Chinese rivers contain alarming quantities of nitrogen and phosphate thanks to Chinese agricultural policy, writes PhD candidate Maryna Strokal of Environmental Systems Analysis and her Chinese and Wageningen colleagues in the journal Environmental Research Letters.
Changes to Chinese agriculture in the past few decades have led to a livestock sector which is disconnected from crop production, observe the researchers. This means that manure produced on livestock farms does not get used to improve the fertility of arable farmland. In 2000 between 30 and 70 percent of all animal manure was dumped in rivers, states Strokal. By comparison, this figure was 5 percent in 1970. Meanwhile the number of livestock animals in China has doubled in those 30 years.
The result of these agricultural developments is that the concentration of nitrogen and phosphate in Chinese rivers has gone up by a factor of between 2 and 45 in the space of 30 years. Although there is growing concern about this environmental pollution in China, the dumping of manure straight into the rivers could increase in the coming years, warns Strokal. She advises the Chinese government to take action promptly to recycle more manure from livestock in horticulture and agriculture.