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Agricultrual Non-point Pollution Control and Farmland Nutrient Management in China


Abstract: This report is a proposal made by the Chinese Academy of Sciences to the China Council for International Cooperation on Environment and Development (CCICED) to conduct a study on agricultural non-point pollution control in China. It analyzed the problems of food and environmental safety resulted from non-point pollution in China, identified research foci and listed related previous studies and the necessity and feasibility for international cooperation. It concluded with the recommendation to establish a new task force to address the issue in the third phase of CCICED.


China is known as a large country in population and also in agriculture. For a population of over 1.2 billion, farmlands in China is quite limited, with a total area of about 140 million ha. To meet our large demands for food and other agricultural products, the key strategy taken in China has been increasing the productivity of the existing, high-yield crop varieties, and increasing the use of chemical fertilizers. Due to its success in past 50 years, China has historically overcome its food shortage. Protecting rural environment becomes an important goal to sustain agriculture and to develop rural economy in China. This requires information on the impacts of agriculture on environments (mainly lands and water), and knowledge and technologies in controlling and manipulating non-point pollution, particularly in nutrients released from farmlands into the environment.

2.Changes in fertilizer application pattern in China

In the past 50 years, Chinese agriculture developed from completely a traditional era into nowadays a so-called 'chemical era'. This development, like already happened in many other countries, was based on changes in agricultural inputs, as from self-supplied manure to chemical products (mainly fertilizers). It would consequently lead to fundamental changes in the sources, forms, and more importantly, quantities of nutrients (NPK) released from farmlands to the environment.

There were different stages in changes in farmland nutrient inputs in China. Before 1950, as little chemical fertilizer had been used in Chinese agriculture, farmland nutrient inputs in China were mainly from farmyard manure, muck, crop straws, plant ashes, sewage and so on. The industrial production of chemical fertilizers was started in China in 1950s, but to the end of 1960s only a limited amount of N fertilizers was provided. During this period, farmland nutrient inputs remained as traditional forms. By early 1980s, chemically produced N fertilizers increased up to about 50% of total N input into farmlands in China, and chemical P and K fertilizers also started to use. This led to a remarkable change in the structure of farmland nutrient inputs in China. By the middle of 1980s, major sources of farmland nutrient inputs in China. By the middle of 1980s, major sources of farmland nutrient inputs in developed areas in China were chemical fertilizers, whereas the proportions from traditional fertilizers decreased rapidly. From 1990s, such situation has spread over major agricultural areas in China.

Historical data of chemical fertilizers applied in China provides further information to reflect changes in farmland nutrient inputs. Before 1965, the annual amount of total chemical fertilizers applied in China was below 1.9 m tons. It is increased by about 3 folds each 10-year by 1985, and then doubled by 1995, in 2000, the amount of fertilizer reached 42 m tons, a record high in history. Increase in the application of chemical fertilizers has definitively played a dominant role to increase Chinese agricultural productivity. However, the efficiency of chemical fertilizers, as either their crop productivity per unit or the proportion of their nutrients utilized by crops, decreased as increase in the amount applied. For example, the present crop utilizing deficiencies of N, P, K, from chemical fertilizers are 30-45%, 10-25%, and 40-50%. Therefore, chemical fertilizers, as giving the large quantity applied at present, could considerably be an important source of nutrients as surface pollutants to the environment.

3. Environmental risks of excessive use of chemicals in agriculture

With traditional styles of nutrient inputs, there was little evidence on environmental risks in the long history of traditional agriculture in China. Since 1980s, chemical fertilizers have widely been used in China, and meanwhile, rural industries have rapidly developed in eastern coastal regions in China. It is in these regions that the risks of non-point pollution become obvious, mainly indicated as eutrophication problem of lakes and reservoirs.

