1. Introduction
Chinese agricultural growth has long depended on rising input intensity [
1], leading to resource inefficiency and environmental degradation [
2]. The widespread use of chemical fertilizers, pesticides, and fossil fuels is a major factor contributing to current agricultural pollution [
3,
4]. According to recent World Resources Institute data, agriculture accounted for 12.16% of global greenhouse gas (GHG) emissions in 2021; in that year, China’s agricultural emissions totaled 0.634 Gt CO
2-eq, representing 10.81% of the global agricultural total. ANSP poses another major challenge. The Second National Pollution-Source Survey Communiqué reported that agriculture was responsible for 49.77% of national chemical oxygen demand (COD), 46.52% of total nitrogen, and 67.21% of total phosphorus discharges in 2017, making it the principal COD and nutrient contaminant source. Furthermore, the China Council for International Cooperation on Environment and Development estimates agriculture contributes about 17% of China’s overall GHG emissions, underscoring its significant role in national carbon output growth. Recently, emerging green production technologies have shown promise in improving productivity while protecting ecosystems [
5,
6]. Integrated sustainable farming systems can deliver 2.32- to 2.35-times higher economic returns and reduce ANSP by 10.21–59.01% compared to monoculture [
1]. However, large-scale deployment of these approaches demands continued innovation, considerable investment, and broad societal coordination.
Amid these challenges, research attention to agricultural eco-efficiency (AEE) in China has grown. Existing literature focuses on three main areas: evaluation methodologies, national/regional evolution and distribution of AEE, and factors shaping efficiency. Methodologically, SFA—a parametric method that decomposes deviations from the frontier into inefficiency and random error—accounts well for stochastic effects, improving accuracy, but typically handles only single-output cases and may suffer from multicollinearity [
7]. DEA, a nonparametric benchmark approach [
8], is suitable for multi-input/output analysis; however, basic DEA often ignores undesirable outputs and redundancies [
9]. The data envelopment analysis slack-based measure (DEA-SBM) model [
10] overcomes these drawbacks and slack variables for a more holistic efficiency assessment. Nationally, China’s AEE has increased markedly in recent years, with greater spatial agglomeration [
11,
12,
13]. From 1978 to 2017, national AEE rose from 0.405 to 0.713—a 76% increase. Notable regional heterogeneity exists, with the northeast, east, and south exceeding the national average [
14]. While provincial disparities persist [
15], they show a general decreasing trend over time [
11,
16]. Key determinants of spatial differences include energy and water inputs and carbon emissions [
17]. Furthermore, spatial spillover effects among provinces have shifted in recent years, with diminishing negative and strengthening positive correlations [
18]. At the regional and local scales, studies reveal considerable variation and offer targeted insights. Zhang and Jin [
19] found significant intra-provincial differences in AEE across 44 Liaoning counties; Deng and Gibson [
20] highlighted trade-offs between agricultural output and urbanization in Shandong, signaling the need for localized technological adjustments to bolster AEE. Similarly, Yang et al. [
21] showed that socio-economic development, increased technology investment, emission reduction, and improved pollution controls all positively influence land-use eco-efficiency.
Cities, the fundamental units in global competition, are becoming the core of the global economy as it shifts to a space of flow, highlighting their growing significance. Additionally, they have transitioned from standalone cities to integrated urban agglomerations [
22,
23,
24]. As a result, these urban agglomerations have become core areas driving national innovative transfer and economic development [
25]. With their continuous growth in both scale and influence, urban sprawl emerges and agricultural land decreases. Consequently, farmers begin to migrate, agricultural markets expand, and consumer demand for green agricultural products increases [
26]. This change necessitates higher requirements for agriculture production: Beyond improving production efficiency and resource utilization, we must also consider environmental protection to achieve sustainable agricultural development.
Agricultural technology innovation is a key factor that propels green development in agriculture. Additionally, it has a knowledge spillover effect. A higher level of informatization and openness accelerates the diffusion of agricultural technology innovation between industries and regions. Moreover, the spillover provides possibility for increasing agricultural ecological efficiency (AEE) on a larger scale [
27]. Each city within a cluster establishes an intensive network of agricultural technology innovation with other cities based on cooperation and communication, promoting the sharing of agricultural technology, experience, and resources [
28]. This drives faster innovation in agriculture and advances the modernization of traditional production systems in urban agglomerations, resulting in improved energy use, reduced consumption, and lower emissions [
29]. Through technical communication and the demonstration effect, especially, agricultural technology innovation within urban agglomerations facilitates diffusion and sharing and reduces environmental burden. The form of the technology innovation network inspires us to cooperate, conduct innovation research, consolidate resource advantages, and accelerate the research, development, and application of agricultural ecological technology. The agricultural technology innovation network within urban agglomerations typically relies on advanced technologies to achieve refined management of the agricultural production process and provide decision support, ensuring the health of the agricultural ecosystem and improving agricultural ecological efficiency.
