Agriculture provides the necessary material basis for human survival and development and is the basic industry that supports the national economy of Cambodia. Under the negative influence of COVID-19, global food security was compromised, and the number of people who went hungry globally maintained an upward trend in 2020 [1
]. At present, due to the influence of the Russia–Ukraine conflict, food production has suffered another setback, leading to increasing global food trade costs. It’s expected that the global demand for food production will double by 2050 [2
], which undoubtedly poses a serious challenge to global agricultural production.
The agricultural production capacity of human beings has significantly improved over time. Improvements in agricultural technologies have led to improved agricultural productivity. The world is witnessing an increasing input of agricultural production factors such as natural resources, labor, capital, and agricultural science and technology. For developing countries, not only can agricultural development become the engine of economic growth, but it can also help avoid major economic risks and maintain social stability [3
However, many developing countries fall into a paradox. They are endowed with a large population and rich natural resources but have an inadequate level of modernization. Historically, the globalization of agricultural crops allowed for the feeding of more people. In many developing countries, the lack of internal impetus for modernization, corruption, and limited governance further prevent such countries from taking advantage of globalization while addressing domestic social issues, such as poverty and education.
By relying solely on foreign investment as the external impetus, many resources are allocated to the areas that possess locational advantages in these countries, such as in terms of political, transportation, and natural resources. However, these areas, often with pre-modern infrastructure and institutions, have not yet helped to lift these nations out of poverty. Many people in such areas have poor living standards, are affected by the risks brought by modern society, such as climate change and pandemics, and are unable to enjoy the benefits of modern institutions. Therefore, to solve the global food crisis, eliminate poverty, and reduce inequality across regions, regulating resource misallocation to drive domestic production is key, which will thus enhance returns in order to achieve the development of agriculture.
As a new industrial system and developmental stage of agriculture, modern agriculture’s ultimate purpose is to achieve a rough convergence of the return on investment in agriculture with that of other industries [4
]. Therefore, it is of great significance to undertake the following: (1) improve agricultural land systems, production, science, and technology; (2) realize the linkage between the agricultural sector and other sectors; (3) highly integrate the three industries of manufacturing, service, and agriculture; (4) establish a market-oriented agricultural commercialization and industrialization management model [5
]; and (5) improve the agricultural operators’ human capital level, thus enhancing the modern attributes of the input factors and reducing their transaction costs.
Road infrastructure is not only a necessary condition for social productivity and livelihoods but also the carrier of regional economic operation. Road infrastructure expands the market scope and realizes economies of scale and specialized production by reducing transaction costs in the spatial dimension, which in turn promotes competition and the diffusion of knowledge and technology [6
]. In developing countries, not only can the improvement of road infrastructure conditions increase the opportunities for the rural labor force to transfer to non-agricultural industries, but it also reduces the mismatch of social factors of production in various fields [8
]. Meanwhile, rural road facilities can reduce the spatial distance between farmers and the market, the time for agricultural products to reach markets, and transaction costs, such as labor and transportation. They can also motivate farmers to increase commodity inputs, promote specialized production, achieve economies of scale, promote the development of the non-agricultural sector in rural areas, thus increasing agricultural profitability, and play a central role in rural development [9
With the help of the regional road system, agricultural production is capable of positively interacting with other social production activities. A steady transfer of rural labor is created when the yield rate of non-agricultural work exceeds the yield rate of agriculture. In this process, on the one hand, urban production obtains the required labor capital and starts to expand and increase in value. On the other hand, in rural production, the labor input factors are replaced by other modern factors. Modern systems such as the market, property rights, and credit are popularized in rural areas. Social production factors are effectively allocated, and the regional economy grows. When there is a socio-economic crisis and the yield rate of non-agricultural work is lower than the yield rate of agriculture, a reasonably modern system contributes by providing convenience and support for the return of rural workers to ensure employment.
