Production efficiency and GHG emissions reduction potential evaluation in the crop production system based on emergy synthesis and nonseparable undesirable output DEA: A case study in Zhejiang Province, China.

Paul C Struik,Gang Dong,Xianqiang Mao,Zhengzao Wang

doi:10.1371/journal.pone.0206680

Paul C Struik, Gang Dong + Show 2 more

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https://doi.org/10.1371/journal.pone.0206680

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Abstract

Maintaining crop outputs to feed its large population with limited resources while simultaneously mitigating carbon emissions are great challenges for China. Improving the efficiency of resource use in crop production is important in reducing carbon emissions. This paper constructs a methodological framework combining emergy-based indicator accounting and a nonseparable undesirable output slack-based measurement (SBM) data envelopment analysis (DEA) model. This framework is used to explore the efficiency of inputs and outputs and the greenhouse gas (GHG) emissions reduction potential for crop production systems, using Zhejiang province, China, as a case study. It is found that an emergy synthesis and a nonseparable undesirable output SBM-DEA framework is compatible with the case study. Crop production in Zhejiang province has relied heavily on an increase in agrochemical inputs to maintain agricultural output. Energy and chemical fertilizer use are determined as the province’s major carbon emissions sources. Although carbon emissions per unit of monetary output has decreased sharply, the carbon emissions per unit emergy output has increased, demonstrating a high carbon intensity reality. The DEA highlighted the differences in crop production efficiency, resource factor redundancy and carbon mitigation potential in the different prefectures of the province. To conclude this research, policies to support low carbon agriculture development, including subsidizing low carbon agriculture technology development and expansion and the cancellation of subsidies to high carbon production factors, such as chemical fertilizer production and sales, are discussed to conclude the research.

Highlights

The agricultural sector accounts for almost 14% of global net carbon emissions [1]
In China, agricultural production accounted for 11% of total carbon emissions, over 70% of total nitrous oxide (N2O) emissions and approximately 50% of methane (CH4) emissions in 2005 [4]
Production efficiency evaluations based on energy or emergy accounting and classifying direct and embodied carbon or greenhouse gas (GHG) emissions as nonseparable undesirable outputs have become essential elements in the evaluation of the sustainability of agriculture practices; these evaluations may generate important implications for decision makers

Summary

Introduction

The agricultural sector accounts for almost 14% of global net carbon emissions [1]. In China, rapid industrialization, urbanization and land-use changes have led to a reduction in cultivated land across China over the past few decades [2]. To increase crop productivity and sustain its large population, the conventional approach in China is to intensively apply high carbon inputs, such as fertilizer, agricultural machinery, fuels and other industrial products. This heavy reliance on high carbon inputs has caused large direct and indirect greenhouse gas (GHG) emissions in the agricultural sector [3]. Production efficiency evaluations based on energy or emergy accounting and classifying direct and embodied carbon or GHG emissions as nonseparable undesirable outputs have become essential elements in the evaluation of the sustainability of agriculture practices; these evaluations may generate important implications for decision makers

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