1. Introduction
Agriculture is the foundation of the Chinese national economy as it provides materials for both residents and other industry sectors. As China is a large agricultural country, agriculture is vital to both the Chinese government and the people [
1]. Since the Economic Reform and open up in 1978, China’s agricultural economy has achieved great success with most problems that had been associated with insufficient agricultural product supply being solved. In 2017, China’s total grain output reached 617.91 million tons [
2], twice the total grain output of 304.765 million tons in 1978. However, the measures taken to increase agricultural production have resulted in the excessive use of chemical fertilizers and pesticides can no longer meet the requirements of the development of agricultural economy in China under the new situation [
3]. Due to the increase in agricultural pollution, such as chemical fertilizer pollution, pesticide pollution and intensive farm pollution, which has resulted in the bad situation that nitrogen, phosphorus, pesticides and other organic or inorganic pollutant entering the surface water, groundwater, and soil environments through surface runoff [
4]. All these pollutions endanger the environment and the health of residents [
5]. Modern agriculture depends heavily on pesticide use and chemical fertilizer, which have successfully increased productivity but led to increasing concerns regarding the environment and human health [
6]. The promotion of agricultural economy may bring agricultural pollution, and agricultural pollution may restrain the development of agricultural economy. The relationship between them has an impact on the development of agriculture and public health. Therefore, it is necessary to study the relationship between economic growth and environmental pollution as the destruction of the ecological environment can restrict economic development. Chengdu is a core city in the southwest of China. It has a good level of agricultural development and a high agricultural status in the western region. However, there is no analysis of the relationship between the agricultural economy and the agricultural environment in Chengdu in the previous literature. In order to better measure the relationship between agricultural economy and agricultural pollution, realize the sustainable development of the agricultural economy and explore public health issues, this paper use decoupling index [
7] to examine this relationships and provide a new model for the study of economic growth and environmental pollution.
Most research on the decoupling index has involved studying the relationships between economic growth, carbon emissions, energy consumption and other factors. Qiu [
8] believes that promoting the coordinated development of economy and environment is the core of urban sustainable development, so he decoupled the economic growth and resource environment of coal cities. Zhang [
9,
10] and Zhou [
11] believed that China has paid a lot of environmental costs in the past development process. Energy conservation and emission reduction are the top priority. They all used decoupling indices to study economic growth and resource consumption and economic growth and energy consumption. Yi [
12] studied tourism economic growth and ecological environmental pressure issues in geoparks. After studying the economic growth and building land Liu [
13] believed that the dependence of economic growth on construction land resources is gradually decreasing, and manufacturing industry is an important industry to stimulate China’s economy. The analysis of manufacturing economic growth and energy consumption [
14] shows that the development effect of low-carbon industry produced by technological progress is the best. The decoupling index is also used in the analysis of economic growth and sustainability. Through Zhang’s analysis [
15], it is concluded that the sustainability of China’s economic growth increases with economic growth. Long [
16] refers to resource consumption and environmental pollution as ecological loss and analyzed the economic growth, ecological loss and welfare levels in the process of urbanization. The remaining scholars use the decoupling index to analyze the relationship between economy and environment, such as the impact of economic, energy and environmental factors on eco-efficiency performance indicators [
17], economic growth and groundwater consumption [
18], economic growth and environmental pollution [
19], economic growth and environmental pressure [
20], and economic growth and environmental conditions [
21].
Other research on carbon emissions or energy consumption have examined the relationships between industrial growth and carbon emissions [
22], industrial development and energy consumption, carbon dioxide emissions [
23], regional high-tech industry agglomeration and the ecological environment [
24]. These articles are based on the impact of the development of an industry on carbon emissions. Some scholars look for the relationship between carbon emissions and urban development. Xiang [
25] studied the urbanization and the associated carbon intensity and concluded that urbanization was rising and carbon emissions were declining. From the environmental point of view are environmental regulations and carbon emissions [
26] and regional welfare levels and natural consumption [
27]. The remaining scholars studied it from the perspective of economic development or transportation, including economic growth and traffic carbon dioxide emissions [
28], industrial carbon emissions and economic growth [
29], carbon dioxide emissions and total electricity generation [
30], transportation carbon dioxide emissions and economic growth [
31], and carbon dioxide emissions and economic growth in the maritime industry [
32].
In summary, the decoupling index has been widely used to examine economic and ecological relationships in industry, tourism, manufacturing, high-tech industries and other fields. However, that has been little research that has used the decoupling index in agricultural relationship studies even though it is suitable for examining the relationships between agricultural economic growth and agricultural pollution. Past studies have generally chosen carbon dioxide emissions as the measurement criterion for environmental pollution, but have failed to consider pollution-related agricultural indicators, such as pesticide and agricultural fertilizer use.
Therefore, from the perspective of agriculture, this paper obtains the data of agricultural economy and agricultural pollution in Chengdu Statistical Yearbook [
33], and puts forward a new evaluation system to evaluate the relationship between agricultural economy and agricultural pollution with the method of decoupling index.
4. Discussion
4.1. Results Discussion
Pesticide use contributes to increased agricultural production and improved product quality, but overuse or abuse of pesticides has been related to negative externalities such as human health effects and external ecological effects [
6]. Heavy metals may be added to soils in agricultural fertilizers and pesticides, soil amendments, or organic fertilizers [
37].
