A look into 30 years’ worth of data shows that a key agricultural region in China is slowly drying out, according to a research team from Purdue University and China Agricultural University.
The study found that available soil moisture during the growing season in Northern China has decreased by 6% since 1983. Researchers say that optimal soil moisture levels for the region’s farmland ranges from 40% to 80%. Current levels are less than 40% - and the problem is only getting worse.
“The soil moisture declined by 1.5% to 2.5% every decade of the study,” says Purdue agronomy professor Qianlai Zhuang. “While climate change is still a factor, this water depletion appears to be largely driven by human activities. A 10% decline in soil moisture over the course of a century would have major implications for agriculture and the freshwater supply in this heavily populated area.”
About 40% of China’s population lives in the northern part of the country, and it accounts for about 65% of the nation’s farmland.
Zhuang says that while this problem has been well documented, the causes as well as the impacts of intensifying agriculture in Northern China have been understudied.
“This information is critical to improvement of agricultural practices and water resource management,” he says. “The demand for food and water is increasing, but current practices to meet this demand threaten the future security of water resources.”
Specifically, the study showed a consistent correlation between reduced soil moisture and increased fertilizer usage and an increased planting of crops that require more water, such as corn.
“Fertilizer has been overused in China, which accounts for 31.4% of the total global consumption,” says study co-author Yaling Liu. “Although the negative effects of using fertilizer in excess of the needs of the crop is recognized by the scientific community, it is difficult to reverse the farming practices.”
Although increased fertilizer use is not the only factor at play, researchers say it still serves as a “broad diagnostic” regarding the level of intensified agriculture. Other factors that also play a role in drying the land include newer crop varieties that have higher demand and an increase in irrigation practices.
Liu says the study underscores the importance of sustainable agriculture practices. She says the Chinese government is vested in finding solutions, making the study an important step toward sustainable solutions.
“Perhaps crops that require less water could be substituted, water-saving technologies like mulching, reduced tillage, drip irrigation and improved soil-crop system management could be employed more broadly, and advances in agriculture technology could improve the situation,” she says.
The researchers published a paper detailing the study’s results in the July 9 edition of Nature’s Scientific Reports journal.