Win the battle against agricultural non-point source pollution and advance sustainable agricultural development

At present, China's agricultural and rural economic development has entered its best historical period, with grain production achieving "eleven consecutive years of increases," remaining stable above 1200 billion jin for two consecutive years. While tremendous achievements have been made, tremendous costs have also been paid, the string of resource utilization is being pulled tighter and tighter, and the carrying capacity of the ecological environment is getting closer and closer to its limit. Facing the double "tightening band" of resource conditions and the ecological environment, there is an urgent need to transform the mode of agricultural development, strengthen the treatment of agricultural non-point source pollution, effectively advance the protection and treatment of the agricultural ecological environment, and promote sustainable agricultural development.

I. Scientifically grasp the situation of agricultural non-point source pollution and effectively enhance the sense of urgency and responsibility in agricultural non-point source pollution prevention and control work

The First National Pollution Census showed that in 2007, chemical oxygen demand (COD), total nitrogen, and total phosphorus emissions from agricultural sources nationwide reached 13.2 million tons, 2.7 million tons, and 280,000 tons respectively, accounting for 43.7%, 57.2%, and 67.4% of the national total emissions respectively. Among these, livestock and poultry breeding sources accounted for 96% of agricultural source COD, making them the main "contributors" to agricultural non-point source pollution. Livestock and poultry farming, aquaculture, and inputs of agricultural chemicals such as chemical fertilizers, pesticides, and agricultural films are the main sources of pollution. Unlike industrial point source pollution, which enters water bodies directly through centralized discharge outlets, agricultural non-point sources discharge in a dispersed manner, and their pollution process from agricultural production behavior to discharge and ultimately to environmental impact is not a simple direct causal relationship. Research shows that 35% of nitrogen in chemical fertilizers applied to farmland in China is utilized by crops in the current season, with the vast majority of the remainder retained in farmland soil, a small amount flowing into ditches, and ultimately less than 5% entering surface water bodies through runoff. Therefore, although China's total agricultural source pollutant emissions are relatively high, the amount actually entering water bodies remains very limited.

At the current stage, the overall situation of agricultural non-point source pollution is severe, but there are also some particularities that require us to carefully study and assess and implement precise measures.

⟦NL> First, the degree of intensification in the breeding industry is increasing. Due to the relatively low utilization rate of livestock and poultry manure and other waste as resources, pollution emissions show an upward trend. In recent years, China's total livestock and poultry breeding volume has continued to increase, with national hog slaughter exceeding 700 million head in 2013. At the same time, large-scale intensification has developed rapidly, with the proportion of large-scale breeding operations with annual hog slaughter of 500 head or more reaching 40.8%. Meanwhile, the construction of breeding waste treatment facilities has lagged relatively behind, and large amounts of livestock and poultry manure are difficult to treat and utilize in a timely manner, turning livestock and poultry breeding waste from traditional farmyard manure into pollutants. In addition, China's aquaculture scale is also expanding rapidly. In 1978, total aquatic product output was 4.654 million tons, of which artificial breeding accounted for 26.1%. By 2013, total aquatic product output reached 61.72 million tons, with artificial breeding accounting for 73.6%. The large amounts of feed and fish medicine input in aquaculture cause water environment pollution.

Second, chemical fertilizer use for major grain crops is basically reasonable, while excessive application is more prominent for economic crops such as vegetables and melons and fruits. Overall, the growth rate of chemical fertilizer consumption is declining, but the amount of chemical fertilizer input remains relatively large.

In 2013, China's chemical fertilizer use was 59.12 million tons, accounting for 35% of the world's total. Calculated based on 2.03 billion mu of cultivated land, the average chemical fertilizer application per unit area reached 436.8 kg/hectare, still far higher than the world average. It is worth noting that the average nitrogen fertilizer use for major grain crops in China is currently about 212 kg/hectare, already below the environmental safety upper limit (the safety upper limit set by developed countries to prevent water pollution is 225 kg/hectare), but the average nitrogen fertilizer use of 555 kg/hectare for fruit trees and 365 kg/hectare for vegetables is still far above environmental safety requirements, and excessive chemical fertilizer application in orchards and protected vegetable cultivation is still relatively prominent.

Third, pesticide use per unit area is higher than the world average but lower than that of developed countries such as the United States. Overall use tends to be stable, but the utilization rate is relatively low. In recent years, China's pesticide use has stabilized at around 320,000 tons (active ingredients), accounting for 1/7 of the world's total pesticide use, a proportion higher than China's land area as a share of the world's cultivated land area, which is related to China's high multiple cropping index. Overall, China's pesticide use per unit area is higher than the world average but lower than that of developed countries such as the United States, Israel, and Japan. On the other hand, China's current pesticide utilization rate is relatively low, at only 35%. Residual pesticides entering water bodies through precipitation, surface runoff, and soil leaching will lead to deterioration of soil and water environment quality, disrupt ecology, and affect biodiversity.

