عنوان مقاله [English]
The use of various inputs, such as pesticides and chemical fertilizers, has been one of the most significant factors negatively impacting the sustainability of agricultural systems. To accurately assess the value of agricultural ecosystem services, both the positive and negative aspects of agricultural systems must be taken into account. In the past three decades, the emergy analysis has been developed for assessing environmental policies and resource quality based on the dynamics of complex environmental and economic systems. Emergy analysis can be used to evaluate the sustainability of agriculture. By definition, emergy is the amount of direct or indirect solar energy required to produce a good or service. By converting all forms of energy, resources, and services into a single unit, the solar emjoule (sej), emergy analysis can assess the interdependence of economic, social, and environmental factors. The production of three important oil crops of Sistan, including rapeseed, safflower, and sesame, was investigated using emergy and economic analysis techniques to evaluate the ecological sustainability and productivity of the use of inputs in the production of oil crops in Sistan.
Materials and Methods
This research was conducted at the level of Sistan's oil plant production systems in the northern provinces of Sistan and Baluchistan. This research used questionnaires and face-to-face interviews with the owners of small ownership systems to determine the input consumption and performance of these systems. 56 rapeseed farmers, 33 safflower farmers, and 22 sesame farmers were chosen and investigated for this study.
According to their service life, the annual input energy flow in the form of structural facilities, buildings, machinery, and materials used in the systems was calculated. The RUSLE model was used to assess water erosion. Inputs are divided into four categories to analyze production systems: renewable environmental resources (R), non-renewable environmental resources (N), purchased renewable resources (FR), and purchased non-renewable resources (FN). After calculating all input and output flows, the raw data for each of the production systems was multiplied by their unit emergy value in Joules, grams, or Rials, according to Iran's conditions. This study utilized transformity, the renewable emergy ratio (R%), the rmergy yield ratio (EYR), the rmergy investment ratio (EIR), the rnvironmental loading ratio (ELR), the emergy sustainability index (ESI), the emergy exchange ratio (EER), and the emergy index of product safety (EIPS).
Results and Discussion
The total supporting emergy for rapeseed, safflower, and sesame production systems was calculated to be 7.28E+16, 4.75E+16, and 3.55E+16 sej ha-1 yr-1, respectively. In all three studied production systems, wind emergy was the largest source of free environmental input. In all three studied systems, environmental non-renewable inputs accounted for the largest portion of total emergy input, which was 83.42 percent for rapeseed, 80.11 percent for safflower, and 84.4 percent for sesame. The high proportion of nonrenewable inputs in this study for all three production systems demonstrates the vulnerability of Sistan's landscape cultivation systems as a result of the obvious lack of water, severe soil erosion, and contamination of agricultural lands. The total amount of purchased inputs for rapeseed, safflower, and sesame production systems was estimated to be 1.14E+16, 8.78E+15, and 5.40E+15 sej ha-1 yr-1, respectively. Nitrogen and phosphorus chemical fertilizers comprised the largest proportion of purchased inputs in all three systems.
The transformity for rapeseed, safflower, and sesame production systems, respectively, was 3.88E+06, 3.76E+06, and 2.48E+06 sej J-1. The higher transformability of the rapeseed production system was due to the lower input utilization efficiency of this system compared to the safflower and sesame systems. The values of the saffron system's environmental sustainability indices (ESI and ESI*), renewable energy ratio (%R), environmental loading ratios (ELR and ELR*), and modified investment ratio (EIR*) indicate that this system is more sustainable. The lower sustainability of rapeseed and sesame systems based on emergy indices was primarily due to the large proportion of input emergy related to organic matter losses and soil erosion, which are nonrenewable environmental resources. The economic analysis revealed that the sesame production system generated a higher profit-to-cost ratio and net profit than the safflower and rapeseed systems.