عنوان مقاله [English]
Agricultural intensification has had negative effects on the environment. The sustainability in the agricultural systems that provides sufficient food on the one hand and maintains the quality of the environment on the other hand, is very important. In assessing the sustainability of agricultural systems, the contribution of both environmental and economic resources must be taken into account. Emergy analysis has many indices in which the efficiency, renewability, environmental burden, and sustainability of a system can be assessed in terms of environmental and economic. The purpose of this study was to evaluate and compare the resource use efficiency and sustainability indices for two autumn and spring potato systems and provide suggestions for optimum and sustainable management of the crop.
Materials and Methods
In this study, two production systems of potato were evaluated using emergy sustainability indices in Gorgan County, Iran during the period of 2017-2018. To this end, 100 and 60 farms were selected for autumn and spring potato, respectively. To analyze the production systems, the spatial and temporal boundaries of the system were defined and resources were divided into four categories: renewable environmental sources (R), nonrenewable environmental resources (N0), purchased renewable resources (FR), purchased nonrenewable resources (FN). Emergy flow for each item was multiplied by their transformities in joules and grams. In this study, emergy indices were calculated and compared by t-test between warm and cool production systems.
Results and Discussion
Total emergy inputs for the autumn and spring potato production were estimated as 1.71E+16 and 1.76E+16 sej ha-1 year-1, respectively. In autumn potato production, dependence on purchased inputs was higher than environmental inputs, while in spring potato production, the dependence of environmental inputs was higher than purchased inputs. Groundwater emergy was the largest emergy inputs of the total in both autumn and spring potato production systems with a share of 23.92% and 45.28%, respectively. In autumn and spring potato production system, transformities were 1.50E+05 and 2.54E+05 sej j-1; emergy renewabilities were 22.85% and 12.78%; emergy yield ratios were 1.44 and 2.06; emergy investment ratios were 2.29 and 0.94; environmental loading ratios were 29.10 and 30.02; and emergy sustainability indices were 0.05 and 0.07, respectively. There is a significant difference between the emergy indices of the autumn and spring potato production systems. Despite the higher contribution of environmental resources in the spring potato production system, the high consumption of groundwater as a non-renewable input led to an increase in environmental burden. The use of new irrigation methods will improve water consumption and, as a result, reduce environmental pressure on ecosystems. The autumn production system was more favorable in terms of yield and resources use efficiency, renewability and environmental sustainability than the spring production system. The economic sustainability of the autumn potato production system was slightly lower than that of the spring potato production system, largely due to the unreasonable use of purchased inputs such as seed and fossil fuels. Optimum management of inputs such as seed and fossil fuels will increase economic sustainability in the autumn potato production system. The optimization of economic inputs will increase economic sustainability in production systems (Kohkan et al., 2017).
Two autumn and spring potato production systems in Gorgan had significant differences in terms of resources use efficiency, input renewability, environmental burden and ecological sustainability. The autumn potato production system was more favorable in terms of resources use efficiency and environmental sustainability. The economic sustainability of the autumn potato production system was slightly lower than that of the spring potato production system. Optimizing inputs through the use of appropriate seeds (size and recommended amount), the use of soil tillage and modernization of machinery and diesel engines of the well will increase the economic sustainability of the autumn ecosystem.