However, the ecosystem is an important constraint for both agricultural production and road infrastructure development. Agro-environment refers to the quantity and quality of agricultural land, water, and biological and climatic resources that support human survival and development [10
]. Thus, a good agro-ecological environment is a key component of sustainable rural socio-economic development, upon which agricultural production is highly dependent [11
]. While the transition to the modernization of agricultural production has increased the agricultural production efficiency, there is a risk of ecosystem neglect, leading to a series of agro-ecological problems, such as soil degradation, water eutrophication, soil erosion, fragmentation of agricultural landscapes, agricultural non-point source pollution, loss of ecological balance, and a reduction in species diversity. Although ecosystems have a certain self-healing capacity for external disturbances, i.e., socio-ecological resilience [13
], when the disturbance exceeds the resilience, the system will enter an unpredictable state, the result of which is often beyond human comprehension. In many developing countries, the deterioration of the agricultural eco-environment (AEE) is becoming increasingly prominent, leading to rural pollution, and is seriously threatening the sustainable development of food production and agriculture, thus further decreasing the livable land area for human beings.
Road facilities, as man-made landscapes superimposed on ecological landscapes, generally negatively impact ecosystems on three different levels: climate, species, and ecological landscapes. This is evidenced by the impacts such as air and water pollution, increased temperatures at road areas, changes in population densities, a reduction in species numbers or extinction of species, reduced biodiversity, and the fragmentation of natural habitats [14
]. Even though the benefits of road infrastructure are many, expanding this infrastructure type should be done with caution.
Previous studies have provided useful references for qualitative and quantitative studies related to the relationship between agricultural production, regional road construction, and the agro-ecological environment. It is necessary to build regional road systems for agricultural production under environmentally acceptable conditions to help developing countries improve their agricultural systems in a smooth manner. For most developing countries, rural areas are still the most important production and settlement areas [15
], and the food production issue is pressing. Previously some studies have been conducted on the interaction between the agro-environment, agricultural production, and road construction, however there is a lack of integrated approach that determine a successful interaction among three of them. In large part, this is due to the fact that the policies that focus on these three factors do not tend to occur simultaneously in more developed countries. Only developing countries are likely to make these fields a top priority within their national development strategies, hoping to achieve breakthroughs in these fields by taking advantage of the latecomers and catching up to the leaders. However, it is hard to hear such countries asking for help in the highly competitive international arena.
Agriculture plays a pivotal role in Cambodia’s national economy. Despite the constraints, such as lagging infrastructure and technology and lack of financial and human capital, Cambodia is rich with an ample labor force, great market potential, and substantial agricultural resources, such as rice, soybeans, corn, cassava, and cashew nuts. The Cambodian government has made agriculture a priority on their national development agenda, with approx. 85% of the population engaged in agriculture across approx. 6.7 million hectares of arable land in the country. The exports of agricultural products account for a large proportion of the total export value, and the government has made every effort to improve agricultural production and its investment environment. As a lower middle-income country, Cambodia is an ideal example of the interaction between agricultural production, regional road construction, and the agricultural eco-environment. With a relatively stable political society, open policies, and rich natural resources, Cambodia is one of the most attractive destinations for investment among the ten countries that have joined the Association of Southeast Asian Nations (ASEAN). However, although financing for infrastructure development takes up a considerable share of investment, the current transportation infrastructure development is unable to meet the country’s economic development needs [16
]. Currently, Cambodia is promoting the “Rectangular Strategy”, focusing on the renewal and reconstruction of its infrastructure. What’s more, according to the different levels of local and regional development in Cambodia, it is possible to yield twice the result with half the effort by rationalizing the industrial policies and utilizing resources efficiently.
As a result, given the above considerations, this study comprehensively evaluates the level of agricultural production, regional road construction, and the agricultural eco-environment in Cambodia in 2019. It then explores the interaction between agricultural production, regional road construction, and the agricultural eco-environment using the coupling coordination model, and finally analyzes the impact of regional road construction and the agricultural eco-environment on agricultural production using the gray correlation model.
4. Results Analysis
4.1. Spatial Pattern of Agricultural Production, Road Construction, and the Agricultural Eco-Environment
Agricultural development in Cambodia is still dominated by self-sufficient smallholders. This is due to a lack of roads and other associated infrastructures. Agricultural technology is underdeveloped, and farmland is highly fragmented and extensive. The overall domestic evaluation of agricultural production (AP) in Cambodia was significantly lower than that of the agro-ecological environment (AEE) and higher than that of road infrastructure (RE), as shown in Table 5
. The composite level of the comprehensive evaluation of Cambodian agricultural production was low, and there was no spatial autocorrelation. The first grade of the comprehensive evaluation is Oddar Meanchey, upstream of Tonle Sap Lake; Kampong Thom, downstream; and Stung Treng, in the highland mountainous area. However, the Tonle Sap Lake area and the southern plain with superior natural conditions have yet to be well developed.