The decoupling index for Chengdu from 2009–2012 was found to be in a stable state in terms of pesticide use and per capita gross agricultural production values there was a “strong decoupling” state for three years, which indicated that during this period, the use of pesticides was declining with the economic growth; that is, the increase in the agricultural economy during this period did not result in much agricultural pollution. In 2013, although the use of pesticides was still declining, there was a “declining decoupling” state due to the negative growth in per capita agricultural production in Chengdu in this year. After 2013, the per capita gross agricultural production in Chengdu was annually increasing. The use of pesticides rebounded in 2016, but for the rest of the year was still decreasing; therefore, the use of pesticides and the per capita gross agricultural production values in 2014, 2015 and 2017 had good “strong decoupling” and only one “expansive negative decoupling” in 2016.
The fertilizer application and per capita gross agricultural production decoupling index was fluctuating with no obvious upward or downward trends. From 2009–2012, as the agricultural chemical fertilizer use declined gradually and the per capita gross agricultural production rose, the decoupling index had a short downward trend. In the last four years, two years had an ideal “strong decoupling” state. From 2012–2015, between 15 and 16 t of agricultural chemical fertilizer was used and the annual decline was not significant. The per capita gross agricultural production value began to rise after the decline in 2013, resulting in ideal “strong decoupling” state in 2014 and 2015. In 2016, the agricultural chemical fertilizer use increased sharply to more than 18 tons, which was significantly larger than the growth in the per capita gross agricultural production value; therefore, there was “expansive negative decoupling”.
The agricultural plastic film use and per capita gross agricultural production were also found to have a fluctuating trend, most of which indicated that there was a “weak decoupling” situation, with only one year indicating a “strong decoupling” ideal state, and the remaining four years being unsatisfactory. This was because except for 2017, agricultural plastic film use was increasing. In 2010 and 2014, the growth in agricultural plastic film use exceeded the growth in per capita gross agricultural production; therefore, overall, there were two years of “expansive negative decoupling” with the other years showing “weak decoupling” states.
4.2. Results Analysis
The pesticide use and per capita gross agricultural production decoupling index was relatively optimistic, with six “strong decoupling” years as the pesticide use was decreasing and the per capita gross agricultural production was increasing in most years, which indirectly indicated that the growth in the agricultural economy had little effect on agricultural pollution. The fertilizer use rate had a parabolic change from 2008 to 2017, a sharp rise (2016), and a sharp drop (2012), which resulted in an overall fluctuation in the decoupling index. However, because of the annual increases in the economy, the chemical fertilizer use had a short period of “strong decoupling” after each sharp rise or fall. The increasing use of agricultural plastic film has aggravated agricultural pollution. However, due to the reduction of the other two indicators, the relationship between agricultural pollution and agricultural economy shows a healthy and coordinated state. Agricultural pollution has not increased as a result of the growth of the agricultural economy.
5. Conclusions
This paper is devoted to exploring the relationship between agricultural economic development and agricultural pollution, and discussing whether it endangers public health. Therefore, the main innovations of this paper are as follows. The relationship between economic growth and environmental pollution was studied from an agricultural perspective in Chengdu, a core agricultural city in Western China, using a decoupling index to explore the key factors affecting the decoupling effect and to identify the direct relationships between the agricultural economy and agricultural pollution. A new model for measuring agricultural economy and agricultural pollution is proposed and validated with the data from 2008–2017. The following conclusions were drawn from the analyses.
The agricultural economy in Chengdu, Sichuan Province, China was found to be developing each year and the agricultural pollution indicators had variable changes. The use of pesticides has been declining for almost a decade. The decoupling index for pesticide use and per capita gross agricultural production showed ideal state of “strong decoupling” in six years. From 2009–2017, the decoupling index of pesticide use and per capita gross agricultural production increased from 0.065743–1.597385, and its decoupling state gradually transited from weak negative decoupling to stable strong decoupling. The decoupling index for agricultural chemical fertilizer use and per capita agricultural production which showed “strong decoupling” in five years was also in a relatively ideal state. The value of it decreased from 1.028854–(−0.512702), while its state changed to strong decoupling. Although the chemical fertilizer use showed a parabolic changing state over the ten years, after each sharp rise and fall, it was in a gentle decline, which meant that there were “strong decoupling” states in some years. However, in recent years, the use of plastic film has shown a bad trend with its value of decoupling index changed from −0.380824–(−0.250250). Because of the increase in plastic film use, there were some “strong negative decoupling” years and some “expansive negative decoupling” years; however, around 50% of the time, the growth rate in plastic film use did not exceed the growth rate in the per capita gross agricultural production, which was why there were “weak decoupling” states for half the time. Generally speaking, the agricultural pollution in Chengdu was declining slowly, which coupled with the annual increase in the agricultural economy, indicated generally healthy and ideal trends. Therefore, the factor changes indicated that the main pollution indicators and the agricultural economic indicators were showing a relatively ideal trend. This shows that the use of pesticides and fertilizers in agricultural development in Chengdu has been well controlled. Although agricultural plastic film usage had an upward trend, the agricultural economic indicator growth was faster than the agricultural pollution indicator growth, which was an ideal decoupling index relationship. The use of pesticides and fertilizers has increased agricultural productivity, while it has a negative impact on public health. Pesticides and fertilizers can cause water, soil and air pollution, add heavy metals to the soil and may further cause food security problems. The situation of agricultural pollution in Chengdu has not worsened with the development of agricultural economy. Effective control of agricultural pollution in Chengdu will have a positive impact on public health.
The relationship between the agricultural economic development and public health needs to be explored to determine the impact of the changes in the regional agricultural economy and agricultural pollution on resident health and food security. The influencing factors for the changes in the agricultural pollution indicators also need to be further explored.