Conservation agriculture, a selective model based on emergy analysis for sustainable production of shallot as a medicinal-industrial plant

Abstract

In addition to achieving of food security in the long-run, the identification and introduction of sustainable ecosystems is associated with the protection of natural resources and the provision of environmental services that flow from those resources. A paradigm for the production of shallots has arisen in the agroecosystems of Iran to prevent the extinction of the shallot plant, on one hand, and to meet the market demand for this valuable medicinal-industrial product, on the other. This study aimed to identify the most sustainable shallot production system by comparing mechanized, traditional, and conservation shallot production systems with the growth of this plant in its natural habitat in Selseleh County, Iran, during 2018–2019. The analysis was done by calculating net emergy of each system and by reviewing 14 different emergy indices. Soil conservation is very important in the sustainability of agroecosystems. In this regard, a positive evaluation of the energy input structures in a conservation system is based on the soil stability of that system. The results showed that the status of a protected system is optimal based on the values of the Unit Emergy Value (UEV = 6.62E+05 sej J −1 ), Specific emergy (SE = 7.05E+09 sej g −1 ), Inverse emergy exchange ratio (IEER = 0.942), and Emergy index of product safety (EIPS = 1) indices and, to some extent, on Renewable emergy ratio (R%), Modified version of the environmental sustainability index (ESI∗), Modified version of the environmental loading ratio (ELR∗), and Emergy invested per $ net profit (EINPR). As a result, the most optimal system was found by increasing the amount of the free environmental renewable input flow (R). The optimal EINPR, Economic emergy efficiency (EEE) and IEER values of the natural habitat indicate the risk of overharvesting shallots from this system, which necessitates paying more attention to protecting the ecosystem and preventing overharvesting. Although a number of indices showed the advantage of the mechanized shallot production system over the other two agroecosystems. However, since an important part of the desirability of a mode of production implied by these indices is related to the share of free environmental inputs that are used in a renewable manner, modes of production that rely heavily on the non-renewable use of free environmental flows and result in soil instability are not preferred, thus a mechanized system is not recommended as the first choice for shallot production. The equality of the EIPS index both in conservation and in natural systems showed the high quality of the crop in the conservation system among the studied crop systems.