December 17, 2014
from
UNL
Website
Ken Cassmann, Ph.D. -
Professor
Agronomy and Horticulture
402-472-1555 - kcassman1@unl.edu
Dan Moser - IANR News Service
402-472-3030 - dmoser3@unl.edu |
LINCOLN, Neb.
About 30 percent of the major global cereal
crops,
...may have reached their maximum possible
yields in farmers' fields, according to University of Nebraska-Lincoln
research published this week in Nature Communications (see
Distinguishing Between Yield Advances and Yield
Plateaus in Historical Crop Production Trends).
These findings raise concerns about efforts to
increase food production to meet growing global populations.
Yields of these crops have recently decreased or plateaued. Future
projections that would ensure global food security are typically based on a
constant increase in yield, a trend that this research now suggests may not
be possible.
Estimates of future global food production and its ability to meet the
dietary needs of a population expected to grow from 7 billion to 9 billion
by 2050 have been based largely on projections of historical trends. Past
trends have, however, been dominated by the rapid adoption of new
technologies - some of which were
one-time innovations - which allowed
for an increase in crop production.
As a result, projections of future yields have been optimistic - perhaps
too much so, indicates the findings of UNL scientists
Kenneth Cassman and
Patricio Grassini, of the agronomy and
horticulture department, and Kent Eskridge of the statistics
department.
They studied past yield trends in countries with greatest cereal production
and provide evidence against a projected scenario of continued linear crop
yield increase.
Their data suggest that the rate of yield gain
has recently decreased or stopped for one or more of the major cereals in
many of the most intensively cropped areas of the world, including eastern
Asia, Europe and the United States.
The Institute of Agriculture and Natural Resources scientists
calculate that this decrease or stagnation in yield gain affects 33 percent
of major rice-producing countries and 27 percent of major wheat-producing
countries.
In China, for example, the increase in crop yields in wheat has remained
constant, and rate of corn yield increase has decreased by 64 percent for
the period 2010-2011 relative to the years 2002-2003 despite a large
increase in investment in agricultural research and development, education
and infrastructure for both crops.
This suggests that return on these investments
is steadily declining in terms of impact on raising crop yields.
The authors report (Distinguishing
Between Yield Advances and Yield Plateaus in Historical Crop Production
Trends) that 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.