plateaued. Forecasts regarding global food production usually factor in increasing yields, a trend that the study authors say may not be achievable.
The world’s population is expected to grow from 7 billion today to 9 billion by 2050. Estimates of future global food production are mainly based on projections of historical trends, and forecast increasing yields that will meet growing demand.
Historical tends have, however, been mainly driven by the rapid adoption of new technologies, some of which were one-off innovations, which brought about important increases in crop production.
Global food production forecasts overly-optimistic
Consequently, forecasts of future yields have been overly-optimistic, say Kenneth Cassman and Patricio Grassini, who work at the university’s agronomy and horticulture department, and Kent M. Eskridge from the statistics department.
The researchers collected and analyzed data on historical yield trends in the major cereal-producing nations, and found evidence to demonstrate that future projections of crop yield increases are unrealistic.
According to their data, crop yield growth in much of Asia, the United States and Europe, areas with highly-intensive farming, has either stopped or decreased.
Thirty-three percent of the world’s major rice-producing nations and 27% of major wheat-producing countries are affected by decreasing yield growth or stagnation, the authors found.
Cassman and Grassini report that in China the increase in wheat crop yields has remained constant, while growth in corn yields fell by 64% during the 2010-2011 period compared to 2002-2003, in spite of major increases in investment in agricultural R&D, education and infrastructure for both crops.
As far as crop yields are concerned, return on these investments is progressively falling.
Overly-optimistic projections of grain production have often been backed up by unverifiable ‘record’ crop yields. The authors quote a well-known goal for average US maize yield by 2030 which would require growth of 3.6% annually (compounded), a rate four times larger than the growth in US maize yield from 1965 to 2011.
Cassmann wrote:
“Sustaining further yield gain likely would require fine tuning of many different factors in the production of crops.”
“But this is often difficult to achieve in farmers’ fields and the associated marginal costs, labour requirements, risks and environmental impacts may outweigh the benefits.”
In an Abstract in the journal, the researchers concluded:
“Estimating future food production capacity would benefit from an analysis of past crop yield trends based on a robust statistical analysis framework that evaluates historical yield trajectories and plateaus.”