There was a fault-like gap in Cambodia’s road system. Road construction in the vast majority of areas was at an extremely low level. Only in the bordering areas of the plains near other countries, such as the capital city, and the coastal cities with good locations, were well built to some extent. In Phnom Penh, the road length per square kilometer was 980 m, and in Koh Kong it was 42 m per square kilometer. When conducting this research, we drove at a constant speed of 100 km/h at an intersection in Phnom Penh, the average time for us to reach the next intersection was 1.9 h. A trip like this in Koh Kong takes 4 h. Systematic road construction is often closely related to regional development. The road system showed significant spatial autocorrelation, almost forming a low-value agglomeration zone at the downstream vertical line of Tonle Sap Lake. Apart from that, Svay Rieng, as one of the important areas for Cambodia’s cross-border communication, was also at the low-value aggregation.
In addition, the overall agricultural eco-environment performed well. As shown in Figure 3
, the coastal areas and the eastern plateau and mountainous areas ranked higher, while the Tonle Sap Lake area and the plain areas ranked lower. Significant spatial autocorrelation, as shown in Table 5
, formed an agglomeration of low values in the plains areas around the capital Phnom Penh and high values in Ratanakiri, as shown in Figure 4
4.2. Analysis on the Coupling Characteristics of Agricultural Productio, Road Construction, and the Agricultural Eco-Environment
The overall coupling coordination degree (D) of Cambodia was at the low coordination stage (0.4–0.6), as shown in Table 5
. Among the 25 subordinate provinces and municipalities, 18 provinces and municipalities were in the low coordination stage, accounting for 72%, while four provinces and municipalities were in the basic coordination stage (0.6–0.8), accounting for 16%, as shown in Figure 5
The main reason for the low coupling was the low comprehensive level of the integration (T) of agricultural production, road construction, and the agro-environment in Cambodia. What’s more, in terms of the coupling level (C), the mean value was 0.7952, which indicated that there was a certain interaction between the systems. Among them, there were 20 areas with a high coupling level of grinding and above, and 17 areas with a high coupling level (0.8–1.0), accounting for 68% of the total number of areas. However, as for the comprehensive level, the average was only 0.3533. The only areas with comprehensive levels higher than 0.5 were Kampong Thom, Pailin, and Oddar Meanchey in Tonle Sap; Mondulkiri and Stung Treng in the highland mountainous area; and the capital Phnom Penh.
In terms of agricultural production, the agricultural eco-environment near the capital Phnom Penh and in the Tonle Sap Lake area of Kampong Thom, Banteay Meanchey, and Oddar Meanchey exceeded the limit of what it can bear. Thus, enhancing local agricultural production is imperative. Meanwhile, there is potential for further advanced development of the agricultural production system in the Tonle Sap Lake area and the highland mountainous areas in the east and west, but it ought to be done according to each area’s unique geographical context.
As for road construction, most of the road systems in Cambodia do not have an overly negative effect on the local ecosystem. Nevertheless, in areas with a high level of economic development (Phnom Penh, Pema, Svay Rieng), roads do pose environmental risks, such as land erosion and a reduction in species diversity that could possibly lead to crises, as shown in Figure 6
. What’s more, lagging road development mostly occurred in Tonle Sap Lake where the highland mountains are suitable for agricultural production and where the overall assessment of agricultural production is relatively high for Cambodia. Even the road systems created by economic exchanges with other countries are unable to meet the requirements of local agricultural production. As a result, the economic value of agricultural products is not fully utilized [40
]. At the same time, the development potential that roads should bring to areas with higher economic development is not fully realized, and there is a need and an opportunity to transfer the rural labor force to other labor-intensive industries, such as light manufacturing, to help these industries develop.
To sum up, as shown in Table 6
, Cambodia has the following problems in the fields of agricultural production, road environment and the agro-environment: (1) potential environmental risks in the Tonle Sap Lake area and the plain areas. (2) Environmental risks of roads and the need for rural labor transfers in areas with a high level of economic development. (3) Lagging road construction in most of the main agricultural production areas. (4) Great potential but limited level of agricultural production development and utilization in some areas.
