• Energy Research

The exploitation of natural resources for agriculture is growing to fulfill the demand for food, which requires the rational use of inputs for sustainable production. Brazilian agricultural production stands out on the international scene. For instance, corn is one of the most exported products in Brazil, which is possible through the planting in the second crop season within a year, called the “off-season”. In addition to being a technique that allows soil conservation, it also reduces the use of inputs and soil tillage. The agricultural production systems require a large amount of energy throughout their processes, mainly through inputs and fuels. Energy flows allow for the identification of the efficiency of the production system and, consequently, its sustainability. Indicators regarding net energy gain per area (Energy balance) and energy profitability (Energy Return on Investment) were applied. The first-season system presented higher energy demand when compared to the second-season system, with a difference of 10.24 GJ ha−1 between the conventional ones and 10.47 GJ ha−1 between the transgenic ones. However, the indicators showed higher energy efficiency in the transgenic off-season corn production, in which the return on energy was 55% higher, and the energy incorporation was 35% lower when compared to conventional first-season corn.

The exploitation of natural resources for agriculture is growing to fulfill the demand for food, which requires the rational use of inputs for sustainable production. Brazilian agricultural production stands out on the international scene. For instance, corn is one of the most exported products in Brazil, which is possible through the planting in the second crop season within a year, called the “off-season”. In addition to being a technique that allows soil conservation, it also reduces the use of inputs and soil tillage. The agricultural production systems require a large amount of energy throughout their processes, mainly through inputs and fuels. Energy flows allow for the identification of the efficiency of the production system and, consequently, its sustainability. Indicators regarding net energy gain per area (Energy balance) and energy profitability (Energy Return on Investment) were applied. The first-season system presented higher energy demand when compared to the second-season system, with a difference of 10.24 GJ ha−1 between the conventional ones and 10.47 GJ ha−1 between the transgenic ones. However, the indicators showed higher energy efficiency in the transgenic off-season corn production, in which the return on energy was 55% higher, and the energy incorporation was 35% lower when compared to conventional first-season corn.

ABSTRACT: Soybean is the main product of Brazilian agribusiness, both production and income. Considering the increase in food and energy demand and the search for more sustainable production systems, this study aimed to analyze inputs and energy use of a possible area of expansion of soybean production: a system under sub irrigation management located in a lowland area of Cerrado biome, northern region of Brazil. Its environmental performance was compared to other Brazilian locations among them traditionally soybean producers. The evaluation and comparison was made through material and energy flow tools in order to determine the inputs embodied per area, as well as energy demand, availability and efficiency in the analyzed production system. Energy demand (IE) and energy availability (OE) of the analyzed production system were 7.6 and 57.1 GJ ha-1, respectively. Energy balance (EB) was 49,5 GJ ha-1, energy return over investment (EROI) was 7.5 and embodied energy in grains (EE) was 2,2 MJ kg-1, respectively. Highest energy consumption was due to the use of fertilizers, fuel and herbicide. The system is energy efficient, since it provides more energy than demands, and efficient when compared to usual production systems in other regions, however it is highly dependent on non-renewable energy.

ABSTRACT: Soybean is the main product of Brazilian agribusiness, both production and income. Considering the increase in food and energy demand and the search for more sustainable production systems, this study aimed to analyze inputs and energy use of a possible area of expansion of soybean production: a system under sub irrigation management located in a lowland area of Cerrado biome, northern region of Brazil. Its environmental performance was compared to other Brazilian locations among them traditionally soybean producers. The evaluation and comparison was made through material and energy flow tools in order to determine the inputs embodied per area, as well as energy demand, availability and efficiency in the analyzed production system. Energy demand (IE) and energy availability (OE) of the analyzed production system were 7.6 and 57.1 GJ ha-1, respectively. Energy balance (EB) was 49,5 GJ ha-1, energy return over investment (EROI) was 7.5 and embodied energy in grains (EE) was 2,2 MJ kg-1, respectively. Highest energy consumption was due to the use of fertilizers, fuel and herbicide. The system is energy efficient, since it provides more energy than demands, and efficient when compared to usual production systems in other regions, however it is highly dependent on non-renewable energy.

