The Role of Conservation Tillage in Sustainable Agriculture with the Approach of Optimal Energy Consumption

Energy consumption in agriculture products is directly related to agricultural tillage systems. This study investigated the role of conservation tillage on optimal energy consumption and sustainable rural development in the production of irrigated wheat in Miami City. The required information is obtained by completing a questionnaire with face-to-face interviews based on outputs and inputs. The input and output energy and energy indexes were investigated using energy equivalence coefficients. The highest and lowest input energy consumption was related to conventional tillage (47886 MJ/ha) and no-tillage (40448 MJ/ha), respectively. In comparison with other inputs, nitrogen fertilizer accounted for the largest share of input energy in all three conventional tillage (35%), low tillage (38%), and no-tillage (41%). After nitrogen fertilizer, fuel energy, irrigation water, and electric energy accounted for the highest amount. Regarding fuel energy, conventional tillage ranked first with 16% of the total and no-tillage ranked last with 6.6%. In all three tillage methods, more than 75% of energy consumption is provided from non-renewable sources. The results showed that the conservation tillage system is an important step towards optimal use of inputs and energy in wheat production. In addition, the development of conservation agriculture can reduce the production of greenhouse gases and environmental damage and lead to the stability of production.
Introduction
Excessive consumption of energy in agriculture has been noticed by sustainable development experts as one of the important challenges that threaten the environment. Energy consumption in agriculture products is directly related to agricultural tillage systems. Studies conducted in Iran have shown that energy consumption in the agricultural sector is increasing every year. In the past, the main goal in agricultural production has been mainly focused on increasing yield and production. Whereas, today, economic and sustainable production is more important due to the improvement of product quality, reduction of input consumption, and preservation of natural resources and the environment. Considering the excessive consumption of fossil fuels and greenhouse gas emissions, all efforts are aimed at reducing energy consumption, especially fossil fuels, and greenhouse gas emissions as much as possible to achieve sustainability in production. Therefore, it is necessary to evaluate the energy consumption and its environmental effects on the emission of greenhouse gases in wheat production. To investigate the role of conservation tillage in the sustainable development of agriculture, with the approach of reducing the amount of energy consumed in irrigated wheat production, this research was conducted in Miami city.
Materials and Methods
In this study, the effect of tillage methods (conventional tillage, reduced tillage, and no-tillage) on optimal energy consumption in irrigated wheat production was investigated. Conventional tillage operations include (plowing with a moldboard plow + disc), reduced tillage (plowing with a compound tiller), and no-tillage (direct planting). Data collection was done by filling out the form with face-to-face interviews with farmers in the region, Experienced experts, and mechanized service companies in 60 wheat production farms. Energy efficiency, energy productivity, energy intensity, and net energy were calculated using standard relationships. Energy consumption was divided into direct energies (manpower, fossil fuels, electric energy, and irrigation water), and indirect energies (agricultural machines, chemical fertilizers, pesticides and herbicides, and seeds). To calculate the global warming potential, carbon dioxide was considered as the basis for determining the effect of greenhouse gases on global warming, and the warming potential of other greenhouse gases was measured according to this gas.
Results and Discussion
The amount of energy related to each of the inputs was calculated by multiplying the consumption amount by the energy equivalent of each input. The highest and lowest input energy was related to the conventional tillage (47886 MJ/ha) and direct planting (40448 MJ/ha), respectively. These results showed that in the conventional method compared to the conservation methods, there is an increase in mechanized agricultural operations, and this problem causes an increase in fuel and energy consumption. Other researchers (Pazuki Tarodi et al., 2016) reported similar results. In comparison with other inputs, nitrogen fertilizer accounted for the largest share of input energy in conventional tillage (35%), reduced tillage (38%), and no-tillage planting (41%). The greater share of nitrogen fertilizer energy in different production systems is due to the relatively high energy equivalent and high consumption of nitrogen fertilizer in water wheat cultivation. By conducting soil tests and managing nitrogen fertilizer consumption, it is possible to reduce input energy consumption and increase energy efficiency. After nitrogen fertilizer, fuel, and electric energy accounted for the highest amount of energy. More consumption of fuel and related energy in the conventional method is due to heavy plowing operations and more operations in land preparation compared to no-tillage. Other researchers (Rajabi et al., 2013; Safa, 2008) reported similar results. The average energy intensity in the three methods of conventional tillage, reduced tillage, and no-tillage was 4, 3.7, and 3.5 megajoules per kg respectively, which no-tillage has a lower yield due to less energy consumption compared to the other two methods have less energy intensity (less energy consumption per unit of product production). The intensity of energy consumption is proportional to the intensity of tillage operations. By reducing tillage operations, fuel consumption and energy consumption intensity will decrease. Yousefi et al. (2018) reported obtained similar results. The average energy efficiency in the conventional tillage, reduced tillage and no-tillage was 3.3%, 3.7%, and 3.9% respectively.  No-tillage had higher energy efficiency than the other two methods due to less energy consumption. The reason for the low energy efficiency in conventional tillage can be related to its high dependence on inputs and excessive energy consumption for production. The amount of energy efficiency in conventional tillage was lower than in conservation tillage methods. The highest and lowest values ​​of global warming potential were related to the conventional tillage (6480.9 kilograms of CO2 equivalent per hectare) and no tillage (5479.7 kilograms of CO2 equivalent per hectare), respectively. Other researchers (Yousefi et al., 2016, Mohamadzadeh et al., 2018) reported similar results. The high global warming potential in conventional tillage is due to the number of tillage operations and the energy-intensive plowing operation, which causes more fuel consumption and consequently increases the global warming potential in comparison with no-tillage.
Conclusion
In this study, the trend of energy flow and global warming potential was investigated in conventional tillage, low tillage, and no-tillage methods in the production of irrigated wheat. Results showed, that the amount of energy input in the conventional tillage (47776 megajoules) compared to reduced tillage (43451 megajoules) and no-tillage (40448 megajoules) was more, and this caused the energy efficiency in the conventional tillage to be lower than the conservation methods. The most direct and indirect input energy was related to diesel fuel and nitrogen fertilizer, respectively. Excessive use of agricultural machines and performing multiple operations are the main factors for increasing fuel consumption and a significant increase in carbon dioxide emissions. Also, the high consumption of nitrogen fertilizer and irrigation water leads to an increase in energy consumption and the production of greenhouse gases and increases the potential for global warming. Therefore, with more management in accurate and timely consumption of inputs, using agricultural machines at the optimal time, and avoiding additional operations, it is possible to greatly reduce the creation of greenhouse gases and environmental hazards.