Do a good job in the Prevention and Control of non-point Source pollution and promote the Sustainable Development of Agriculture

At present, the development of China's agricultural and rural economy has entered the best historical period, and grain production has achieved "11 consecutive increases" and has been stable at more than 1.2 trillion jin for two consecutive years. While making great achievements, it has also paid a huge price. The strings of resource utilization are getting tighter and tighter, and the carrying capacity of the ecological environment is getting closer and closer to the limit. In the face of the double "curse" of resource conditions and ecological environment, there is an urgent need to change the mode of agricultural development, strengthen the control of agricultural non-point source pollution, effectively promote the protection and treatment of agricultural ecological environment, and promote the sustainable development of agriculture.

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

The first national pollution survey showed that in 2007, chemical oxygen demand (COD), total nitrogen and total phosphorus emissions from agricultural sources reached 13.2 million tons, 2.7 million tons and 280000 tons respectively, accounting for 43.7%, 57.2% and 67.4% of the country's total emissions, respectively. Among them, livestock and poultry breeding sources account for 96% of agricultural COD, which is the main "contributor" to agricultural non-point source pollution. Inputs of agrochemicals such as livestock and poultry, aquaculture, chemical fertilizers, pesticides and agricultural films are the main sources of pollution. Different from the industrial point source pollution which directly enters the water body through the centralized discharge outlet, the agricultural non-point source is dispersed discharge, and its pollution process from agricultural production behavior to discharge, and finally to the impact of the environment is not a simple direct causal relationship. The study shows that 35% of the nitrogen in farmland chemical fertilizer in China is used by crops in the current season, and most of the rest is retained in the farmland soil, a small amount flows into the ditch, and finally less than 5% enters the surface water body through runoff. Therefore, although the total discharge of pollutants from agricultural sources in China is relatively high, the amount that really enters the water body is still very limited.

At present, the situation of agricultural non-point source pollution is generally grim, but there are also some particularities, which need us to study and judge carefully and make accurate policies.

First, the intensive degree of aquaculture is getting higher and higher, due to the low utilization rate of livestock and poultry manure and other wastes, pollution emissions are on the rise. The total amount of livestock and poultry breeding in China has been increasing in recent years, with more than 700 million pigs in the country in 2013. At the same time, with the rapid development of scale and intensification, the proportion of scale farming with more than 500 pigs per year has reached 40.8%. At the same time, the construction of breeding waste treatment facilities lags behind, and a large number of livestock and poultry manure is difficult to be treated and utilized in time, which makes livestock and poultry waste become a pollutant from traditional farm manure. In addition, the scale of aquaculture in China is also expanding rapidly. In 1978, the total amount of aquatic products was 4.654 million tons, of which artificial aquaculture accounted for 26.1%. In 2013, the total amount of aquatic products reached 61.72 million tons, and artificial aquaculture accounted for 73.6%. A large number of baits and fish drugs in aquaculture cause water pollution.

Second, the amount of chemical fertilizer used in major food crops is basically reasonable, and the phenomenon of over-application of cash crops such as vegetables, melons and fruits is more prominent. on the whole, the growth rate of chemical fertilizer consumption is declining, but the amount of chemical fertilizer input is still on the high side.

In 2013, the amount of chemical fertilizer used in China was 59.12 million tons, accounting for 35% of the world's total. Based on 2.03 billion mu of arable land, the average amount of chemical fertilizer used per unit area reached 436.8 kg / ha, which is much higher than the world average. It is worth pointing out that at present, the average use of nitrogen fertilizer for major food crops in China is about 212 kg / ha, which is lower than the upper limit of environmental safety (the upper limit of safety set by developed countries to prevent water pollution is 225 kg / ha). However, the average amount of nitrogen fertilizer used for fruit trees 555 kg / ha and vegetables 365 kg / ha is much higher than the environmental safety requirements, and the phenomenon of over-application of chemical fertilizer in orchards and protected vegetables is still more prominent.

Third, the amount of pesticide used per unit area is higher than the world average, but lower than that of the United States and other developed countries. The overall usage tends to be stable, but the utilization rate is low. In recent years, the use of pesticides in China has stabilized at about 320000 tons (active ingredients), accounting for 1 / 7 of the total amount of pesticides in the world, which is higher than the proportion of China's land area to the world's cultivated land area, which is related to the high land multiple cropping index in China. Overall, the amount of pesticide used per unit area in China is higher than the world average, but lower than that in the United States, Israel, Japan and other developed countries. On the other hand, at present, the utilization rate of pesticides in China is low, only 35%. Pesticide residues enter the water body through precipitation, surface runoff and soil infiltration, which will lead to the deterioration of soil and water environment quality, destroy ecology and affect biodiversity.

