Research on the Evolution Relationship between Agricultural Carbon Emissions and Economic Growth in Fujian Province Built on the EKC Model

It is vital to explore the relationship between regional agricultural carbon emissions and economic growth for promoting the research of the agricultural Environmental Kuznets Curve (EKC) in China. Based on this, this research first uses the carbon emissions coefficient method to measure Fujian’s agricultural carbon emissions from 2000 to 2016, and uses the EKC model to explore the evolutionary relationship between regional agricultural carbon emissions and economic growth. Research shows that chemical fertilizers are the main cause of agricultural carbon emissions in Fujian. The agricultural carbon footprints and carbon emission intensity in the research area have not yet met the “inverted U-shape” assumed by EKC. Based on this, the author proposes that Fujian should continue to deepen the adjustment of the agricultural supply-side structure and take the road of green and low-carbon agricultural development. Fujian should implement technology reforms and improve the utilization of fertilizers in agricultural production and other emission reduction measures


Introduction
The changing trend of the dependence of agricultural economic growth on resources and the relationship between agricultural development and the resource environment have little by little attracted widespread attention from the academic community [1]. Statistics show that greenhouse gas emissions from agricultural sources is 24% of the total global greenhouse gas emissions. It can be seen that the control of agricultural greenhouse gas emissions is the actual demand for mitigating the overall air pollution sources, and it is also the basis for achieving sustainable agricultural development [2]. Therefore, it is an urgent to realize the importance of developing agricultural carbon emissions and agricultural economic growth as a whole, and is of great significance to the implementation of ecological civilization construction.
Regarding the current agricultural development and carbon emissions, many scholars have conducted extensive research in related research fields. The research mostly concentrates in the fields of industrial wastewater [3] and energy [4], and relatively few research results involving agriculture [5][6][7]. For example, Bo Li et al. (2019) analyzed the co-integration relationship between agricultural economic growth and agricultural carbon emissions and found that Hubei Province's agricultural economic development, production conditions, and regional development strategies are different, which makes the agricultural carbon emissions gap between regions more and more obvious [8]. Zhang Yafei et al. (2020) analyzed the difference in the relationship between agricultural carbon emissions and economic growth in the two core areas of Xinjiang and Fujian in "the Belt and Road Initiatives" from an agricultural perspective, and the results showed that Xinjiang's agricultural carbon emissions and agricultural economic growth are less responsive than those of Fujian [9]. In addition, Elina et al., (2016) and Robin et al., (2017) conducted in-depth analysis on agricultural emission reduction measures [10][11]. Mohanad et al., (2018) discussed the factors affecting agricultural carbon emissions [12]. However, studies focusing on the relationship between agricultural carbon emissions and agricultural economic growth in the core area of the "Belt and Road Initiatives" have not yet found. In "One Belt One Road Initiatives", Fujian is identified as the "21st Century Maritime Silk Road core area" and as the first demonstration area of national ecological civilization. Its agricultural production must be combined with its location advantages to develop low-carbon agriculture [13].
At present, the development of agricultural economy has entered a new normal, but the situation of agricultural carbon emission reduction is still severe. The government can neither focus solely on the agricultural economy and destroy the ecological environment, nor can the government blindly emphasize environmental protection and abandon agricultural economic development [8]. Thus, it becomes necessary to coordinate both to ensure the sustainable development of the economic, social-ecological environment system. However, through literature review, it is found that most of the research on agricultural carbon emissions uses national data for analysis. The research scope is large, lacks pertinence, and is limited to simple time series data analysis. In addition, as the country's first ecological civilization experimental zone, Fujian Province is one of the first provinces to implement reform and opening up policies. These years, due to its rapid urbanization and industrialization process, coupled with unreasonable resource consumption, human activities, and excessive short-term economic behaviors, it has caused varying degrees of impact on the ecological environment of some parts of Fujian [14]. Based on this, this investigation discusses the relationship between agricultural carbon emissions and economic growth in Fujian Province, reveals its internal effect mechanism, and verifies whether the two elements in Fujian Province conform to the EKC model. It is expected to provide a reference basis for the formulation of agricultural carbon emission reduction policies in Fujian Province, and have certain guides for accelerating the transformation and upgrading of Fujian Province's agriculture and promoting high-quality agricultural development.

Agricultural Carbon Emissions and the Calculation Method of Carbon Emissions Intensity
Agricultural carbon emissions refer to the greenhouse gas emissions directly or indirectly caused by chemical fertilizers, pesticides, energy consumption and agricultural waste resource processing in agricultural production [15]. Taking into account the comprehensiveness and availability of data, analyzing the agricultural land use process and calculating the total agricultural carbon emissions generated by carbon sources such as fertilizers, agricultural plastic films, agricultural diesel and pesticides [16]. Here is the calculation formula: In it, CE is the total agricultural carbon emissions, i is the type of carbon source, C i is the carbon emissions of the type i carbon source, T i is the input of the i type carbon source, and δ i is the carbon emission coefficient of the i type carbon source (Table 1).
In it: ACEI is the intensity of agricultural carbon emissions; CE is the total agricultural carbon emissions; AGDP is the total agricultural output value.

EKC Model
In 1991, American environmentalists Grossman and Krueger introduced the Kuznets curve to the study of environment and economic growth. The theory believes that with the development of economy, the environment first shows a state of continuous deterioration, but when the economy development reaches a certain level, the environment shows a situation of continuous improvement, that is, the change curve shows an "inverted U-shaped" [17], namely Environmental Kuznets Curve (hereinafter referred to as EKC).

Data Sources
All the data in this study are derived from the Fujian Statistical Yearbook over the years. Taking into account the availability, continuity and feasibility of the data, the sample of this study is the 16-year panel data of Fujian Province from 2000 to 2016.  In 2016, the carbon emissions of pesticides were 27.33×10 4 t, accounting for 12.33%. The carbon emissions of agricultural film increased rapidly before 2008, but changed little after 2008. From 2000 to 2016, it increased by 7.00%, which is the fastest growing. In 2016, the carbon emission of agricultural film was 32.34×10 4 t, Accounting for 14.58%. It can be seen that from 2000 to 2016, the carbon emissions of chemical fertilizers in Fujian were the highest, but the growth rate was the slowest; while the carbon emissions of agricultural film were relatively low, but the growth rate was the fastest. This shows that Fujian Province has upgraded and transformed its agricultural structure during this period. Adjustments have changed carbon emissions.

Evolution Analysis on the Agricultural Carbon Emissions and Economic Growth in Fujian Province
The study used comparable per capita GDP (PGDP) based on 2000 as the abscissa, and agricultural carbon emissions (CE) and agricultural carbon emission intensity (ACEI) as the ordinate to determine the EKC between the two. This study was based on SPSS 26.0 as the computing platform for fitting regression. Linear equation, quadratic polynomial equation and third power polynomial equation were under fitting respectively, and the model was selected according to the coefficients of determination and related parameters. Figure 3 shows the scatter Figure  It can be seen that the fitting effect of the third power polynomial equation is the best. However, it can be seen that no matter which equation is used, the relationship between the two in Fujian Province does not conform to the characteristics of EKC, that is, agricultural carbon emissions do not rise first and then fall with the rise of per capita GDP. It can be seen that the fitting effect of the third power polynomial equation is the best. However, it is also true that no matter which equation is used, the relationship between the two in Fujian Province does not conform to the characteristics of EKC, that is, agricultural carbon emissions do not rise first and then fall with the rise of per capita GDP.