Fourth, the recovery rate of plastic film is relatively low, and the problem of residual worn agricultural film remains to be solved. China ranks first in the world in both total plastic film use and crop coverage area. In 2013, national agricultural film usage was 2.493 million tons. Due to the large-scale use of ultra-thin plastic film and the lack of residual film recovery and reuse technology and mechanisms, the "white revolution" has gradually evolved into "white pollution," and the problem of plastic film residue pollution in farmland has become increasingly prominent. Plastic film residue is severely harmful, affecting soil structure and reducing cultivated land quality; affecting seedling emergence and causing yield reduction; affecting agricultural machinery operations and causing declines in sowing and fertilization quality; and livestock accidentally ingesting it occurs continuously, harming livestock health.

Fifth, the comprehensive utilization rate of crop straw is relatively low, and the capacity for circular utilization urgently needs improvement. Crop straw is an agricultural resource with abundant uses. According to estimates, in 2013 the total national straw output and its collectible and usable amount were 964 million tons and 819 million tons respectively, with actual utilization of about 622 million tons, and the comprehensive utilization rate was only 76%. With changes in the agricultural energy structure, the proportion of crop straw in domestic energy use is becoming smaller and smaller. The outlets for surplus straw are: first, burning it on the spot, causing air pollution, reducing atmospheric visibility, hindering traffic, and harming human health; second, discarding it in field ditches or piling it into rivers or lakes, where through weathering, rain leaching, and decomposition, organic matter in the straw enters water bodies and causes pollution.

In general, with the continuous improvement of China's agricultural intensification and the rapid development of the breeding industry, the problem of agricultural non-point source pollution caused by excessive use of agricultural inputs such as chemical fertilizers and pesticides and unreasonable disposal of agricultural waste such as livestock and poultry manure, crop straw, and residual farmland film has become increasingly prominent, severely constraining the sustainable development of agriculture and the rural economy. Therefore, strengthening the treatment of agricultural non-point source pollution is a practical need to ensure the safety of agricultural product production areas and achieve China's food security and agricultural product quality and safety, and is an inherent need to improve the agricultural ecological environment, accelerate the transformation of the agricultural development mode, and achieve sustainable agricultural development. We must scientifically grasp the increasingly severe situation of agricultural non-point source pollution, deeply recognize the major significance of strengthening agricultural non-point source pollution treatment, and effectively enhance the sense of urgency and responsibility in our work,

II. Positive progress has been made in agricultural ecological environment protection and treatment work, laying a solid foundation for winning the battle against agricultural non-point source pollution

China's agricultural non-point source pollution is the result of long-term accumulation and has its particularities and complexities. It cannot be completely solved overnight and requires prolonged unremitting efforts. In recent years, agricultural departments at all levels, while safeguarding agricultural development, have continuously increased efforts in agricultural ecological environment protection and treatment work, initially established agricultural non-point source pollution prevention and control teams and expert support teams, and gradually established and improved the policy system, exploring and forming a batch of practical technologies and typical models. All of these have laid a good foundation for winning the battle against agricultural non-point source pollution.

First, system and team building has been continuously strengthened. A four-level agricultural environmental protection management system has been formed, led by two national-level general stations, with 33 provincial, autonomous region, municipality directly under the Central Government, and separately listed city agricultural environmental protection stations as the main body, and 326 prefecture-level stations and 1794 county-level stations as the foundation, providing team and system guarantees for agricultural ecological environment monitoring and prevention and control.

Second, monitoring and early warning capabilities have been continuously improved. A national agricultural non-point source pollution monitoring network has been initially constructed, continuously advancing the normalized and institutionalized operation of agricultural non-point source pollution monitoring; a four-level cultivated land quality monitoring network at the national, provincial, municipal, and county levels has been built, and national-level cultivated land quality monitoring annual reports are issued; an environmental monitoring network system covering China's offshore bays, islands and reefs, tidal flats, nature reserves, aquatic germplasm resource protection areas, and aquaculture waters has been initially formed, with the "China Fishery Ecological Environment Status Bulletin" issued regularly. A state-controlled monitoring network for agricultural product production area pollution has been established, and investigations into heavy metal pollution in production areas have been carried out.

Third, vigorous efforts have been made to promote scientific application of chemical fertilizers and pesticides. Soil testing and formula fertilization technology has been comprehensively popularized, with promotion area reaching 1.4 billion mu; green prevention and control has been deeply implemented, with 150 national-level green prevention and control demonstration zones established, 33 highly toxic pesticides successively phased out, and vigorous promotion of the use of high-efficiency, low-toxicity, low-residue, and biological pesticides; pilot construction for the integrated advancement of specialized unified prevention and control of crop diseases and pests with green prevention and control has been carried out, with 218 demonstration bases established; in early 2015, the "Action Plan for Zero Growth in Chemical Fertilizer and Pesticide Use by 2020" was issued, launching the action for zero growth in chemical fertilizer and pesticide use.