The quality of arable land in China: contaminated soil covers 1/5 of arable land

In the past 50 years, China's agriculture has gone through a high investment, high yield, high-speed and high resources and environmental costs of the road; the future agricultural development, will face the shortage of resources, ecological deterioration, technology weakness, technical innovation and other difficult problems "the quality of arable land at present" low, fee, Pollution ' problem is serious, and the arable land is decreasing, if can not ensure 1.8 billion mu of arable land red line, can not solve the problem of arable land quality, will threaten the national food security.　　Dr. Zhang Weiri, deputy director of agricultural resources and Agricultural Regionalization Institute of the Chinese Academy of Agricultural Sciences, is very anxious about this. In an interview with "Outlook" Newsweek, the first-class leader of the Chinese Academy of Agricultural Sciences, a long-time expert on soil fertilizers and agricultural non-point source pollution, repeatedly stressed to our correspondent: China's per capita arable land resources are scarce, leading to food security and environmental problems, and " Understanding soil and soil related resources and environmental conditions, and accurately mastering the state of soil fertility and environmental quality will still be the important basis to deal with the global financial crisis and climate change, and to realize China's food security, environmental security and sustainable development. According to Zhang Weiri, China's first and second soil censuses were carried out in the 50 and early 80, and in the past 10 years, national projects such as soil Pollution Survey, geological element survey, farmland grading, land Force survey and evaluation, farmland soil nutrient status survey, etc.　　It has played a role in understanding soil fertility and environmental quality in different periods in China. "But these surveys, to varying degrees, there is insufficient processing of investigation data, preservation and utilization is difficult to continue, cross-regional, cross-sectoral, interdisciplinary scientific data sharing is difficult to achieve many aspects of the problem." Zhang Weiri said, "The most important, this kind of investigation belongs to the basic work of science and technology, not only the workload is big, professional strong, difficult, more need scientific method, professional team, should rely on professional institute, long-term research." Relying on the current tactics is unscientific, the state invested a lot, but the effect is not ideal. "Agriculture will face severe challenges in the next 20 years." As we all know, soil is the basis for human survival, the most important resource for developing economy and agriculture, and the most important basis for the ecological system of farmland is to dissolve the life of urban and rural areas, produce waste and maintain carbon, sulfur and phosphorus. The shortage of arable land resources in China is an indisputable fact, not only the per capita cultivated area is less (only 1.43 mu), and because of the large population, many unfavorable agricultural soil is reclaimed for farmland, the overall quality of arable soil is low, and the middle and lower-yielding farmland soil is 65%.　　Dai Jingrui, a professor of Chinese Academy of Engineering and Chinese Agricultural University, has admitted that China's agriculture will face severe challenges in the next 20 years.　　During the "two chambers" academician Congress held in early June this year, Dai Jingrui the grim situation facing the future agricultural development to five major challenges, including population growth, arable land reduction, water shortage, ecological environment deterioration, the impact of global climate change on agriculture, and so on, one of the most important challenges is the farmland problem. "China Engineering Science and technology medium and long term development Strategy research", led by China Academy of EngineeringResearch on the project of Agricultural Science and technology field group in the past 50 years, China's agriculture has gone through a high investment, high yield, high-speed and high resources and environmental costs of the road, the future of agricultural development, will face the shortage of resources, ecological deterioration, technical weakness, lack of technological innovation and other difficulties, not only to ensure the food security of 1.6 billion people, It is very difficult to realize ecological security, environmental security and sustainable development.　　The trend of population growth and consumption increase is irreversible, which is the first major challenge for agriculture in the next 20 years. Dai Jingrui said that the future of our population is expected to grow by 10 million per cent a year, the 2030 is likely to reach 1.6 billion people, living standards and urbanization level will continue to stimulate the growth of food demand, by 2030, China's food demand will reach 617 million tons, the total grain production needs to increase by more than 20% on this basis, meat, eggs, milk also need to increase 24%, 28%, 205% respectively. Therefore, to ensure food security is the primary task of China's agriculture, is the most important agricultural production. At the same time, agricultural product quality safety problem is outstanding. Because of the large use of pesticides, fertilizers, nitrite, heavy metals and other toxic substances into the food chain, endangering human health.　　Feed safety and animal husbandry safety and control are also important links of agricultural product quality and safety. "The lack of quality is equally worrisome" farmland is the second biggest challenge facing agriculture. Although our country put forward the strict farmland protection system and the total amount of arable land dynamic balance system, but the future arable land reduction will be an inevitable long-term trend, this trend can only slow down and can not be curbed, 1.8 billion acres of arable land red line facing the most severe test.　　