جستجوی مقالات مرتبط با کلیدواژه « انرژی » در نشریات گروه « اکولوژی »

Wheat and maize are important and strategic crops in Iran. These crops are widely grown in the Dez catchment area. Therefore, due to climate change, recent droughts, water bankruptcy in the country, low water consumption efficiency in agriculture, and the excessive consumption of input which pose a serious threat to agriculture and food security, it is necessary to achieve a correct understanding of the sustainable production of crops in the region. Improper use of chemical fertilizers, pesticides, fossil fuels, machinery causes irreversible damage to the environment. To reduce these adverse environmental effects of methods the idea of sustainable agriculture and the transformation of agriculture from high-input to low-input consumption is very important. The footprint index determines the amount of pressure on nature caused by man or other man-made systems. The carbon uptake criterion is used as a basis for assessing the ecological footprint. Ecological footprint estimates the amount of productive land needed to compensate for the environmental impacts of a particular activity by calculating resource consumption and carbon dioxide production. According to studies, each hectare of land can absorb 1.8 tons of carbon. The carbon uptake criterion is used as a basis for assessing the ecological footprint.

The method of the present study has a practical approach because it is in line with achieving sustainable agricultural development. This research was carried out in the cropping year of 2019-2020 at the Dez catchment. To determine the environmental sustainability of agriculture we used the modified ecological footprint method presented by Kissinger and Gottlieb (2012) and Guzman et al (2013). In this study, the ecological footprint was determined based on a place-oriented approach by obtaining energy consumption of the inputs, and the amount of crop and land energy. All the variables were collected in the form of a questionnaire and through interviews with 400 farmers of wheat and maize in the study area. Equivalent factors were also selected from similar studies. Independent samples t-test was performed between the two crops to determine whether there are differences in evaluation of EF.

The results of evaluating the ecological footprint method of wheat and maize cultivation in the study area at the level of one hectare were 3.50 and 4.66 global hectares, respectively. The results of the ecological footprint assessment for wheat and maize showed that both cropping systems are in an unsustainable state in terms of the environment. These systems produce 1.7 tons and 2.86 tons of excess carbon to produce wheat and maize, respectively which are more than the ecological capacity of one hectare to absorb environmental pollution. For both wheat and maize crops, nitrate fertilizer with 40.85% and 49.36%, diesel fuel with 18.57% and 17.60%, and water consumption with 14.57% and 16.31%, respectively, had the greatest impact on environmental instability in the study area. Mean comparison of the ecological footprint between the two crops showed that there was no significant difference between wheat and maize. The high ecological footprint of traditional agriculture was consistent with previous studies (Naderi Mahdei et al, 2015; Kissinger and Gottlieb, 2012; Bevec et al, 2011). Also, the important role of nitrate fertilizer and fossil fuels in increasing environmental hazards and ecological unsustainability was consistent with Fallahpour et al, (2012). It should be noted that No study was found to contradict the findings of the current study.

Both wheat and maize cropping systems were not environmentally sustainable and the total consumption inputs for both crops; chemical fertilizers, especially nitrate fertilizer and then diesel fuel have had the greatest impact on environmental instability in the study area. As a final result, the ecosystem of irrigated wheat production is more desirable than grain maize in terms of environmental sustainability, therefore, the production of both crops, especially maize, must be done with the highest accuracy and consider environmental considerations in the region.

Water, food and energy are the main resources needed for the development of communities. The nexus view emphasizes the interconnected management of these resources and has been applied with a focus on three sources at the macro level. In this research, evaluation and prioritization of effective factors and methods of optimal resource allocation based on the nexus approach of water, energy and food production with the Analytic Hierarchy Process (AHP) in Alborz province has been considered. For this purpose, the criteria were compared in pairs in a hierarchical analysis with the opinions of experts and their importance was determined. Criteria including water, food and energy were considered. Factors affecting the optimal allocation of resources in Alborz province were determined and presented as multiple choice and compared in pairs based on questionnaires completed by experts. The results showed that the water criterion with the relative weight of 61.4% has the greatest impact on the evaluation process compared to other criteria and the energy and food criteria with the relative weight of 26.2% and 12.4% have the most impact, respectively. Among the developed strategies, education and awareness raising with a score of 35.9% was ranked first, and environmental policy with a score of 26.6% was ranked second. Therefore, it is suggested that strategies for education and promotion of awareness and environmental policy be given priority.

