Emergy analysis for sustainability assessment of potato agroecosystems (case study: Golestan province, Iran)

Intensification in cropping systems with limited natural resources has necessitated the determination of agroecosystem sustainability in terms of both economic and environmental aspects. Emergy analysis is adopted to determine the most important indicators related to efficiency, renewability, environmental pressure, and sustainability of potato agroecosystems. The present study was carried out in 2018 using monitoring, questionnaires, and in-person interview with 120 farm managers and farmers in the autumn potato agroecosystems of Golestan province, located in northeastern Iran. The emergy indices were calculated following the determination of different inputs and outputs of the agroecosystems. The spatial distribution of emergy indices was analyzed in geographic information systems (GIS) environment. For this purpose, GIS-emergy tools were defined by different geostatistical and classic interpolation methods. The results revealed that total emergy input was 1.71E + 16 seJ ha(-1) yr(-1) for supporting the potato production system. Among all inputs, groundwater had the highest share because of the high water requirement of the potato crop and surface irrigation in most agroecosystems. Based on the data from the surveyed fields, over two-thirds of the total emergy input was related to the purchased resources, which indicated that potato production systems were extremely open systems and influenced by the market. Furthermore, transformity and specific emergy were 1.50E + 05 seJ J(-1) and 5.41E + 08 seJ gr(-1), respectively, which points to the efficiency of autumn potato production systems. Renewability in this research was almost 22.85%, which indicates the heavy dependence of this production system on non-renewable resources. In potato agroecosystem, emergy yield ratio was equal to 1.44, emergy investment ratio was calculated as 2.29, standard environmental loading ratio was equal to 29.10, modified environmental loading ratio was obtained as 3.38, standard emergy sustainability index was found to be 0.05, and modified emergy sustainability index was equal to 0.57. The emergy indicators attributed to the environment shed light on how this production system exerts extensive environmental impact and is a depleting producing system that needs to use a large amount of energy. In final, acceptance of more sustainable techniques, especially new irrigation systems, conservation tillage methods, and use of suitable potato seeds, may reduce the environmental loading and increase the sustainability of the potato agroecosystems in Golestan province.