Nutrients, dominated by nitrate-N and phosphate-P, released from farmlands, pesticides, and polluted water and sewage slurry emitted from local cities and rural areas are the major sources of non-point pollutants. By 1998, the annual average of fertilizer-N applied farmlands over China was about 225 kg/ha, which was equal to the internationally recognized critical level. There were 17 provinces higher than the critical level, amongst 4 of them over 400 kg/ha. It was estimated that annually some 10 m tons of fertilizer-N has released to the environment, with 1.7 m tons run into inland river systems through surface runoff and soil leaching. Over 50% of fresh-water lakes in China were at the risk of eutrophication. Of them, Dianchi Lake in Yunnan province, Taihu Lake in Jiangsu province, and Chaohu Lake in Anhui province were grossly polluted by eutrophication. The eutrophication of river water could be cause of red tides in offshore seas. In many regions of China, the content of nitrate-N in underground water has reached a critical level (e.g.50-300 mg/l).

4. Suggestion for CCICED studies in the near future

As the bases of human health and ecological safety, environmental quality has become one of the top priorities, as important as economic development. To control and manipulate non-point pollution is a very important target.

Main areas considered in the suggestion are as follows:

(1) The sources of non-point pollutants and their flux to environment

Researches in this area include the amounts of non-point pollutants from different sources and their proportional contributions in the total released to the environment. At present, there are 3 principal sources: nutrients released from farmlands, sewage slurry from rural regions (local towns and villages), and accurately monitor the processes and flux of nutrient transformation and transfer of different sources (farmland, towns and villages, and aquaculture and animal farms) to surrounding environment.

(2) Environmental impacts of non-point pollution

Key issues in this area are the effects of non-point pollution on the quality of regional water (surface water, underground water and lakes), soils, and agricultural products, particularly foods.

Researches on water quality will be focused at the fluxes of nutrients from farmlands, and human waste in rural residential areas, aquaculture and animal farms, the proportional contribution of the discharges on the environment, lake eutrophication and technology to control such emissions.

Researches on soil quality will mainly be on the transports of nutrients in soil and their release to the environment; the risks of over use of N and P fertilizers; the activity of heavy metals in soils and the contamination in food and other agricultural products.

(3) Policies in controlling and manipulating non-point pollution

Researches in this area will focus on providing scientific supports to formulate regulations for proper fertilizer applications and field nutrient management, the treatments of human wastes, and the management of discharges from aquaculture and animal farms etc. The household behavior for over use of chemicals and related policies, market system and extension service will also be important issues to address.

5. On-going research programs in Chinese Academy of Sciences (CAS)

There have been preliminary studies on non-point pollution conducted by the institutes of the Chinese Academy of Sciences, such as the release of nutrients from farmland and the impacts of typically nutrient-polluted lakes in China. In recent years, the controlling and manipulating technologies of non-point pollution and water eutrophication have been underlined as one of the important areas in ecological and environmental studies. Under the National Knowledge Innovation Program launched by CAS in 1999, several projects have already been being implemented in this area. For instance, "The transformation, transport and optimum management of NPK in main farmland eco-systems in China," "The pre-warning studies of aquatic environment in the Taihu Lake Basin," "The impact of soil pollution on the quality of soil and agricultural products."

It is expected that researches under these projects can improve our understanding on non-point pollution and its impact on agriculture and the environment. Knowledge generated from these projects will provide a solid base for further researches into this area, and also the goal to sustain the development of agriculture and rural environment in China.

6. Call for international collaboration 

Non-point pollution has been recognized as a worldwide problem, not only to the Chinese government and scientists, but to the international communities as well. Through the new CCICED initiative of establishing joint task forces, we hope to get the right expertise, knowledge and technology, and financial support to tackle the problem of non-point pollution. It is urgent and imperative. For the time being, the concerned countries and international organizations include the USA, Canada, EU member states, Japan, Australia, IAEA, FAO, ACIAR, JSPS and etc. They are the potential partners, and some of them have shown interest.

Through all the efforts mentioned, we believe the CCICED could approve our proposal to set up a task force on non-point pollution control, which will undoubtedly meet the challenge in front.

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