Tillage and irrigation methods may affect energy use and greenhouse gas (GHG) emissions in production process of agricultural products. Effect of tillage and irrigation methods on energy indices, GHG emissions, and GHG emissions intensity during irrigated wheat production in Fars province was evaluated in this research. 

This research was conducted in the form of a split plot experimental design with nine treatments and three replicates. Main plots were surface irrigation, tape drip irrigation, and sprinkler irrigation. No-till, reduced tillage, and conventional tillage were considered as sub plots.  Energy indices, GHG emissions, and GHG emissions intensity were determined. 

All energy indices were significantly affected by irrigation methods, but tillage methods only had significant effect on input and output energies. Tape drip and sprinkler irrigation reduced input energy compared to the surface irrigation by 30.5 and 14.8%, respectively, and tape drip irrigation had the highest energy productivity (0.214 kg.Mj-1). Conventional tillage had the highest input and output energies, while the minimum input and output energies were related to the no-till. Tape drip and sprinkler irrigation methods reduced the total GHG emissions compared to the surface irrigation (21.3 and 34.3%, respectively), but conservation tillage did not significantly decrease the total GHG emissions compared to the conventional tillage. Electricity for pumping irrigation water had the highest share in total energy use and GHG emissions. 

Therefore, using pressurized irrigation methods especially tape drip irrigation in wheat production process would significantly reduce energy use and GHG emissions.

Investigating the potential global warming, greenhouse gas emissions and energy flow is one of the methods for comparing the agricultural systems in terms of environmental hazards. This research examines the energy flow and greenhouse gas emissions (CO2, N2O and CH4) in rapeseed in North khorasan province of Iran.

This research was studied separately in three regions of East, West and South in North Khorasan Province. Energy input values of rapeseed fields were collected using a face-to-face questionnaire in the 2020-2019 crop years.

The results showed that the total input energy was 33.33178 MJ.ha-1 and the total output energy was 128545.05 MJ.ha-1. Energy use efficiency was 3.87 and energy productivity was 0.06 kg/MJ.ha-1. Direct and indirect input energies were 61.77% and 38.23%, respectively, and renewable energies was 11.02% and non-renewable energies accounted 88.98% of the total energy input. The study of greenhouse gas emissions showed that CO2, N2O and CH4 emissions were estimated to be 1417.04, 3.09 and 1.90 kg.ha-1, respectively. The global warming potential was calculated as 2413.38 kg equivalent of carbon dioxide per hectare, with the share of CH41%, CO2 58% and N2O 41%.

The best area for rapeseed production in this province is the western area and the southern area is not a suitable area for the development of this crop. However, by managing energy consumption, planting date and managing the use of chemical fertilizers, energy efficiency in canola production in the southern region of North Khorasan province can be improved.

Conventional tillage increases soil compaction and 25% water and wind erosion. It also causes decrease soil porosity and water capacity. In order to prevent this situation; conservational tillage is considered as an effective strategy. Conservational tillage have important role in soil erosion and improve its quality. Every year Moghan Agro-Industrial & Livestock (MAIL) Company costs a lot to do conventional tillage. In order to achieve the objectives of this study, an experiment was conducted in factorial pattern with completely randomized design with two factors, tillage method (Conventional tillage & No-tillage) and irrigation method (traditional irrigation & Sprinkler irrigation). Results showed that yield, average fuel consumption, traffic, water consumption and fuel consumption productivity index in No-tillage method is better than conventional tillage. Also, the results of the MCDM Engine software showed the Combination of No-tillage system with Sprinkler irrigation with CL*=0.98 (The relative proximity of the option to the ideal solution) is best method for minimum cost of production and maximum yield in silage corn. Therefore, No-tillage system with Sprinkler irrigation can be suitable method for sustainable production of Silage Corn in Moghan region.

Evaluation of energy consumption pattern and its efficiency in agricultural systems can play important role in recognition of agronomic ecological systems by highliting energy wasting points. In order to reach this point, it is essential to evaluate the incoming and outcoming energy to the system. In this research, paddy fields under cultivation of local cultivars were examined across different cities of Mazandaran. Initially the amount of incoming energy, thereafter the amount of outcoming energy were calculated based on agricultural incomes, then ultimately the total carbon dioxide emission were estimated. The results demonstrated that irrigation water, fossile fuel, nitrogen fertilizer and agricultural machinery were the maximum and fungicides, potassium and phosphorous fertilizer, the minimum incoming energy to the system. Babol and Amol cities, because of more cultivating area have maximum incoming energy and causing global warming. It was therefore postulated that effective use of energy in rice cultivation is an important factor in sustainable development, playing in economical saving, fossile fuel reservation and decreasing air pollution.