Previous studies examining the link between agricultural technology innovation networks (ATINs) and AEE have mainly focused on several key areas. Firstly, research emphasizes the influence of ATIN in promoting the dissemination of technology. By analyzing the social network structure and information flow paths, it investigates how inter-node connections within the network affect the spread of agricultural technologies, highlighting the critical role these networks play in improving farmers’ willingness to accept and adopt new technologies [
30,
31,
32]. Additionally, emphasis is placed on how ATINs optimize resource allocation and improve management efficiency. By analyzing the flow of information and resources within ATINs, research explores the network’s impact on resource utilization efficiency and agricultural production management, thus highlighting how technology innovation networks contribute to enhancing agricultural ecological efficiency [
33,
34]. Several scholars also focus on how innovation networks promote the development of ecological agriculture. By analyzing the dissemination and application of eco-friendly technologies within the network, they examine the impact of technology innovation networks to improve soil quality and protect biodiversity [
35]. However, there is a scarcity of literature studying the impact of ATINs within urban agglomerations on AEE from the dimensions of urban agglomerations and the perspective of urban–rural interaction. Urban agglomerations serve as important spatial carriers for regional innovation ecosystems, with their internal urban areas being the main sources of technological innovation. In contrast, the vast rural areas within urban agglomerations provide a broad market space for the transformation and application of innovative achievements. Additionally, it is noted that some agricultural technology innovations, such as crop breeding and soil improvement technologies, are regionally adaptable, making them difficult to disseminate across national, provincial, or different industrial boundaries. Therefore, researching the diffusion of agricultural technology innovations within the scope of urban agglomerations can effectively “capture” the diffusion effects of such technology innovation. In summary, studying the impact and mechanisms of ATINs within urban agglomerations on agricultural ecological efficiency (AEE) is of great significance.
The current scholarship on AEE appears to have three potential areas of insufficiency. First, most studies operate at the national scale [
11,
12], at the provincial scale [
15], or within a single macro-region such as the Yangtze River Economic Belt [
23], while analyses that follow the spatial–temporal evolution of AEE across urban agglomerations remain rare. Second, in calculating AEE, researchers typically define “desired outputs” as total agricultural economic value [
19,
36] but seldom include measures that reflect ecosystem service value or the sector’s carbon-sink capacity, which leaves the efficiency portrait incomplete. Third, although existing work documents the benefits of green technologies [
6,
23], detects spatial spillovers among neighboring areas [
17], and probes the urban–rural dynamics that shape agricultural ecological efficiency [
20], the role of technology innovation networks within urban agglomerations and their attendant spillover channels remains largely unexplored.
To address these gaps, the present study advances in three stages.
Stage 1: We build a comprehensive AEE index system that makes ecological contributions explicit. Land, labor, irrigation water, and chemical fertilizer constitute the inputs; total agricultural output, agricultural carbon sequestration, and agricultural ecosystem service value serve as desired outputs; and agricultural carbon emissions and non-point-source pollution are treated as undesirable outputs. City-level AEE is then estimated with a super-efficiency DEA model that accommodates undesirable outputs. It should be emphasized that city-level AEE encompasses both the agricultural efficiency of urban areas and the AEE of rural areas within city administrative divisions.
Stage 2: A modified gravity model is applied to map the spatial network of agricultural technology innovation within urban agglomeration. Visualization tools track the co-evolution of the AEE and the agricultural technology innovation networks (ATINs) in the Urban Agglomeration in the Middle Reaches of the Yangtze River, revealing key developmental patterns.
Stage 3: A spatial Durbin model is employed to quantify the impact of the ATINs on city-level AEE. The results uncover heterogeneous effects across core, sub-core, and peripheral cities, and demonstrate that digital infrastructure, agricultural finance, and industrial scale each positively moderate the efficiency gains generated by networked innovation.
This paper contributes the following three folds. First, it incorporates agricultural ecological values, such as agricultural carbon sequestration, into the expected outputs, thereby optimizing the measurement methods for AEE. Second, the analysis focuses on the dynamic development trends of AEE and ATINs in the Urban Agglomeration in the Middle Reaches of the Yangtze River (UAMRYR), summarizing patterns of evolution. Third, based on the regional innovation theory, it explores theoretical mechanisms by which ATINs within urban agglomerations affect AEE. Additionally, by constructing a spatial Durbin model, it empirically analyzes the impact of ATINs on city-level AEE. It examines the specific effects of three influencing mechanisms: informatization level, agricultural finance, and agricultural industrial scale.
