Evaluation of sustainability of rainfed rapeseed production in Gorgan county using Emergy analysis

Excessive use of environmental resources and excessive consumption of chemicals have exacerbated environmental problems and harmed agroecosystem sustainability. As a result, it is beneficial to study energy consumption patterns and efficient energy use in agriculture, which is one of the fundamental principles of sustainable agriculture. The aim of this study was to assess the sustainability of rapeseed production (Brassica napus L.) in Gorgan county during the 2017-2018 crop year using emergy essessment. Sixty questionnaires were considered for this purpose. After establishing spatial and temporal boundaries and classifying resources into four categories: renewable environment, non-renewable environment, purchased renewable, and purchased non-renewable, and some emergy indices were calculated in rapeseed agroecosystems. The results indicated that the total emergy input for the rapeseed agroecosystems consumed a total of 6.39E+15 sej ha-1 yr-1. In rapeseed agroecosystems, dependence on market and non-renewable inputs was much higher than environmental and renewable inputs. With 59.94 percent of total emergy input in rapeseed agroecosystems, fossil fuels were the primary source of emergy. The transformity of rapeseed agroecosystems was 1.09E+05 sej J-1, the specific emergy was 3.09E+09 sej gr-1, the renewability was 12.46 percent, the emergy yield ratio was 1.22, the standard emergy investment ratio was 4.56, the modified emergy investment ratio was 9.23, the standard environmental loading ratio was 10.25, the modified environmental loading ratio was 7.02, the standard emergy sustainability index was 0.12, and the modified emergy sustainability index was 0.17. Based on the evaluation of emergy indices, the rapeseed agroecosystem has an acceptable crop production efficiency and resource consumption efficiency, and a significant potential for economic productivity increase. By implementing conservation tillage and modernizing machinery, will reduce our reliance on non-renewable and economic inputs, alleviate environmental pressure, and increase the agroecosystem's sustainability.