Comparison of the sustainability of bean production systems based on emergy and economic analyses.

To address increasing demand, bean producers have intensified agricultural activities by increasing application of industrial inputs. Such intensification can impose environmental risks to vulnerable ecosystems. Emergy and economic analyses were utilized in this study to investigate and compare the environmental performance of five management patterns specified by differing degrees of intensification, i.e., ecologic, integrated, low-, medium-, and high-input production systems at Bean Research Station in Khorram Dasht, Iran. The total emergy supporting these systems was estimated to be 6.52E + 15, 1.22E + 16, 6.62E + 15, 1.10E + 16, and 1.54E + 16 sej ha-1 for the ecologic, integrated, low-, medium-, and high-input systems, respectively. The purchased emergy inputs accounted for the largest portion of the total emergy inputs to these systems and ranged between 60.84 and 75.80%. The renewable fractions, transformities, emergy yield ratios, environmental loading ratios, emergy sustainability indices, and the economic output to input ratios demonstrate that the ecologic and low-input systems performed well compared to the three more industrial systems when considering their environmental sustainability. However, the more industrial systems had comparatively higher economic output. Generally, the results illustrate that sustainable bean production will depend on the transition from fossil fuel-intensive systems to more natural resource-intensive ones. To achieve more sustainable systems, applying conservation tillage and replacing chemical fertilizer with organic fertilizer are advocated for use in bean production systems. Joint use of emergy and economic evaluation provided different but complementary standpoints for comparison of the five bean production systems examined, and can assist in solving the problems that may occur in decision-making.