Elsevier

Ecological Indicators

Volume 107, December 2019, 105650
Ecological Indicators

Original Articles
Comprehensive evaluation and optimization of agricultural system: An emergy approach

https://doi.org/10.1016/j.ecolind.2019.105650Get rights and content

Highlights

  • Comprehensive methodology of emergy accounting and optimization is established.

  • Sensitivity analysis and “3R” principle is applied for optimization of emergy system.

  • Optimization design can contribute to the agriculture sustainable development.

Abstract

China’s agriculture is facing a series of severe challenges such as increasingly tight resource constraints and deteriorating environmental problems. The intensive utilization of agricultural resources and sustainable development of agricultural have been paid more and more attention by the Chinese government. Hence, an emergy approach is employed in this study to comprehensively evaluate economic benefit, environmental pressure and sustainability performance of agricultural system in Gaomi city. The results showed that the emergy yield ratio (EYR), the environmental loading ratio (ELR) and the emergy sustainable index (ESI) of the agricultural system are 2.25, 1.91 and 1.18 respectively. To further improve the sustainable development level of the agricultural system, the sensitivity analysis is used to identify key emergy flows restricting its sustainable development. On this basis, tracing the source to find the key substances. Finally, according to the position of key substances in the agricultural system, the Reduce-Reuse-Recycle (“3R”) principle of circular economy is introduced to design three optimization scenarios. The results showed that if all the three optimization scenarios proposed in this study are realized, the sustainable development level of the agricultural system in Gaomi city can be increased by 52.51%. The emergy optimization methodology system based on “3R” principle proposed in this study can provide a new perspective of an industry evaluation.

Introduction

Global challenges including food security, population explosion and environmental pressures require widespread actions to develop global sustainable agriculture (Foley et al., 2011, Tilman et al., 2011). As one of the largest agricultural countries in the world, the stable development of China’s agriculture is of great significance to the sustainable and healthy development of its economy and society. However, with the rapid development of economy and the acceleration of urbanization, China's agriculture is facing a series of severe challenges. On the one hand, the constraints on agricultural resources are becoming increasingly tight (Tao et al., 2008). On the other hand, the issue of agricultural environment is becoming increasingly prominent. For example, the area of cultivated land is decreasing (Cohen et al., 2006), the soil erosion is serious (Lu et al., 2015), and the river ecosystem is influenced (Kuriqi et al., 2017, Kuriqi and Ardiçlioǧlu, 2018, Kuriqi et al., 2019). The increasingly serious resource and environmental problems force people to rethink the development mode of Chinese agriculture. China’s 13th Five-Year Agricultural Development Plan clearly states that it is necessary to gradually improve the science and technology system that requires high-efficiency, resource-saving and environmentally-friendly agricultural development. Promoting a typical agricultural production model that can be replicated and can be used for reference is one of the important tasks that the Chinese government must do. Therefore, how to effectively evaluate China's existing typical agricultural production model? How to identify the key elements that constrain its sustainable development based on effective evaluation? How to propose ideas and feasible methods for optimizing design based on the identification of key elements? The solution of these above problems has a good practical and strategic significance for demonstrating the role of typical agricultural production models and improving the sustainable development of China’s agriculture.

An agricultural system is very suitable for the application of the emergy approach, because this method is particularly appropriate for evaluating systems at the interface between “natural” and “human” spheres (Castellini et al., 2006). Therefore, the emergy accounting method has been widely applied to evaluate the sustainability of agricultural systems. Tao et al. (2013) analyzed the crop production system in the 31 provinces of mainland China by using emergy accounting method and divided the 31 provinces into 10 groups by cluster analysis. Jaklič et al. (2014) applied emergy theory to evaluate nine agricultural types and found that organic farms were more capable of utilizing local natural resources. Ferraro and Benzi (2015) assessed the long-term trends of the three cropping systems in Pampa region (Argentina) from 1984 to 2010. It is shown that the region had higher emergy yield ratio (EYR) and lower environmental loading rate (ELR). Zhang et al. (2016) adopted emergy analysis to assess the sustainability of Chinese crop production system during 2000–2010. The results showed that the sustainability of China's crop production system is reduced by 37.01% during this study period. Jafari et al. (2018) indicated that date production is the better system to achieve long-term sustainable development in comparison with pistachio production by using emergy theory. Ali et al. (2019) investigated the drivers and consequences of changes in crop production sustainability in India and Pakistan from 2001 to 2011 based on emergy.