Fourth, the recovery rate of plastic film is low, and the residual problem of dilapidated agricultural film remains to be solved. The total amount of plastic film use and crop coverage area in China rank first in the world. In 2013, the national consumption of agricultural film was 2.493 million tons. Due to the extensive use of ultra-thin plastic film and the lack of technology and mechanism for the recovery and reuse of residual film, the "white revolution" gradually evolved into "white pollution", and the problem of residual pollution of farmland plastic film has become increasingly prominent. Plastic film residue is seriously harmful, affecting the soil structure, reducing the quality of cultivated land; affecting seedling emergence, resulting in a reduction in yield; affecting the operation of agricultural machinery, resulting in a decline in the quality of sowing and fertilization; livestock feeding continues to occur, endangering the health of livestock.

Fifth, the comprehensive utilization rate of crop straw is low, and the recycling capacity needs to be improved. Crop straw is a rich agricultural resource. It is estimated that the total output of straw and its collectable utilization in 2013 are 964 million tons and 819 million tons respectively, the actual utilization is about 622 million tons, and the comprehensive utilization rate is only 76%. With the change of agricultural energy structure, the proportion of crop straw in domestic energy is becoming less and less, the way out of excess straw is burning on the spot, causing air pollution, reducing atmospheric visibility, hindering traffic and endangering human health; second, abandoned fields and ditches or piled into river ditches or lakes, after weathering, rain and decay, the organic matter in the straw enters the water body to cause pollution.

Generally speaking, with the continuous improvement of agricultural intensification and the rapid development of aquaculture in China, 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 wastes such as livestock and poultry manure, crop straw and farmland residual film has become increasingly prominent, which seriously restricts the sustainable development of agriculture and rural economy. Therefore, strengthening the control of agricultural non-point source pollution is the realistic need to ensure the safety of the producing areas of agricultural products and to realize the food security and the quality safety of agricultural products in our country. it is the inherent need to improve the agricultural ecological environment, speed up the transformation of agricultural development mode and realize the sustainable development of agriculture. We must scientifically grasp the increasingly serious situation of agricultural non-point source pollution, deeply realize the great significance of strengthening the control of agricultural non-point source pollution, and earnestly enhance the sense of urgency and responsibility of the work.

II. Positive progress has been made in the protection and control of the agricultural ecological environment, laying a solid foundation for the prevention and control of agricultural non-point source pollution.

Agricultural non-point source pollution in China is caused by long-term accumulation and has its particularity and complexity, which can not be completely solved overnight and requires unremitting efforts for a long time. In recent years, while ensuring agricultural development, agricultural departments at all levels have continuously stepped up the protection and control of the agricultural ecological environment, initially established working teams and expert support teams for the prevention and control of agricultural non-point source pollution, and gradually established and improved the policy system, exploring and forming a number of practical technologies and typical models, all of which have laid a good foundation for the prevention and control of agricultural non-point source pollution.

First, the building of the system team has been continuously strengthened. A four-level agricultural environmental protection management system has been formed, which is led by two national terminals, agricultural environmental protection stations in 33 provinces, autonomous regions, municipalities directly under the Central Government and cities separately listed on the State plan, and based on 326 prefecture-level stations and 1794 county-level stations. it provides a team system guarantee for the monitoring, prevention and control of agricultural ecological environment.

Second, the ability of monitoring and early warning has been continuously improved. We have initially constructed a national agricultural non-point source pollution monitoring network, continuously promoted the regular and institutionalized operation of agricultural non-point source pollution monitoring, established a four-level cultivated land quality monitoring network at the national, provincial, municipal and county levels, and issued an annual report on national cultivated land quality monitoring. An environmental monitoring network system covering China's offshore bays, islands and reefs, beaches, nature reserves, aquatic germplasm resources reserves and aquaculture waters has been initially formed, and the bulletin on the state of China's fishery ecological environment has been issued regularly. A national pollution control monitoring network for agricultural products was established to carry out the investigation of heavy metal pollution in the producing area.

Third, vigorously promote the scientific application of chemical fertilizers and pesticides. Comprehensively popularize the technology of soil testing and formula fertilization, with an area of 1.4 billion mu, thoroughly implement green prevention and control, set up 150 national green prevention and control demonstration zones, phase out 33 kinds of highly toxic pesticides one after another, and vigorously promote the use of high efficiency, low toxicity, low residues and biological pesticides; carry out the integration of specialized unified control and green prevention and control of crop diseases and pests to promote the pilot construction, and establish a demonstration base In early 2015, the Action Plan for Zero growth in Fertilizer and Pesticide use by 2020 was issued, and the implementation of Zero growth in Chemical Fertilizer and Pesticide use was launched.