Currently, our population is less than 0.1 hectares, less than the world average of 1/2, less than 1/4 of the developed countries, only 1/6 in the United States, 1/9 in Argentina, 1/14 in Canada. "It is important to protect the quantity of arable land, but the quantity without quality is equally worrisome." If the number of 1.8 billion mu of arable land remains unchanged, but the distribution status and quality of the situation from concentration, continuous film, quality gradually to broken, sporadic, inferior to the transformation of the cumulative damage will be very serious, and at present, some places have appeared this kind of sign.　　"A senior fellow told the Lookout News Weekly," he said.　　The Ministry of Land and Resources released December 24, 2009 in China's history of the first farmland quality grade survey and evaluation results, "China's farmland quality grade survey and evaluation" also showed that the quality of arable land in China is generally low.　　This 10-year, more than 1.3 million-person survey is based on natural conditions, farming systems, infrastructure, agricultural production technology and input factors such as comprehensive investigation and evaluation, the national arable land evaluation of 15, 1, such as the best quality of arable land, 15 of the worst. The survey shows that the average quality of arable land in the country is 9.80, etc. The proportion of the total cultivated land in the whole country is 2.67%, 29.98% and 50, which are excellent, high, medium and low.64%, 16.71%. National arable land below average and other 10 to 15 of the survey and assessment of the total area of more than 57% of the national production capacity of more than 1000 kg/mu of arable land accounted for only 6.09%.　　The overall quality of arable land in China is obviously low. A geologist who did not want to be named also confirmed that China's annual urban development and infrastructure construction occupies a large number of high-grade arable land, and the supplementary arable land is mainly distributed in the areas of water heat, location, relatively poor terrain conditions, the overall quality is not high. "High-grade arable land loss too fast, the level of supplementary farmland is low, shoddy situation is very serious, the overall decline in quality of arable land, has seriously affected the productive capacity of arable land, threatening the national food security." In this sense, it is not enough to keep only 1.8 billion acres of arable land, it is necessary to ensure the quality of arable land and ensure the steady improvement of arable land productivity. "The soil foundation of arable land has been declining, Zhang Weiri said in an interview before the 80 's, the main problem of restricting arable land productivity in China was the lack of soil nitrogen and phosphorus, with the increase of fertilizer input and crop yield in the past years, the improvement of the supply of nitrogen and phosphorus in arable soil," low, cost and dirty "　　has gradually become a new round of the core problem of farmland soil quality in China. Zhang Weiri explains that the "low" here mainly refers to the low base of the force. The basic ground force refers to the yield that farmland can obtain by its own fertility when it is not fertilized.　　High-quality arable land is the result of long-term development or cultivation for many years, usually deep soil, rich in organic matter, water oxygen heat coordination, water retention and fertilizer, drought tolerance and waterlogging, high yield and stability, the foundation of the force. According to the Soil and Fertilizer Institute of China Academy of Agricultural Sciences in recent years, field location experiments and surveys show that unreasonable tillage, excessive planting, extensive investment in agricultural chemicals and aging of ditch facilities in the major agricultural areas of China have resulted in the thinning of farmland soil, the imbalance of nutrients and soil compaction,　　Soil biological characters degeneration, soil acidification, latent fertility, salinization increase, drought-resistance drainage capacity is poor, the soil foundation of arable land has been declining. Due to the long-term use of shallow ploughing machinery and the use of organic fertilizers, the active soil layer of farmland has become shallower and the root of crop is difficult to be tied down. Because of the lack of scientific fertilization technology suitable for farmers, the unreasonable proportion of fertilizer nitrogen, phosphorus and potassium is still common in all major agricultural regions of China. In the intensive farming area, which accounts for about 20% of the farmland area, the nitrogen and phosphorus fertilizer is used severely, the average fertilizer yield of single season crop is 569~2000kg/hm2, and the nitrogen utilization rate is only about 10%. Due to the extreme imbalance of nutrient supply, crop pests and diseases, agricultural pesticide dosage increased significantly, resulting in this part of China's most productive farmland soil salt damage, serious acidification, structural damage, pesticide residues, soil pollution problems are very prominent, soil biological characteristics, health function seriously decline, productivity can be greatly reduced. Farmers in Shandong, Yunnan and other provinces have to take deep ploughing subsoil, soil and even change plots to slow down production.。 From the 80 's in the last century, the rural arable land from the collective large area of management into one household management mode, the farmland management unit becomes small, the use right change frequently, to the farmland capital construction neglect, in many areas the farmland ditch is in disrepair, although the state invests completes the large-scale water conservancy project construction including the river channel transformation, because the farmland ditch aging,　　It is difficult to effectively carry out drought and waterlogging in farmland. The only "increase in fertilizer and low yield" type "fee" is due to the decline in the ground strength of the arable land, water retention and fertilizer performance, water resistance and fertilizer performance, on drought, nutrient imbalance more sensitive to the level of management of farmland more demanding, so the soil more "eat fat, eat workers, draft, increase production or maintain high yield, mainly rely on a large number of use of fertilizers, pesticides,　　Agricultural film and irrigation water ", resulting in" fee ". Analysis shows that at present in the global high nitrogen fertilizer consumption countries, China is the only "increase fertilizer and low yield" type, 2000-2008 years nine years, the total amount of fertilizer than the 90 's increase of 35%, grain yield net increase of 315 kg/ha. Other types are: "Weight loss high yield" type, such as Germany, Israel, the Netherlands, in 2000-2006 years 7 years, the total dosage of nitrogen fertilizer than the 90 decline 9%~26%, grain yield increased by about 500 kg/ha; "Low weight loss" type, such as Korea, Denmark, Britain, In France, under the condition of the decrease of nitrogen and chemical fertilizer, the yield of grain was lower than that of 17%~33% (211~296 kg/ha); "Increase fertilizer and high yield" type, such as Vietnam, Bangladesh, Egypt, Chile, etc., the same period of increase in fertilizer consumption 20%~69%, grain yield net increase of more than　　Up to 1173 kg/ha. "Sewage" is the soil pollution of arable land, which is another major problem in the quality of arable land in China.　　