With the gradual deepening of research, some scholars have tried to put forward some optimization suggestions and measures on the basis of agricultural emergy evaluation. Through the emergy analysis results, Ghisellini et al. (2014) found that land use change and labor productivity are important factors that restrict the sustainable development of Italian agriculture. Houshyar et al. (2017) analysed different scenarios indicated that unit emergy value and all the sustainability ratios of the systems can be enhanced by around 20–55% via using appropriate water, nutrient, and agronomic management measures. Patrizi et al. (2017) confirmed that the integrated system (combined with the goose rearing subsystem and organic grape planting subsystem) could reduce emergy input by 33% compared to the two originating isolated production systems. Wang et al. (2017) evaluated the sustainability of recycling in agricultural systems by emergy accounting. Their research results indicated that recycling wasted biomass as organic fertilizer has been an important road to develop sustainable agriculture. Through quantitative analysis of renewable, non-renewable and purchase input, Ghaley et al. (2018) found that the sustainable production of fodder maize in Denmark can be optimized by reducing the use of machinery and diesel. Liu et al. (2019) applied a logarithmic Mean Divisia Index (LMDI) decomposition method to identify the key driving forces that affect the evolution of emergy sustainability index (ESI). The decomposition analysis results indicate that labor and renewable resources are the major factors affecting China's sustainable crop production.

Based on the above analysis, the existing agricultural emergy studies mainly focus on evaluating the sustainability of agricultural system. Although some studies have put forward some optimization design ideas on the basis of emergy evaluation, they have not formed a relatively complete emergy optimization methodology system. To fill this gap, the emergy optimization methodology system based on Reduce-Reuse-Recycle (“3R”) principle is proposed in this study. Namely, on the basis of emergy evaluation, the key emergy flows restricting the sustainable development of the system are identified through sensitivity analysis. Then, tracing the source to find the key substances. Finally, according to the position of key substances in system, the optimization scenarios are designed based on the ideals of “source reducing, process reusing, and end recycling”. The emergy optimization methodology system based on “3R” principle proposed in this study can provide a new perspective of an industry evaluation.

Section snippets

Study site

As a developing country with the world’s largest population, agriculture plays a fundamental role in the Chinese society. The country’s agricultural issue such as food security has long been a focus for international organization, policy makers, researchers, and other groups around the world (Fukase and Martin, 2016). In China, problems regarding land use change and sustainable development of agricultural production are particularly acute in Shandong, which is the third largest agricultural

Emergy evaluation of the agricultural system

Based on the research results of the unit emergy value (UEV), such as Yang and Chen (2014) and Odum (2000) etc., the UEV of each item in this study is preliminary determined. Then, according to the research on emergy baseline by Brown et al. (2016), 12E+24 sej/year is used as the latest emergy baseline, the UEV of each item under different baselines is determined. Emergy analysis table for the agricultural system are shown in Table 2. Emergy evaluation indicator system of the agricultural

Discussion

According to the position of key substances in the agricultural system, three optimization scenarios are designed based on the ideals of “source reducing, process reusing, and end recycling”.

Scenario 1: At present, the agricultural irrigation in this area is mostly single-family flood irrigation. This irrigation method not only causes water wastage, but also requires much power from machine and consumes a lot of energy. Due to the wide area of crops and the concentration of species, based on

Conclusion

A novel approach based on “3R” principle is proposed in this study for the optimization design of agriculture system. Namely, on the basis of emergy evaluation, the key emergy flows restricting the sustainable development of the system are identified through sensitivity analysis. Then, tracing the source to find the key substances. Finally, according to the position of key substances in system, the optimization scenarios are designed based on the ideals of “source reducing, process reusing, and

Acknowledgements

This research is supported by National Key R&D Plan (2016YFC0502805), China Major Science and Technology Program for Water Pollution Control and Treatment (2017ZX07101003), National Natural Science Foundation (41301640), Key R&D Plan of Shandong Province (2018GSF121005), Shandong Natural Science Foundation (ZR2019MG009, ZR2019MEE104), and the Fundamental Research Funds of Shandong University (2018JC049, 2018GN046).

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