Farmers in China keep increasing the use of chemical fertilizer in an effort to improve yield, while experts warn their overuse is making formerly arable land unusable, degrading the quality of China’s fruit and vegetables, killing lakes and streams, and introducing pollutants into the air.
“If farmers overuse chemical fertilizers for a long period, the fertilizer residues will affect water quality. When the nitrogenous fertilizer is washed away or carried into the air, it will influence air quality,” Xu Mingang, vice director of Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (CAAS), pointed out in an interview with the NTD TV.
Chemical fertilizer use in China has increased by 225 percent since 1980, according to a survey by the Soil and Fertilizer Institute of the Chinese Academy of Agricultural Sciences (CAAS). The yield increased 40 percent during this period.
Nitrogen fertilizer usage is now 191 kg per hectare (170 lb/acre) in China—151, 159, and 329 percent, respectively, of the usage in France, Germany, and the United States. The grain yield in China, however, remains 10-30 percent lower than in those countries.
“The production and consumption of the fertilizer in China are both more than one third of the world. In recent years, in order to increase the grain yield, the use of fertilizer and pesticides has increased, resulting in problems like land desertification, declination of organic matter in lands, and so on,” the general secretary of the Jilin Grain Economic Association, Liu Xiaoran, said, as reported by the Economic Information Daily.
Economic Information Daily reported on Aug. 15 that in Jilin Province, which is China’s largest grain production province, some farmers use the fertilizer for the entire season, in the planting season itself.
The yearly grain yield of Jilin has increased from 10 billion kg to 25 billion kg in the past 30 years. The annual report of the Bureau of Statistics of Jilin Province shows that the use of fertilizer in Jilin, in 1984, was about half a million tons. In 2010, it was 5 million tons
“We know the soil lacks nutrients, so we have to use fertilizers. But we need to use it reasonably. Excess fertilizer will get into the air and water. It will cause pollution,” Ju Xiaotang, a professor at the College of Resources and Environmental Sciences at China Agricultural University, said in an interview with NTD.
“Unreasonable fertilization on one hand increases pests, so more pesticides are needed. On the other hand, lodging phenomenon becomes particularly serious, which reduces production.” Ju said.
“You can compare the vegetables and fruits in foreign markets. Fruits and vegetables in China are of lower quality. It is caused by the overuse of fertilizers.”
“We generally ask [farmers] to use organic manure and leaf stems. If they are not enough, farmers can make it up with [artificial] fertilizer. The combination of these three can increase soil nitrogen and microbial activities. If we only use nitrogenous fertilizer or blend them unreasonably, the nutrients in the soil will be uneven and the soil quality will deteriorate,” Ju said.
Excess nitrogen and phosphorus run into the waters, resulting in eutrophication, an increase of nutrients in the water, Ju points out. Eutrophication in the water bodies results in an excessive growth of algae. As the algae die out and decompose, water is depleted of oxygen, which causes the death of other organisms, such as fish. Ammonia discharges cause air pollution; the nitrous oxide released is a major greenhouse gas, with 298 times more global warming potential than carbon dioxide.
In a report published in the Journal of Ecology and Rural Environment in 2006, researchers from Capital Normal University (CNU) found that the contribution of over-nutrition and organic matter is accountable for 35 to 97 percent of the pollution in five major lakes in China. The CNU report attributes the pollution to three major causes, including fertilizer overuse.Statistics of China’s Ministry of Agriculture say the arable lands rendered unusable are more than 40 percent of the total arable landmass in China, as a result of soil erosion, depletion, alkalinity, and acidification. The polluted cultivated lands are 10 million hectares (24.7 million acres). Arable lands of poor quality with low yield are 67 percent of the cultivated lands. The survey on 10 provinces shows the soil organic matter at present has reduced 35 percent, compared to that in the early 1990s.
Now the annual use of fertilizer in China is more than 54 million tons—including nitrogenous, phosphate, and potash fertilizers. 33 million tons of nitrogenous fertilizer is used.