Behnam Kamkar; Pooya Aalaee Bazkiaee; Parysa Alizadeh Dehkordi; Ebrahim Amiri
Abstract
Introduction: Increasing greenhouse gases will have different effects on crop yields, so that the interaction of these effects may increase or decrease yields. Crop simulation models have been used to investigate different levels of crop and environmental managements. The aim of this study was to investigate ...
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Introduction: Increasing greenhouse gases will have different effects on crop yields, so that the interaction of these effects may increase or decrease yields. Crop simulation models have been used to investigate different levels of crop and environmental managements. The aim of this study was to investigate the AquaCrop model based on past, present and future climate in Rasht city located in Guilan Province to achieve maximum water productivity and rice grain yield.Material and methods: In order to study the changes in rice yield, water balance and productivity in Rasht city located in Gilan province under the past, present and future climate, the AquaCrop model was used. For this purpose, long-term data (over 30 years) were used to evaluate the yield and water balance in rice cultivation in the past and present climate. Also, using LARS-WG6 software, meteorological data for the next 83 years were generated based on the available daily meteorological data. The AquaCrop model was evaluated in the past, present and future climates based on daily data of minimum and maximum temperatures, precipitation and sun hours. The studied treatments included four levels of irrigation including 55, 70, 85 and 100% of water requirement and the planting dates were April 21th, May 11th and May 31th. By examining the effect of different treatment levels based on RCP 4.5 and RCP 8.5 climate change scenarios, the rate of changes in grain yield, evapotranspiration and water productivity based on evapotranspiration in the past, present and future climates were investigated. Also, the best irrigation treatment and planting date were introduced to increase rice yield and reduce water consumption.Results and discussion: The evaluation results showed that the LARS-WG6 model is able to simulate the climatic components including temperature, precipitation and radiation with high accuracy. The results showed that the minimum and maximum temperatures increased during the climate change scenarios and the amount of radiation and precipitation decreased. The result of rice biomass and grain yield under RCP 4.5 and RCP 8.5 showed that the highest grain and biomass yield was obtained in irrigation of 100% of water requirement and planting date on April 21th. The study of water productivity showed that irrigation treatment of 100% of water requirement and planting date of May 31th had an effective role in increasing soil water storage and reducing evapotranspiration from the soil surface. The highest water productivity in grain production based on evapotranspiration was obtained in irrigation of 100% of water requirement and planting date was May 31th.Conclusion: According to the obtained results, considering the water consumption productivity and yield and problems that will exist in the future including water shortage, it seems that late cultivation of rice in conditions of water shortage is a good solution, but under conditions where there is no water shortage, early cultivation of rice, such as April 21th, can increase the production. The study of irrigation levels showed that grain production is the most effective factor in increasing water use productivity and the use of low irrigation levels will not play an effective role in increasing water productivity.
Mohammad Taghi Feyzbakhsh; Nasibe Rezvantalab; Parisa Alizadeh
Abstract
Introduction: In recent years, energy consumption in agriculture has increased dramatically, and modern agriculture has become very scarce in energy. Most of the energy used to produce agricultural products is due to the use of inputs such as machinery, fossil fuels, fertilizers and pesticides, that ...
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Introduction: In recent years, energy consumption in agriculture has increased dramatically, and modern agriculture has become very scarce in energy. Most of the energy used to produce agricultural products is due to the use of inputs such as machinery, fossil fuels, fertilizers and pesticides, that inappropriate use of these inputs while reducing energy efficiency in production also causes problems for human health and the environment. At the moment, due to the energy crisis in the world, it is necessary to study more about energy consumption and find solutions for its optimal use (Darlington, 1997). This study was conducted to identify the energy evolution and global warming potential in wheat and barley production in northern lands of Gorgan plain and in the city of Aq-Qala. So that appropriate strategies can be identified to prevent energy wasting and reduce the environmental impact of resources. Material and methods: For this study 95 and 83 farmers were selected for wheat and barley production in Aq-Qala city, respectively. The data including (machines, seeds, fertilizers, fuel and pesticides) were collected by questionnaire. Then fuel, input and output energy, energy evaluation indices and global warming potential (kg CO2.ha-1) were calculated by related coefficients (Soltani et al., 2013). Results and discussion: The results showed that the highest direct input energy in wheat and barley production belonged to fuel consumption were 38.8% and 46.8% respectively. Also, the highest indirect input energy was obtained with 31.3 and 19.1 percent for nitrogen fertilizer for wheat and barley fields, respectively. The ratio of the energy output to the input for rainfed wheat and rainfed barley were calculated 5.01 and 5.03, respectively. Also, global warming potential in wheat and barley production was 943.9 and 739.1 (kg eq-CO2 ha-1), respectively. In another study, greenhouse gas emissions for wheat production in Golestan province were estimated about 1200 kg CO2.ha-1 (Rezvantalab et al., 2015). Also, the results showed that increased fuel and fertilizer consumption will increase the amount of input energy in both crop production and increase the production of greenhouse gases. Therefore, the use of more efficient machinery and equipment, which reduces fuel consumption, and also, considering proper crop rotation and using organic fertilizers can reduce energy consumption, increase energy efficiency and reduce the global warming potential of rainfed wheat and rainfed barley production. Conclusion: The results showed that the fuel consumed in both products had the highest input energy input, followed by fertilizer, especially nitrogen fertilizer, Therefore, the reduction of fuel consumption by using combinators and the use of protection culture systems (minimum tillage) is recommended to reduce the amount. It is also recommended to observe crop rotation and rotation with cover crops that are able to stabilize nitrogen as one of the ways to reduce fertilizer use. It is suggested that yield increase by improving management operations, optimum use of fertilizers, pest control, and then, will improve energy efficiency.
