A survey on the ecological sustainability of introducing new crops in the cropping pattern using emergy approach

The sustainability of production of four widely grown crops, including wheat and barley (as preceding crops in the cropping pattern) vs. sugar beet and saffron (as introduced crops in cropping pattern) were compared using emergy approach in Khoushab County, Khorasan Razavi province, Iran. The results showed that the total emergy consumption of the introduced crops was higher than that of preceding crops. The total supporting emergy for wheat, barley, sugar beet and saffron was respectively 2.32E+16, 1.91E+16, 4.95E+16, and 2.04E+16 sej ha−1. The greatest portion of renewable environmental resources were obtained in sugar beet production systems (4.1% of total emergy), and non-renewable environmental resources occurred in barley production systems (55.7% of total emergy). Saffron production systems showed the greatest portion of renewable purchased resources (40.8% of total emergy) and non-renewable purchased resources (36.48% of total emergy). Introduction of saffron and sugar beet as new crops in a given region, compared to wheat and barley as preceding crops in the cropping pattern, caused enhancement in renewable emergy ratio, environmental loading ratio, environmental sustainability index, and emergy input ratio, while decreased emergy yield ratio, environmental sustainability index, and sustainable development emergy index. Saffron and sugar beet production as new introduced crops to the region resulted in the highest environmental sustainability index. Although the environmental loading ratio index of saffron cultivation was higher than other production systems, modified environmental loading ratio was lower than the three other production systems. Therefore, saffron can be recommended as a sustainable crop that has put the lowest pressure on environmental resources. In this study, the results of emergy analysis and calculation of economic indicators, indicated the greater sustainability and economic benefit of the saffron production system compared to the other three systems. •The sustainability of production systems was increased by introducing new crops in cropping pattern.•Saffron, as a perennial plant, had more sustainability than annual plants.•Saffron production systems as a low-cost and high-income crops can be improved with more artificial input.•Reduced soil organic matter losses and increased organic fertilizer can improve sustainability of crop production in Khoshab.