One serious challenge in agriculture during the 21st century is meeting the food demands of the growing population from restricted and decreasing per capita natural resources such as land, water, and minerals with minimum environmental degradation. But, developments in agriculture that heavily rely on chemical inputs such as synthetic fertilizers, pesticides, fossil fuels and other energy-intensive inputs, is having a serious impact on public health and the environment. Therefore, efficient use of resources and inputs is a primary and most vital implications for sustainable development of agriculture. Sustainability indices are quantitative values that can be used to evaluate the efficiency and quality of agroecosystems and are useful tools for making suitable decisions in its management (Mahdavi Damghani et al., 2006). These including energy flow indices, global warming potential (GWP), economic indices, environmental impact quotient (EIQ) of pesticides, efficiency of land, water and fertilizers use and etc.
In the present study, the sustainability of wheat and barley production systems lies in the Maragheh-Bonab plain in southern East Azerbaijan province in northwestern Iran were evaluated using the aforesaid indices. For this purpose, data was collected from 110 farmers by survey to determine crop production in the region. Secondary data was obtained from previous studies and statistics from organizations such as the Agricultural Ministry of Iran.
The results showed that the values of input energy, output energy and net energy in wheat production system (34412, 161462 and 127050 Mj ha-1, respectively) were higher than barley production system (29596, 126077 and 96480 Mj ha-1, respectively). Also, it was observed that the values of energy use efficiency and energy productivity of wheat (4.7 and 0.17 kg MJ−1, respectively) were significantly higher than that of barley (2.1 and 0.15 kg MJ−1, respectively). In terms of economic indices, despite of lower total cost of production in barley, the highest values of gross production value, net return, benefit to cost ratio and economic productivity were related to wheat production system. Our results are in agreement with the results of Sahabi et al. (2013). In terms of GWP and EIQ, wheat production had the higher values with compared to barley production. However, eco-efficiency (ratio of economic value to the environmental impact) values based on of GWP and EIQ was significantly higher for wheat (1.26 $ kg -1 CO2eq-1 and 37 $ EIQ-1) than barley (1.03 $ kg-1 CO2eq-1 and 31.4 $ EIQ-1). Also, land, water and fertilizer use indices for wheat were higher than barley. The land use efficiency, land production efficiency, economic land production efficiency, irrigation water productivity, economic irrigation water productivity, nitrogen use efficiency, phosphorous use efficiency and potassium use efficiency were 65.7%, 24.5 kg ha-1 day-1, 6.2 $ ha- 1 day-1, 1.6 kg m-3, 0.43 $ m-3, 56.7 kg kg-1, 136.4 kg kg-1 and 2401 kg kg-1 in wheat production system and 61.6%, 19.2 kg ha-1 day-1, 3.2 $ ha-1 day-1, 1.5 kg m-3, 0.26 $ m-3, 34.8 kg kg-1, 102.3 kg kg-1 and 376 kg kg-1 in barley production system, respectively.
It can be concluded that environmental impacts of pesticides and global warming effect per area in barley production system were lower than wheat production system. However, in terms of economic indices, inputs and energy use efficiency, wheat production system was superior to barley production system.