4.3. Analysis of the Interaction among Agricultural Production, Road Construction, and the Agricultural Eco-Environment
In order to adequately explore the current problems in Cambodia, the interaction between agriculture, roads, and the agricultural eco-environment was analyzed using the gray association model. Generally, a light association was considered when 0 <
≤ 0.30, a moderate association when 0.30 <
≤ 0.60, and a strong association when 0.60 <
≤ 1.0 [41
Regarding the input of agricultural production, the contribution of roads for improving the quality of agricultural labor is all-encompassing, as shown in Table 7
. Currently, the density of the road network in Cambodia has the greatest impact on physical labor, the intellectual input of the labor force, and the percentage of the rural population engaged in agriculture. Road accessibility has the greatest influence on the share of the agricultural population in the greater population. With regard to the environment in Cambodia, the reduction in the agricultural population and the improvement of farmers’ morality and behavior will lead to a greater stabilization of the ecological environment [42
]. Apart from that, fertilizers compensate for the efficiency lost due to the agricultural population shift and increase the efficiency of agricultural production [44
], thus decreasing the agricultural labor time. Meanwhile, the education level of agricultural laborers could improve fertilizer utilization and reduce disturbances to the ecosystem. On the other hand, the increased rural population puts pressure on agricultural households. The increase in the population engaged in agricultural production increases the multiple cropping index and improves the utilization of arable land while contributing to an increase in the fragmentation index. In addition, the physical input of labor has the potential to increase the multiple cropping index while reducing the structural stability of the ecosystem.
On the output side, the increase in per capita production value requires several aspects: the moderate use of fertilizers, an improvement in the multiple cropping index, a reduction in rising production costs caused by landscape fragmentation [45
], and the improvement of road accessibility to expand the market range, as shown in Table 8
. To increase the proportion of harvested agricultural products, on the one hand, a stable ecosystem is needed to reduce the loss of agricultural crops due to extreme weather. On the other hand, in terms of agricultural products, expanding their market demand via road transport, achieving their cross-regional transportation, and improving their commercialization are all necessary steps. The commercialization of agricultural products is closely related to both the road system and the agricultural eco-environment, with accessibility and fertilizer use per unit area being the most influential factors, respectively.
In general, as a predominantly agricultural economy, Cambodia’s output side of agricultural production accounts for a relatively high proportion of agricultural production, as shown in Table 9
. Various measures must be taken to improve the agricultural production capacity or increase the output. These include maintaining a per capita arable land area, ensuring ecological stability, reducing regional fragmentation, rationalizing road nodes, and providing high-quality roads as much as possible based on the local context. Focusing on the factors such as road connectivity, road accessibility, and the arable land area per capita will help to fully utilize the labor force.
In addition, when evaluating the environmental risks of roads, the impact of road accessibility, grade level, connectivity, technology level, and other such attributes should be the key considerations, as shown in Table 10
The length of regional roads is the primary consideration in order to expand the agricultural product market and achieve an agricultural population transfer as well as more efficient agricultural production in the main agricultural production areas where the level and quality of roads are lagging. The scale of investment in road construction is large, the pay-off time is long, and sometimes even foreign teams are required to build and operate the roads. Therefore, it is also necessary to improve the length of regional roads while rationally taking into account road planning, road quality, and other factors to achieve efficient, low-budget, and long-term use of roads. Road connectivity is one of the priorities for road supply. However, for the agricultural production development in areas with potential, there are certain differences. In the coastal and highland mountainous areas in the northeast, the ecosystem is particularly sensitive to human disturbance. Thus, developing modern agriculture, improving agricultural production from the input side, and strengthening personnel exchanges with the surrounding areas is key. Apart from this, in the Tonle Sap Lake area, it is preferable to improve agricultural production from the supply side and make full use of the local land resources to achieve solid agricultural development. For some areas, to address the potential environmental risks in agricultural production, the customs and behavior of the local residents should be emphasized to minimize disturbances to the ecosystem and improve its stability. Additionally, laws should be formulated in conjunction with publicity initiatives to mitigate agricultural landscape fragmentation.
High economically developed areas have road environmental risks. A reasonable assessment based on the attributes of the roads should be conducted, as well as a subsequent hedging of environmental risks and corresponding ex-ante crisis management. A cautious attitude in road planning and a research-based selection of road nodes and grades is also needed. In addition, connections with neighboring areas should be strengthened to enhance the ease of public mobility. Though there are still some areas with sound coordinated development, their overall level of development is not high. Therefore, further related work should be carried out, particularly taking the local context into account.