A sustainability analysis of two rapeseed farming ecosystems in Khorramabad, Iran, based on emergy and economic analyses

The overarching goal of this research was to provide sound strategies to further the development of rapeseed farming and to increase the sustainability and productivity of rapeseed production systems. Progress toward this goal was made by assessing subsistence and commercial rapeseed production systems in Khorramabad, Iran during the 2017-2018 crop year using both emergy and economic indices. The total emergy supporting the systems was estimated to be 4.13E+16 and 2.47E16+ sej ha(-1) yr(-1) for the commercial and subsistence rapeseed production systems, respectively. The calculated values of the modified environmental sustainability index, renewable emergy ratio, environmental loading ratio, and modified environmental loading ratio showed the higher ecological sustainability of the subsistence farming system compared to the commercial system for rapeseed production. According to these indices, the main reason for the lower sustainability of the commercial rapeseed production system was the large amount of soil organic matter that was lost per unit of nonrenewable resources used. A large emergy exchange ratio in favor of the buyer (EERYield); increased environmental sustainability, when the market impact is considered (Emergy Index of Sustainable Development, EISD); lower emergy required per unit of output (Unit Emergy Value, UEV) and the higher productivity of the production factors (Total Factor Productivity); all reflect the relative advantage of the commercial system over subsistence farming. Our findings revealed that the ecological sustainability of the commercial rapeseed production system can be improved by employing scientific solutions for comprehensive management of the ecosystem, especially through the amelioration of soil organic matter and prevention of its loss. Besides improving the farmers' technical knowledge, the integration of small lots into the overall production system is recommended for improving the economic sustainability of the subsistence farming systems. (C) 2019 Elsevier Ltd. All rights reserved.