Zhang Weiri said that the pollution is mainly from industrial and urban sewage, farmland pesticides, agricultural films and other chemicals such as ultra-high quantity and unreasonable use, large-scale livestock and poultry farms high environmental hormone content of livestock and poultry manure and waste of unreasonable use. Information provided by authoritative departments shows that at present, the use of pesticides in China has reached 1.3 million tons, is the world average level of 2.5 times times, pesticide-contaminated farmland soil area of 136 million MU, plastic film use up to 630,000 tons, white pollution is very serious; China's livestock and poultry industry has always maintained the momentum of rapid development,　　The number of poultry herds increased 1~2 times every 10, in recent years, the production of livestock manure has reached 3.8 times times the amount of industrial solid waste, in the main production areas of animal husbandry, the local livestock manure and waste produced more often than the local safe carrying capacity of more than a few times or more, resulting in serious soil heavy metals and antibiotics, hormones and other organic pollutants pollution. Polluted soil occupies 1/5 of arable land Zhang Weiri that in recent years, high fertilizer, pesticide dosage of vegetables, flowers, fruit crop sown area of high-speed growth, livestock and poultry aquaculture development in the vast number of farmers to bring benefits, but also brought an unavoidable environmental pollution problems, And will become the main source of agricultural non-point pollution in the future for a considerable period of time.　　Zhang Weiri's Non-point source pollution refers to the water pollution caused by the surface runoff and soil infiltration into the water when the land is polluted, such as fertilizer, pesticide, domestic rubbish, farm animal manure, etc. Since 1993, Zhang Weiri has begun to study the agricultural non-point source pollution in China. Over the past more than 10 years, she has led the research team to nearly 100 counties in more than 10 provinces, completing more than 5,000 field orientation surveys, sampling and testing. The research shows that the degree and breadth of water eutrophication caused by agricultural non-point source pollution in China is far more than that in developed countries. Water pollution caused by agriculture and rural Development has become one of the greatest challenges to sustainable development.　　The results also showed that the polluted soil in China accounted for 1/5 of the cultivated land, and the most polluted farmland mainly concentrated on the best cultivated soil, the densely populated urban surrounding area and the requirement of soil environmental quality should be higher vegetable and fruit planting base. "Dead End" in recent years, on the one hand, with the urbanization, industrialization, urban and rural areas around the irrigation and drainage conditions, after years of cultivation of high-quality arable land by a large amount of increase in the proportion of low and medium-yielding farmland, the overall quality of arable land continued to decline; The unreasonable phenomenon of farmland management and technical measures in rural areas is very common, which leads to the decrease of soil foundation and the poor ability of disaster prevention and mitigation. Zhang Weiri analysis that the current maintenance of high production, mainly by increasing the amount of agricultural chemicals and energy input.　　At present, the average application amount of nitrogen fertilizer in China is still 151%, 159% and 329% in France, Germany and the United States respectively, while the level of farmland grain yield is still 10%-30% lower than those countries. Although our country's rural labor cost is low, but the energy consumption of nitrogen fertilizer is higher than that of developed countries, the production cost of agricultural products is still very high, which makes farmers ' economic benefits difficult to improve, and the international competitiveness of agricultural industry is weak.　　"Zhang Weiri said. Data show that, due to the shortage of arable land reserve resources, the rapid decline in China's arable area, only 1996-2003 years, as a result of construction land and so on, the national arable land reduced by nearly 100 million mu, the average annual reduction of 0.8%.　　According to the forecast, by 2020, the amount of arable land in China will be reduced by 7%, so it is impossible to expand the cultivated area to achieve the growing population's food demand, to achieve 90% of the food security guarantee rate, the grain yield must be increased by 30% on the existing basis. Zhang Weiri not worry, said that the current level of fertilizer use in China has been very high, by the return rate of returns, by increasing the amount of fertilizer input can cause production growth has been near the limit. Since 1998, although our country's fertilizer, pesticide, agricultural film and other agricultural material investment amount has been increasing, but the grain yield has lingered for many years. This further illustrates that, for the continued improvement of our country's food production capacity, "the only way to increase the amount of agricultural chemicals and energy input will be a dead end, and to improve the base of farmland, and the accumulation of grain in the soil, is the inevitable choice of establishing long-term food security mechanism and realizing grain security in our country. "-(reporter Sun Yinglan)