Agriculture refers to an important industrial sector in a national economy, it is an industry that produces food and industrial raw materials by cultivating animal and plant products (Foley et al., 2005). Agriculture is the primary industry. Agriculture includes: farming, fisheries, forestry, animal husbandry and many other industries, the existence of agriculture has a history of more than several thousand years, its existence and development play an important role in the survival of mankind (Ligon and Sadoulet, 2018). Since the 20th century, the development of science and technology has promoted the great development of world agriculture, which has greatly helped solve the problem of hunger and poverty in human society (Foley et al., 2005), but its development has also brought about serious problems such as environmental pollution and ecological disorders. How to solve the problem of poverty and hunger in the world while solving the negative problems brought by agricultural development to the environment, so as to achieve the synergistic development of natural, social and economic sustainability is a very practical research topic. In the first part of this study, it first introduces the research background, motivation and framework of this paper. The second chapter presents the negative impacts on the environment brought about by the development of agriculture today, and finally, it makes suggestions on how to solve these negative effects.
2.0 Main body 主體
2.1 Ecological disorder生態失調
Ligon and Sadoulet (2018) argued that the relationship between agriculture and the environment is negative, and the expansion of agricultural land comes from forest land, which inevitably leads to overexploitation of forests and serious damage to the environment. Eberhardt and Vollrath (2018) used the data during 1961-2000 to analyze the relationship between population, agriculture and environmental pollution in Latin America. They believed that even if the population growth rate slows down, the increase in urban consumption and land overuse will bring huge challenges to the environment, thus policy makers need to take a long-term consideration of sustainable development issues.
With the development of society and economy, the demand for wood, fuelwood and agriculture, grazing land and residential land has increased, resulting in a continuous reduction in forest area (Eberhardt and Vollrath, 2018). The deforestation of trees is severe, causing the loss of the roles that forests and vegetation play in climate regulation, air purification, maintaining diversity of plants and animals, and fixing water and soil. Land desertification and soil erosion are becoming more and more serious. Overgrazing and unsuitable reclamation have caused grassland degradation, which has led to the shrinking of biological populations and the disappearance of biological species.
The agro-ecosystem was destroyed. The crop planting area is too large, and the crop structure is single, and the beneficial sustainable agricultural ecological environment construction is neglected, deforestation and land reclamation, deforestation, overgrazing, over-utilization are found everywhere, which has caused the destruction of vegetation, soil erosion, land desertification, reduction of wild animals and plants, and increased natural disasters to damage the agricultural ecological environment (Ligon and Sadoulet, 2018).
2.2 Abuse of agricultural chemicals and pesticides
Pesticide is put on the market as an important agricultural production material. While creating huge wealth for human beings, it also poses a certain threat to environmental safety and personal health. People use pesticides unscientificly and unrestrainedly, misuse and abuse highly toxic pesticides, which cause residual poisons and pollution to the environment to bring poison to humans and animals. Eberhardt and Vollrath (2018) examined the relationship between agricultural production and environmental pollution in major regions of the world from 1972 to 1992, and found that fertilizers increased food production on the one hand and serious environmental threats on the other, including deterioration of water quality and heavy metal pollution in the soil.
With the rapid increase of the world population and the great development of agriculture since the 20th century, the demand for chemical inputs in agriculture has increased even more (Ligon and Sadoulet, 2018). The data show that the amount of chemical fertilizer applied and the amount of pesticide used in planting areas have increased several times (Ligon and Sadoulet, 2018). The dependence of agriculture on pesticides, fertilizers, herbicides, etc. is increasing. The rational use of chemicals can effectively prevent various pests and diseases to improve the yield and quality of agricultural products, and maintain soil nutrients and soil fertility. Unreasonable use or even abuse of chemicals can increase the amount of greenhouse gas emissions and the amount of pollutants that enter the water and soil, causing damage to tropospheric ozone and eutrophication of lakes and rivers (Björn-Ola Linnér, 2018). The large use of chemical fertilizers causes pollution to rivers, lakes and groundwater resources. The eutrophication of water bodies threatens offshore organisms, and the nitrogen content is too much, causing the nitrite content in vegetables to exceed the standard seriously and posing a threat to human health. Long-term use of chemical fertilizers will destroy the soil structure, causing soil compaction, decreased organic matter, reduced fertilizer efficiency, acidification of the soil, and making a large amount of non-nutritional or toxic components enter the soil to result in a decrease in soil organisms such as earthworms, which ultimately leads to reduced agricultural production. In addition, relevant research has also shown that the efficiency of chemical fertilizer utilization in food production is not high, which is not only a major obstacle to the further increase of grain production, but also an important cause of agricultural pollution.
It is worth noting that the data show that the pollution caused by agriculture, especially the pollution caused by chemicals, even exceeds the pollution brought by industry (Björn-Ola Linnér, 2018). For example, in river pollution, the most pollution of total nitrogen is cause by agriculture, followed by life, then byndustrial wastewater. The pollution of total phosphorus comes from life, followed by agriculture, followed by industrial wastewater.It can be seen that the environmental pollution caused by the use of chemicals cannot be ignored.
2.3 Pollution caused by agricultural waste
In some areas where agriculture is not well developed, agricultural plastic film is still widely used. Agricultural plastic film is mainly made of polyethylene or polyvinyl chloride (Chen, Wen, Wang and Nie, 2017). It has the characteristics of large molecular weight and stable performance. It takes hundreds of years to decompose under natural conditions. Therefore, too much residual film in the soil will seriously affect the physical properties of the soil to destroy the soil structure, and hinder the microbial activities in the soil. The residual film forms a plastic barrier in the soil, which also hinders crop root growth and nutrient, water absorption, resulting in reduced yield (Ligon and Sadoulet, 2018). When the residual film enters the stomach of livestock, it will cause the gastrointestinal function of the livestock to decline. Residual film incineration will pollute the air.
In recent years, livestock and poultry breeding industry has developed rapidly. The annual discharge of livestock manure has increased year by year (Eberhardt and Vollrath, 2018). The problem of livestock manure pollution has become one of the major environmental pollution problems caused by agriculture. Livestock and poultry manure emissions have been equivalent to three to four times of the discharge of industrial solid waste. Livestock and poultry manure are directly discharged without any harmless treatment. These livestock and poultry manure carry a large number of pathogenic microorganisms such as Escherichia coli and parasitic eggs and a large amount of nitrogen, phosphorus and other substances, which not only pollute the environment around the farms, and the improper handling of livestock manure will make the spillage enter the surface or groundwater body, and it will have greater pollution to public living water and river water bodies. When it is more serious, it will make the normal indicators of public water seriously exceed the standard or make the water body of rivers deteriorate, and livestock manure is one of the main sources of eutrophication of rivers and lakes (Ligon and Sadoulet, 2018). In poultry farming, animal manure will inevitably emit fermenting gas, which will have a certain degree of pollution to the atmospheric environment; if animal manure is used as organic fertilizer, the phosphorus, nitrogen and other elements in the feces will gradually enrich in the soil, causing pollution.