جستجوی مقالات مرتبط با کلیدواژه "کیفیت اکوسیستم" در نشریات گروه "اکولوژی"

Rice (Oryza sativa L.) is one of the most important food resources of more than half of the world's population. Rice, as the second most strategic crop, is the most important cereal after wheat. Excessive use of renewable and non-renewable resources in the agricultural sector, chemical control of rice diseases, and irreparable environmental damage of these systems potentially have a variety of environmental impacts on agricultural systems, such effects can be assessed by the life cycle assessment (LCA) approach. The purpose of the present research is to assess of knowing and comparing the trend of environmental pressure of the second and ratoon cropping systems of rice production in the paddy fields.

This research was conducted in 2020 in the paddy fields of Amol city with the focus on recognizing and comparing the trend of environmental pressure in rice production in the second and ratoon cropping systems. Accordingly, all data related to the second and ratoon rice cropping systems in different stages of rice production, from planting to harvesting phases, was collected in Amol region. In this study, to classify and quantify the environmental effects of rice production in two cropping systems using the LCA method are addressed. Furthermore, the environmental impacts of these systems such as global warming potential, eutrophication, and acidification of water and soil were also calculated. In this study, the functional unit of rice production systems were considered equivalent to one ton of paddy. Therefore, in order to evaluate the emission of greenhouse gases and energy in paddy fields, the required information was collected and interviewed by paddy farmers.

The findings of this study indicated that the highest global warming potential of rice was related to the rice second cropping system about 1896.92 kg carbon dioxide per ton of produced rice. Evaluation of the LCA in rice production process showed that in the group of environmental impact of global warming, about 1673.99 kg equivalent of carbon dioxide to the atmosphere has been released per ton of rice in ratoon cropping system. Direct emissions from on-farm activities in all two studied systems have played a major role in increasing global warming. The source of these pollutants is the combustion of diesel used in agricultural implements and machinery, accompanied by the emission of nitrogen dioxide, nitrogen oxides and other nitrogenous compounds resulting from the use of nitrogen fertilizers. Also, rice second cropping systems had a greater impact on the three categories of human health damage, ecosystem quality, and climate change than ratoon cropping systems. Moreover, the values of damages on the quality of the ecosystem in these systems were about 10089.08 and 7146.58 PDF*m2 * yr in the second and ratoon cropping systems, respectively. In addition, both rice production systems have shown the greatest impact on ecosystem quality and then on human health. Direct emissions from on-farm activities in the two studied systems have played a major role in increasing global warming. The source of these pollutants is the combustion of diesel used in agricultural implements and machinery, as well as the emission of nitrogen dioxide, nitrogen oxides and other nitrogenous compounds resulting from the use of nitrogen fertilizer.

The results revealed that the rice second cropping system had the higher amount of total emissions than the ratoon cropping system, therefore, rice ratoon production system is more environmentally friendly than the rice second cropping systems.
Acknowledgements
This research was funded by the Sari Agricultural Sciences and the Natural Resources University (SANRU) under contract No. d-110-99-16690. We would also like to thank the esteemed rice farmers in Amol region, Mazandaran province, Iran for their cooperation.

 Rice, as the second most strategic crop, is the most important cereal after wheat. In Iran, rice is so essential that people consume it as part of their main meal at least once a day. Due to the increase in consumption inputs in conventional paddy systems, chemical control of rice diseases and consequently increase in consumption costs, irreparable environmental damage of these systems, always adds to the need to pay attention to alternative systems. Prediction of agricultural energy output and environmental impacts play the most important role in conservation of environment as well as energy management. A wide range of methods tapping into environmental performances related to agricultural activities have been proposed, among which the known life cycle assessment (LCA) method is deemed mostly employed. As a standard method which aims for holistic evaluation of the environmental resources and impact, LCA measures the process of a product's entire life cycle, or in other words, the analysis of the possible environmental impacts any product bears during their life would be assessed by LCA.

 This research was conducted in rice fields located in Mazandaran province in Babol, Fereydounkenar, and Amol counties as the main rice paddy center of Mazandaran province, in 2019 cropping season. Each of the systems was examined in terms of energy components and environmental impacts. In this study, to classify and quantify the environmental effects of rice production in various cropping systems using LCA method and also the energy components and energy efficiency in these systems are addressed. Therefore, in order to evaluate the emission of greenhouse gases and energy in paddy fields, the required information was randomly collected some farms through direct interviews with the rice growers of Mazandaran. In this regard, the sample size is calculated by using Cochran's formula.

 The findings of this study showed that the maximum amount of input energy equal to 60225.42 MJ / ha in conventional systems and the minimum values of 18662.14 MJ / ha were allocated to the organic system. Diesel fuel input energy had the largest share of total input energy. The highest energy efficiency of 0.17 kg per MJ and energy ratio of 2.57 was allocated to the organic system. Also, the evaluation of life cycle in rice production showed that in the global warming group of environmental impact by CML2 baseline method, for each ton of paddy produced in conventional, low-input and organic systems, respectively, about 2408.90, / 85.90, respectively. 1777 and 7993/1193 kg of carbon dioxide equivalent to the atmosphere are released. Direct emissions from on-farm activities in all three studied systems have played a major role in increasing global warming. The source of these pollutants is the combustion of diesel used in agricultural implements and machinery, as well as the emission of nitrogen dioxide, nitrogen oxides and other nitrogenous compounds resulting from the use of nitrogen fertilizer.

 According to the results of this research work, from the environmental perspective, organic system has highly the best potential of being recommended following by low external input system in order to reach environmentally friendly agriculture as sustainable cultural operations in comparison with conventional cultivation practices. Farther, the results showed that the conventional system had the highest amount of total emissions and then the low input system is in the next position. Obviously, the organic system is the most environmentally friendly system and the conventional system has the highest amount of emissions. In order to give a broader evaluation of the organic and some low input systems, studies on such issues should be highly continued.