(July 10, 2015) An
important agricultural region in China is drying out, and increased farming may
be more to blame than rising temperatures and less rain, according to a study
spanning 30 years of data.
A research team led by Purdue University and China
Agricultural University analyzed soil moisture during the growing season in
Northern China and found that it has decreased by 6 percent since 1983.
The optimal soil-moisture level for farmland is typically 40
percent to 85 percent of the water holding capacity, and the region's soil is
now less than 40 percent and getting drier. If this trend continues, the soil
may not be able to support crops by as early as 2090, said study leader Qianlai
Zhuang, Purdue's William F. and Patty J. Miller Professor of Earth, Atmospheric
and Planetary Sciences and Agronomy.
"The soil moisture declined by 1.5 to 2.5 percent every
decade of the study and, while climate change is still a factor, this water
depletion appears to be largely driven by human activities," Zhuang said.
"A 10 percent decline in soil moisture over the course of a century would
have major implications for agriculture and the fresh water supply in this
heavily populated area."
Forty percent of the nation's population resides in Northern
China, according to the country's population census office. The region also
accounts for 65 percent of the nation's cropland, Zhuang said.
"The drying of soil in Northern China has been well
documented, but its causes and the impacts of agricultural intensification in
general have been understudied," he said. "This information is
critical to improvement of agricultural practices and water resource
management. The demand for food and water is increasing, but current practices
to meet this demand threaten the future security of water resources.
Unfortunately, with the growing world population, more and more regions could
face the same circumstances of agricultural intensification for food
security."