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 In a new study, an interdisciplinary team from the University of
Illinois linked crop insurance, climate, soil and corn yield
data from 1981 through 2016.
The study found that during some years, excessive rainfall
reduced U.S. corn yield by as much as 34% relative to the
expected yield. Data suggest that drought and excessive heat
caused a yield loss of up to 37% during some years. The findings
are published in the journal Global Change Biology.
“We linked county-level U.S. Department of Agriculture insurance
data for corn loss with historical weather data, letting us
quantify the impact of excessive rainfall on yield loss at a
continental scale,” said Kaiyu Guan, assistant professor in the
Department of Natural Resources and Environmental Sciences at U
of I, Blue Waters professor at the National Center for
Supercomputing Applications, and the study’s principal
investigator. “This was done using crop insurance indemnity data
paired with rigorous statistical analysis – not modeled
simulations – which let the numbers speak for themselves.”
The study found that the impact of excessive rainfall varies
regionally.
“Heavy rainfall can decrease corn yield more in cooler areas and
the effect is exacerbated even further in areas that have poor
drainage,” said Yan Li, a former U. of I. postdoctoral
researcher and lead author of the study.
Excessive rainfall can affect crop productivity in various ways,
including direct physical damage, delayed planting and
harvesting, restricted root growth, oxygen deficiency and
nutrient loss, the researchers said.
“It is challenging to simulate the effects of
excessive rainfall because of the vast amount of seemingly minor
details,” Yan said. “It is difficult to create a model based on
the processes that occur after heavy rainfall – poor drainage
due to small surface features, water table depth and various
soil properties can lead to ponding of water in a crop field.
Even though the ponding may take place over a small area, it
could have a large effect on crop damage.”
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“This study shows that we have a lot of work to do to
improve our models,” said Evan DeLucia, director of the Institute
for Sustainability, Energy and Environment, professor in the
Department of Plant Biology at U of I, and study co-author. “While
drought and heat stress have been well dealt with in the existing
models, excessive rainfall impacts on crop system are much less
mature.”
Many climate change models predict that the U.S. Corn Belt region
will continue to experience more intense rainfall events in the
spring. Because of this, the researchers feel that it is urgent for
the government and farmers to design better risk management plans to
deal with the predicted climate scenarios.
“As rainfall becomes more extreme, crop insurance needs to evolve to
better meet planting challenges faced by farmers,” said Gary
Schnitkey, professor in the Department of Agricultural and Consumer
Economics at U of I and study co-author.
The paper, “Excessive rainfall leads to maize yield loss of a
comparable magnitude to extreme drought in the United States” is
available online and from the U. of I. News Bureau. DOI:
10.1111/gcb.14628. Kaiyu Guan and Gary Schnitkey are faculty in the
College of Agricultural, Consumer and Environmental Sciences at the
University of Illinois. The USDA, National Institute of Food and
Agriculture, and the U.S. Department of Energy supported this study.
[Source: Kaiyu Guan,
News writer: Lois Yoksoulian]
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