ehsan khodarezaie; Korous Khoshbakht; Hadi Veisi; Mohammad Reza Nazari
Abstract
IntroductionEnergy use in agriculture has grown faster than other sectors of the global economy. In developing countries, most agricultural systems consume significant amounts of energy to increase production and food security. Energy consumption leads to the emission of greenhouse gases and environmental ...
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IntroductionEnergy use in agriculture has grown faster than other sectors of the global economy. In developing countries, most agricultural systems consume significant amounts of energy to increase production and food security. Energy consumption leads to the emission of greenhouse gases and environmental pollutions in the agriculture sector. Besides, the use of fossil fuels in the production process and transfer of inputs emits greenhouse gases, which in turn cause global warming and climate change. Analyzing and good understanding of energy flow and Greenhouse Gas (GHG) emissions in agricultural production systems can help to optimize crop management practices thereby reducing environmental problems. Iran's average energy consumption is three times higher than the world average.Groundwater is the main source of agricultural water in arid and semi-arid areas. Electricity used in irrigation pumps consumes a large of energy and emits GHGs. Qazvin plain is one of the most important agricultural plains in Iran, which along with the use of groundwater, has the largest irrigation canal network in the country. Differences in agricultural water supply sources can lead to differences in energy consumption and greenhouse gas emissions as electricity and other inputs may be affected. Wheat, barley, alfalfa and maize silage are major crops in Qazvin plain. Alfalfa and maize silage need relatively a high irrigation water requirement. This paper evaluates the energy flow and Global Warming Potential (GWP) of alfalfa and maize silage farms with two different water supply sources (well and canal) in Qazvin plain.Materials and MethodsThe data were collected through face-to-face interviews with farmers in the year 2018. Energy indices were estimated based on the analysis of farm inputs and outputs. Global Warming Potential was calculated using the Life Cycle Assessment (LCA) method and SimaPro 8.2 software. GHGs were calculated using the conversion coefficients presented by the IPCC GWP 100 method. Results and DiscussionThe output energy values of maize silage and alfalfa were calculated as 232726, 191812 MJ ha-1 for well water irrigation system and 234167 and 248060 MJ ha-1 for the canal water irrigation, respectively. Results showed higher net energy values for alfalfa (172778 MJ ha-1) and maize silage (167618 MJ ha-1) in canal water irrigation system compared to well water irrigation (131300 MJ ha-1 and 60112 MJ ha-1 for corn silage and alfalfa, respectively) mainly because of the relatively lower input energy. The results showed that the highest and lowest values of input energy were related to alfalfa production with well water irrigation (131700 MJ ha-1) and maize silage with canal water irrigation (66548 MJ ha-1), respectively. Also, the energy use efficiency of maize silage (3.5) and alfalfa (3.3) were higher in canal water irrigation systems compared to well water irrigation systems (2.3 for maize silage and 1.46 for alfalfa). In the well water irrigation systems, GWP was calculated to be 7466.9 kg CO2-eq ha−1 and 7995.7 kg CO2-eq ha−1 for maize silage and alfalfa, respectively. These values were 5533.3 kg CO2-eq ha−1 and 4947.6 kg CO2-eq ha−1 for maize silage and alfalfa in the canal water irrigation systems, respectively. Electricity and direct emission showed the highest share of total energy consumption and GHG emission.ConclusionGenerally, our results showed that energy consumption and GWP were lower in the canal irrigation systems than well irrigation systems mainly as a result of electricity used for water pumping in well irrigation operations. It can be inferred from the present study that for efficient use of resources and decreasing environmental problems in the study area, practices such as optimal management of irrigation water, conservation tillage, and optimal management of chemical fertilizers can help to achieve these goals.
Nasibe Rezvantalab; Afshin Soltani; Ebrahim Zeinali; Salman Dastan; Alireza Foroughnia
Abstract
Introduction: Inputs such as chemical fertilizers, fossil fuels, electricity, seed, and machinery consume energy in soybean production. This energy consumption is expected to cause Greenhouse Gases Emissions (GHG). Increasing the concentration of these gases in the atmosphere could lead to Global Warming. ...
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Introduction: Inputs such as chemical fertilizers, fossil fuels, electricity, seed, and machinery consume energy in soybean production. This energy consumption is expected to cause Greenhouse Gases Emissions (GHG). Increasing the concentration of these gases in the atmosphere could lead to Global Warming. The purpose of this study was to investigate the energy consumption and GHG in soybean production in Golestan Province, Iran. Material and methods: In this study, 140 farmers were selected to investigate the soybean production systems in Golestan Province in northeastern Iran. The data of consumed energy (machines, seeds, fertilizers, fuel, pesticides, human labor, and electricity) were collected by a questionnaire. Then fuel, input and output energy, energy indices, and global warming potential (kg eq-CO2/ha) were calculated by related coefficients. Results and discussion: Based on results, fuel and energy requirements for soybean production were estimated 210.83±0.09 L/ha and 19036.08±2.53 MJ/ha, respectively. Also, GHG emissions were calculated 2306.85±3.17 kg eq-CO2/ha. Fossil fuel and electricity consumption had the highest energy consumption and GHG emissions values, respectively, so that 62% of the total energy consumption and 75% of the total GHG emission belonged to electricity and fossil fuel consumption, respectively. Energy output derived from soybean was 42124.95±0.73 MJ/ha. The output-input ratio was estimated 2.21±0.01. Net energy gain was raised by increasing the seed yield and decreasing the input consumption such as electricity, fossil fuel, and N-fertilizer. Energy productivity was calculated 0.147±0.01 Kg/MJ. On average, 2306.85±3.17 kg eq-CO2/ha greenhouse gases were released into the atmosphere for soybean seed production. Conclusion: Focusing on optimal consumption of fossil fuels and decreasing the electricity consumption in irrigation is essential for reducing the energy consumption and greenhouse gas emissions for soybean production in Golestan Province, Iran.
