Sustainability assessment of autumn and spring potato production systems using extended exergy analysis (EEA)

摘要

The unreasonable use of inputs, including chemical fertilizers and pesticides, has put agricultural production at risk of unsustainability in many areas. Extended exergy analysis (EEA) is an innovative method for assessing the ecological sustainability of agricultural ecosystems. EEA allows for a comprehensive assessment of the material and immaterial flows in the system and, as a result, a more accurate assessment of sustainability. In this study, a comprehensive analysis of the sustainability of autumn and spring potato systems was performed based on the EEA approach in Golestan Province in Iran during the crop year of 2017-2018. for this purpose, 120 and 60 farms were taken into account for the autumn and spring farming systems, respectively. The extended exergy (EE) values of autumn and spring potato crops in Golestan Province were 2.30E + 05 and 1.68E + 05 MJ ha(-1), respectively. The highest shares of EE in both autumn (57.00%) and spring (48.64%) crops were related to cumulative exergy consumption (CExC). The excessive consumption of inputs in the autumn system led to enhanced CExC. The exergy of environmental remediation cost (EEE) for the spring farming system (7.84E + 04 MJ ha(-1)) was lower than that of the autumn farming system (9.20E + 04 MJ ha(-1)), which was mainly due to the high consumption of inputs like diesel fuel in the latter system. Accordingly, the ecological sustainability of the spring farming system was greater than that of the autumn farming system. The values of capital conversion factor (K-cap) for material and energy inputs to the autumn and spring farming systems were 0.011 and 0.014 US$ MJ(-1), respectively, which indicated that potato production in Golestan Province was more costly in the spring farming system. The values of the specific capital conversion factor of product sales (K-cap(EE)) for the autumn and spring potato systems were 0.006 and 0.005 US$ MJ(-1), respectively. Therefore, the economic efficiency of the autumn farming system was higher than that of the spring farming system. Also, the Extended Exergy Efficiency Indices (I](EE)) for the autumn and spring potato production systems were 45 and 37%, respectively, which represented the higher thermodynamic efficiency of the autumn farming system. The cumulative degrees of perfection for the autumn and spring potato systems were 0.78 and 0.77, respectively, which demonstrated the more optimal use of energy and materials in the autumn compared to the spring farming system. Based on the results obtained in this research, it is recommended to improve management models including selections of appropriate types and amounts of input consumptions corresponding to the systems so as to reduce costs and ameliorate thermodynamic-economic indices.