Over the past few decades, advances in technology have led to the increased use of energy and emissions of greenhouse gases. In this regard, researching the economic dimension of greenhouse gas emissions and their environmental effects, particularly in the present condition that their volume is increasing, has gained a lot of attention. This is due to the fact that the industrialization of modern societies has led to the use of fossil fuels such as coal, oil, and gas in production and services. Combustion of fossil fuels causes an increase in greenhouse gas emissions into the atmosphere of which carbon dioxide (CO2) is one of the most important. About 60% of greenhouse gas emissions in Iran is caused by the agricultural sector (Energy Balance, 2012) which is regarded as one of the main sources of such emissions. In the process of the production of agricultural products, greenhouse gases will be emitted as a result of inappropriate application of land and fertilizer, livestock, and the use of fossil energy (Behboodi et al., 2010) .So, in this study, the relationship between technological progress (land under modern irrigation and agricultural machinery), energy price and carbon dioxide emissions in Iranʼ s agricultural sector has been investigated.
For this purpose, a vector autoregressive model (VAR) and time series data during the period 1970-2012 were used .The reason for this choice of model, namely VAR, in this study is that it determines the long-running relationship between the variables and also has the ability to explain the short-run relationship between them. At first, the stationary degree of the variables was examined (Abrishami, 1996).
The results showed that, although not all variables are stationary at all levels, their first order differencing was stationary. After ensuring there is a convergence between variables, the results of model estimation are presented in two categories: the long-run relationship and the short-run relationship. The results showed that the energy price variable with a lag has a negative effect on CO2 emissions in the agricultural sector. With an increase in the energy price in agricultural sector energy demand, energy consumption will be reduced which leads, in turn, to reduced CO2 emissions. The machinery variable with a lag has a positive effect on carbon dioxide emissions in the agricultural sector. By assuming the same technology, increasing the number of such machinery results in more energy being consumed; increasing energy consumption leads to increased emissions of CO2. The land under modern irrigation variable with a lag has a negative effect on carbon dioxide emissions in the agricultural sector, with the short-run results confirming the long-run results. Share variables in the prediction error variance decomposition of carbon dioxide in the agricultural sector were also examined using the analysis of variance decomposition for a 10-year period. Results showed that energy price and land under modern irrigation have the most and the least effect on this variable both in the short- and long-run.
Therefore, one method to reduce carbon dioxide emissions without reducing of production is to improve energy intensity in the agricultural sector. If energy efficiency increases, it can reduce carbon dioxide emissions in this sector without reducing of production. Also, by employing multi-purpose machines it is possible to use less machinery and thus less use of energy. Modern technologies such as pressurized irrigation that reduce energy consumption and CO2 emissions are therefore recommended.

Climate change is one of the major concerns of the world which a part of that is derived from agricultural activities. Therfore, improving agricultural practices is considered as a strategy for mitigating the impact of climate change. The objectives of this study were to estimate the CO2 emission and global warming potential (GWP) in three rice production systems and identify the methods for reducing the energy use and CO2 emission. Three rice production systems including conservation, improved and conventional were studied in randomized complete block design with four replications a paddy field in Neka, Mazandaran, Iran. All field practices and data about production methods and inputs rate were monitored and recorded in 2012. Results showed that average of total energy input in production systems was 22793.02 MJ.ha-1 that the lowest energy input (16102.98 MJ.ha-1) was observed in conservation system. Electricity to pump of water for irrigation had the most contribution of energy input in production systems that was accounted as greatest global warming and CO2 emission. Nitrogen fertilizer and fuel were ranked in second and third grade of CO2 emission. Across the rice production, average GWP were estimated equal to 2307.33 kg CO2-eq ha-1. The lowest and highest GWP equal to 1640 and 2728 kg CO2-eq ha-1 were obtained in conservation and conventional systems, respectively. The lowest and highest GWP per unit energy input was gained in conservation and conventional system, respectively. Conservation system had the lowest GWP per unit energy output and improved system was ranked in seconed grade. Finally, it can be concluded that GWP has the positive correlation with field management and inputs use. Therfore, the lowest rate of CO2 emission and GWP were obtained in conservation system.

In this study, the energy indices of conventional rice production systems in Babolsar and Lahijan were investigated during 7010. Data were collected from 140 rice paddy farms in two provinces by carrying out a face-to-face questionnaire. The farms were selected based on random sampling method. Results demonstrated that the total input and output energy in Lahijan rice production systems were 4375433 and 177313311 MJ, respectively and, for input and output energy in Babolsar, were 40347377 and 17211732 MJ, respectively. Additionally, 333 of energy consumption in Guilan Province was assigned to water, 743 to electricity and 133 was allocated to N fertilizer. The character of energy consumption in Mazandaran Province was slightly different, since 413 was allocated to water, and 133 and 143 to N fertilizer and electricity, respectively. Ultimately, the results showed that the energy efficiency of rice production systems in Guilan was 7314, energy productivity was 031 and the proportion of water energy was 333. Furthermore, the values for the aforementioned indices in Mazandaran Province were 1315, 0311, and 413, respectively. It’s noticeable that the vast majority of input energy was due to using water logging irrigation systems, obtaining it from groundwater resources through use of electric power which, consequently, reduced energy efficiency and productivity in the rice production systems studied. Regarding this, the employment of new technologies for the proper management of water resources recommended.