2. Theoretical Analysis
Urban agglomerations serve as important spatial carriers for regional innovation systems. Within urban agglomerations, individuals in many industries who are involved in innovation, such as knowledge and technology producers (research institutions, technology intermediaries, and educational organizations), knowledge users (enterprises, suppliers, and customers), and regional policymakers engage in competition and cooperation through technology innovation networks to promote technology innovation and diffusion [
37]. ATINs can extend the impact of technological externalities and, through inter-regional technology transfer, alleviate the limitations of traditional agricultural production techniques in relatively backward areas inside the urban agglomeration, significantly enhancing local agricultural production efficiency. Moreover, agricultural innovation networks facilitate a more accurate assessment and utilization of resources by agricultural producers through information sharing and cooperative mechanisms, thus alleviating information asymmetry and market failure in agricultural production to a certain extent [
38]. Cooperation and information sharing among agricultural producers within urban agglomerations cultivate a positive cycle of technology innovation and experience sharing, leading to improved AEE and better ecological environments across the agglomeration [
39]. In addition, ATINs within urban agglomerations provide a broader space for innovation incentives. Through technological exchange and cooperation, agricultural producers can more easily access technological support, thereby driving agriculture towards more ecologically friendly and efficient practices and enhancing AEE [
40,
41]. Given these insights, the study formulates research Hypothesis 1.
Hypothesis 1: The urban agglomeration’s agricultural technology innovation network can significantly enhance AEE, with the network’s spatial spillover effect further strengthening this positive impact.
A regional innovation ecosystem is known as a network of relationships formed through competition and cooperation among regional innovation entities within a specific innovation environment, where the flow of innovative elements such as matter, energy, and information are the main content of network connections [
42]. Improved levels of informatization can accelerate the circulation of innovative factors within a region, enhancing the efficiency of technology network innovation and diffusion. More specifically, the ability of internet information to transcend time and space makes it easier for agricultural technology to break through urban boundaries, resulting in cross-regional technological spillovers. As the level of informatization in urban agglomerations increases, the circulation of innovative elements such as information, talent, and capital among cities is accelerated, strengthening the innovative connections among cities [
43,
44]. The advancement of informatization in rural areas of urban agglomerations enhances the interaction of information between cities and the countryside, facilitating the diffusion and application of advanced agricultural technologies in rural areas [
45]. The increasingly diversified channels of information dissemination also alleviate the information asymmetry between transaction parties to some extent, reducing the cost of technology transactions. At the same time, informatization can provide more abundant and accurate data support to boost the efficiency of innovation resource allocation [
46] and enhance the level of collaborative cooperation among participants in the agricultural technology innovation network, further promoting the spillover of agricultural innovation technology. Given these insights, the study formulates research Hypothesis 2.
Hypothesis 2: Informatization enhances the technology innovation capabilities and technological diffusion of urban agglomerations, strengthening the spatial spillover effect of the agricultural technology innovation network.
In rural areas, financial markets are characterized by relatively strong information asymmetry and high transaction costs, leading to insufficient credit supply related to agriculture and presenting considerable financing constraints for the development of agriculture and rural areas [
47]. The development of agricultural finance can promote agricultural technological advancement and strengthen the inter-regional diffusion of agricultural technology, thereby narrowing the technology gap and increasing the green total factor productivity in agriculture [
48]. Agricultural financial institutions utilizing their industry resources and social influence provide necessary financial support and consulting services for new agricultural technologies to facilitate the application and promotion of agricultural innovation technologies within urban agglomerations [
49]. At the same time, by integrating their own information resources and breaking down information barriers between enterprises and farmers, they can offer better cooperation opportunities and development spaces for various market entities within urban agglomerations [
50]. Given these insights, the study formulates research Hypothesis 3.
Hypothesis 3: The development of agricultural finance has improved agricultural market entities’ ability to receive and apply new technologies, strengthened the spillover and diffusion of agricultural technology through innovation networks, and helped enhance AEE.
The scale of the agricultural industry affects the spillover of technological innovation, particularly its external effects on innovation technology [
51]. A larger agricultural industry implies the participation of more farmers, enterprises, and consumers in agricultural production and consumption activities, leading to tighter connections between farmers and enterprises and smoother information flow. This will be beneficial for the research, development, and application of agricultural science and technology. Technology enterprises and research institutions can create agricultural technologies that are better tailored to market needs, thereby reducing costs and enhancing efficiency [
52]. The expansion of the agricultural industry accelerates the formation of a unified technology market within urban agglomerations. To maintain their competitive advantages, agricultural technology innovation enterprises will increase investment in research and development. This will further promote the development of the agricultural technology innovation network within urban agglomerations and have a positive impact on the enhancement of AEE within the agglomerations [
53]. Given these insights, the study formulates research Hypothesis 4.
