Overuse of fertilizers and pesticides in China linked to farm size
A new study finds chemicals are often used inefficiently on small farms in China. Land and migration policies may help explain why the country uses 30 percent of the world's fertilizers and pesticides on 9 percent of global cropland.
The size of farms in China is a key contributor to the overuse of agricultural chemicals, and as a result they may be too small to be environmentally sustainable, a new study has found.
The research – conducted by a team from the Universities of Melbourne, Zhejiang, Fudan, Wuhan and Stanford – is published in the Proceedings of the National Academy of Sciences of the United States of America.
The study found agricultural chemicals are often used inefficiently on small farms, leading to financial losses and serious local, regional and global pollution ranging from eutrophication (an excess of nutrients in bodies of water, often caused by run-off from the land) to particle pollution in the air and global warming.
According to University of Melbourne and Zhejiang researcher Baojing Gu, China is the world’s largest consumer of agricultural chemicals, using more than 30 percent of global fertilizers and pesticides on only 9 per cent of the world’s crop land. "Our study sought to understand the reasons for overuse of agricultural chemicals," he said, "because addressing this is critical to the sustainable development of Chinese agriculture."
A small farm in rural Hainan Province, China. Previous research has recognized the importance of small farm sizes and barriers to aggregation in China, says Stanford biologist and study co-author Peter Vitousek. But he was surprised to see "what a dominant feature that is, and how it is maintained by national policies designed for other purposes." (Photo credit: Wikimedia Commons)
The study used a nationally representative rural household survey from China and found that small farm size strongly affects the use and intensity of agricultural chemicals across farms in China. A 1 percent increase in farm size was found to be associated with a 0.3 percent and 0.5 percent decrease in fertilizer and pesticide use per hectare, respectively. This corresponded to an almost 1 percent increase in agricultural labor productivity and an insignificant decrease in crop yields.
“In recent years, the Chinese government has made efforts to reduce excessive use of agricultural chemicals, but the effects have unfortunately been limited," said University of Melbourne Professor Deli Chen. "While economic growth has been associated with increasing farm size in other countries, in China this relationship has been distorted by land and migration policies, leading to the persistence of small farm size."
The authors suggest that removing these distortions would decrease agricultural chemical use by 30 to 50 percent and the environment impact of those chemicals by 50 percent, while doubling the total income of all farmers including those who move to urban areas.
Biologist and study co-author Peter Vitousek, who directs the Emmett Interdisciplinary Program in Environment and Resources in Stanford University's School of Earth, Energy & Environmental Sciences, said previous research has recognized the importance of small farm sizes and barriers to aggregation. "But I was surprised that the current paper showed what a dominant feature that is, and how it is maintained by national policies designed for other purposes."
“Small farm size has proliferated in China, largely due to the misallocation of cropland and labor caused by the barriers to the movement of labour and the limits on transfer of cropland use rights,” Gu said. This contributes to the overuse of agricultural chemicals in a number of ways. “Many technological innovations and modern management practices that reduce the use of agricultural chemicals are less effective on small farms due to the high costs of adoption," he said. "People with larger farms typically have better farming knowledge and management skills and so use agricultural chemicals more efficiently than farmers who are operating on a smaller scale.”
The study shows average farm size in China has changed very slowly despite the country’s strong economic growth and urbanization. From the 1980s to 2000s, the country’s average farm size decreased and has increased slowly since the 2000s. This pattern differs substantially from other developed countries.
It also shows 98 percent of households that run farms own a farm measuring less than two hectares in China - a much higher proportion than in other world regions. But the researchers see far-reaching implications for other countries. "While agriculture in less-developed countries, especially in some sub-Saharan African countries, is currently suffering from a deficit in agricultural chemicals, their availability will increase with economic growth,” Chen said. “If nothing is done to address the misallocation of land, labor and capital in agriculture in these countries, they will face the same problems and implications for health and the environment that Chinese agriculture has experienced for the past few decades.”
Peter Vitousek is also the Clifford G. Morrison Professor in Population and Resource Studies, a Senior Fellow at the Woods Institute for the Environment, and Professor, by courtesy, of Earth System Science.
University of Melbourne
School of Earth, Energy & Environmental Sciences