Document Type : Research Article
Department of Agronomy, College of Agriculture, University of Zabol, Zabol, Iran.
Sustainability analysis of agricultural ecosystems is important in their decision-making and proper management. Quantifying the sustainability of cropping agroecosystems can provide solutions to achieve positive economic and environmental results. Emergy analysis can be used to determine the degree to which ecological and economic systems are sustainable. By employing this method, we can gain a better understanding of ecological and economic systems and their interactions. Emergy analysis quantifies both environmental and economic costs associated with achieving sustainability, allowing for integrated management of ecological and economic factors. Emergy analysis is currently being used in agriculture to determine the sustainability of various scales of production systems. The present study was conducted to monitor the sustainability and productivity of the use of inputs in wheat, barley and alfalfa production systems using emergetic indicators, using information collected from the smallholder in Boland village, Sistan, Iran during 2019.
Materials and Methods
Boland village is located in Teymurabad village, approximately 17 kilometers north of Zabol city in Sistan and Baluchestan province. Boland village's agricultural composition includes wheat, barley, and alfalfa cultivation. 148.9 hectares were designated for wheat cultivation, 50.8 hectares for barley cultivation, and 13.5 hectares for alfalfa cultivation during the study year. The inputs used included environmental renewable and non-renewable resources as well as purchased resources. These data were gathered during the study period using a database of agricultural organizations, verbal estimates, field measurements, and researcher observations. The first step is to analyze the system's boundaries and draw an energy diagram to classify the system's inputs. Emergy analysis's second step is to create emergy evaluation tables. After quantifying each system's input flow in joules, grams, or Rials, the inputs were multiplied by their transformities to obtain the solar emjoule (sej). Specific emergy, unit emergy value, renewable emergy percentage, emergy investment ratio, emergy yield ratio, environmental loading ratio, environmental sustainability index, and emergy exchange ratio were all used in this study.
Results and Discussion
Free renewable and non-renewable flows accounted for 50.79%, 45.89% and 42.29% of the total input current of wheat, barley and alfalfa production systems, respectively. The large share of free domestic inputs indicates that the majority of study farms are non-industrial systems that are managed in a semi-traditional, low-input manner. The emergy input of non-renewable environmental resources was 2.73E+17, 6.42E+17, and 4.99E+17 sej/ha in wheat, barley, and alfalfa systems, respectively. Wheat and barley production systems have high emergy flows due to the high loss of soil organic matter and soil erosion in these systems. In wheat, barley, and alfalfa production systems, the highest proportions of purchased exergy resources were associated with animal manure, nitrogen fertilizer, and phosphorus fertilizer, respectively. In wheat, barley, and alfalfa production systems, the unit emergy value was 4.44E+05, 3.80E+05, and 3.64E+05 sej/J, respectively. The higher exergy efficiency of alfalfa production systems compared to wheat and barley production systems may be attributed to alfalfa's comparable economic performance to other systems. EYR was calculated to be 2.03, 1.85, and 1.73 in wheat, barley, and alfalfa production systems, respectively. The reason for the higher EYR in wheat production is that less purchased resources are used and a greater proportion of inputs are provided by purchased resources. Additionally, the ELR values for wheat, barley, and alfalfa production systems in Boland village were 17.36, 16.09, and 7.08, respectively.
The calculated values for emergy sustainability indices (ESI and ESI*) showed that the ecological sustainability of the alfalfa production system is higher than other study systems. The main reason for the greater sustainability of this system was the large share of input energy related to free environmental inputs and economic renewable resources. Also, low energy exchangeable ratio (EER), environmental sustainability resulting from market impact, less emergy expended in the production of each output unit and higher productivity of total production factors indicate a greater comparative advantage of the alfalfa production system.
In general, the evaluations based on the calculation of emergy-based indicators showed that in the dominant agricultural systems of the Boland village, Sistan, attention to practical solutions in the comprehensive management of the production system, especially protection of soil organic matter and prevention of soil erosion, can have a significant impact on ecological sustainability.