Hypothesis 4: The expansion of the agricultural industry strengthens the technological network connections within urban agglomerations, enhances the competitiveness of technological innovation, promotes the development of innovation networks, and has a positive effect on enhancing the AEE of urban agglomerations.
Based on the above theoretical analysis, the mechanism analysis framework of the article is shown in
Figure 1 as follows:
7. Conclusions
This paper focuses on the UAMRYR as the research object, applying a modified gravity model and social network analysis methods to analyze the spatial pattern evolution of the agricultural technology innovation network in these agglomerations. It also constructs an agricultural ecological efficiency evaluation indicator system and employs a super-efficiency SBM model with undesirable outputs to measure the AEE of the cities in the agglomeration from 2001 to 2023. On this basis, a spatial Durbin model is built to explore the impact of the agricultural technology innovation network on agricultural ecological efficiency in the UAMRYR. The following conclusions are drawn: (1) Increasing a city’s degree centrality in the agricultural technology innovation network can significantly boost local agroecological efficiency and positively spill over to surrounding cities, enhancing their agroecological efficiency, as well. (2) Within the network, substantial heterogeneity is observed in both direct (influence on a city’s own agroecological efficiency) and spillover (influence on neighboring cities’ agroecological efficiency) effects across various city tiers. Central cities display significant direct and spillover effects, while sub-central cities exhibit significant direct effects but do not show notable spillover effects. In contrast, peripheral cities present insignificant direct effects, yet demonstrate pronounced spillover effects. (3) The level of urban informatization, agricultural finance, and the scale of the agricultural industry effectively enhance the spatial spillover effect of the agricultural technology innovation network, which further promotes the improvement of agroecological efficiency.
This paper draws the following policy insights: (1) One of the key factors to improve agroecological efficiency is the technological innovation of cities, and we should solve the problem of improving agroecological efficiency from the perspective of urban–rural interaction and pay attention to the agroecological innovation of cities. Increase the investment in innovation, pay attention to science and technology innovation talents, and improve the quantity and quality of urban agricultural technology innovation. (2) Strengthen the linkage of agricultural technology innovation among cities within the city cluster, promote the flow of innovation factors, and promote the optimal allocation of innovation results within the city cluster. At the same time, the main effect and spillover effect of cities at all levels in the agricultural technology innovation network are heterogeneous. Therefore, the spillover effect of the network’s central city should be strengthened, and the network’s edge cities should be encouraged to enrich the application scenarios of agricultural technology innovation and improve their ability to localize and apply technological innovation achievements. (3) Strengthen the application of information technology in the field of agriculture and promote the dissemination and diffusion of agricultural technological innovation among cities and between urban and rural areas. Establish and improve the transformation and application systems of agricultural technological innovation achievements at the level of city clusters and utilize the advantages of agricultural scale to provide a broad market for the application of new technologies. Strengthen support and guidance for the development of agricultural finance, encourage financial institutions to invest funds in agricultural innovation projects, and promote the in-depth integration of agricultural innovation technology and finance.
This paper may have two shortcomings: First, agricultural ecological efficiency is influenced by multiple factors, and there may be complex interactions between different factors that were not fully considered in the paper. Second, the research is limited to the UAMRYR, so the influence of factors from other regions might be overlooked. In the future, the researchers plan to proceed by focusing on three aspects: First, analyze in-depth the role and impact of farmers living in the agricultural technology innovation network within urban agglomeration to examine the correlation between farmers’ participation and the improvement of agricultural ecological efficiency. The researchers will study farmers’ attitudes towards and preferences for different types of technology, and how to enhance farmers’ participation in and acceptance of technology, aiming to encourage active involvement in the technology innovation network and improve agricultural ecological efficiency. Second, study the characteristics of ATINs within different urban agglomerations, including participant and information flow paths. By comparing the characteristics and agricultural ecological efficiency of different urban agglomerations, the researchers will discuss the reasons for these differences. This is expected to provide references for better promoting agricultural ecological efficiency. Third, analyze government policy support and promotion measures in the agricultural technology innovation network within urban agglomeration and the impact of these policies on agricultural ecological efficiency, with a specific focus on how government policies affect agricultural technology transfer, knowledge sharing, and innovation input.