Climate, area expansion and the possibility to grow soybean and maize within a same season using the no-tillage system and mechanized agriculture are factors that promoted the agriculture growth in Mato Grosso State – Brazil. Mechanized operations represent around 23% of production costs for maize and soybean, demanding a considerably powerful machinery. Energy balance is a tool to verify the sustainability level of mechanized system. Regarding the sustainability components profit and environment, this study aims to develop a deterministic model for agricultural machinery costs and energy demand for no-tillage system production of soybean and maize crops. In addition, scenario simulation aids to analyze the influence of fleet sizing regarding cost and energy demand. The development of the deterministic model consists on equations and data retrieved from literature. A simulation was developed for no-tillage soybean production system in Brazil, considering three basic mechanized operations (sowing, spraying and harvesting). Thereby, for those operations, three sizes of machinery commercially available and regularly used (small, medium, large) and seven levels of cropping area (500, 1000, 2000, 4000, 6000, 8000 and 10,000 ha) were used. The developed model was consistent for predictions of power demand, fuel consumption and costs. We noticed that the increase in area size implies in more working time for the machinery, which decreases the cost difference among the combinations. The greatest difference for the smallest area (500 ha) was 22.1 and 94.8% for sowing and harvesting operations, respectively. For 4000 and 10,000 ha, the difference decreased to 1.30 and 0.20%. Simulated scenarios showed the importance of determining operational cost and energy demand when energy efficiency is desired.

Climate, area expansion and the possibility to grow soybean and maize within a same season using the no-tillage system and mechanized agriculture are factors that promoted the agriculture growth in Mato Grosso State – Brazil. Mechanized operations represent around 23% of production costs for maize and soybean, demanding a considerably powerful machinery. Energy balance is a tool to verify the sustainability level of mechanized system. Regarding the sustainability components profit and environment, this study aims to develop a deterministic model for agricultural machinery costs and energy demand for no-tillage system production of soybean and maize crops. In addition, scenario simulation aids to analyze the influence of fleet sizing regarding cost and energy demand. The development of the deterministic model consists on equations and data retrieved from literature. A simulation was developed for no-tillage soybean production system in Brazil, considering three basic mechanized operations (sowing, spraying and harvesting). Thereby, for those operations, three sizes of machinery commercially available and regularly used (small, medium, large) and seven levels of cropping area (500, 1000, 2000, 4000, 6000, 8000 and 10,000 ha) were used. The developed model was consistent for predictions of power demand, fuel consumption and costs. We noticed that the increase in area size implies in more working time for the machinery, which decreases the cost difference among the combinations. The greatest difference for the smallest area (500 ha) was 22.1 and 94.8% for sowing and harvesting operations, respectively. For 4000 and 10,000 ha, the difference decreased to 1.30 and 0.20%. Simulated scenarios showed the importance of determining operational cost and energy demand when energy efficiency is desired.

Cattle is the main protein source in Brazil and cattle production depends on preserving forage in order to decrease the influence of dry periods on grass production. To minimize such problems, some new techniques have been created to increase the yield which also leads to energy demand increase. Energy balance is a vital tool to evaluate the efficiency of energy consumption in production systems. There is no standard methodology established for this determination. It is also difficult to analyze different management options because of the complexity of the production systems and the interactions among variables. Therefore the purpose of this study is to develop a methodology that supports the development of a model, using a spreadsheet, and to use it to analyze the energy balance of production systems. The model was applied to a traditional production system of maize (Zea mays L.) silage and a Bermuda grass (Cynodon spp.) haylage. The gross energy balance presented was 14.1 energy units of output per energy units of input for maize silage and 0.98 for haylage. For the digestible energy balance, the values were 9.1 and 0.99, respectively. The total energy demanded was 74.3% in maize silage fertilizations and 99.7% in haylage irrigation. Yield and dry matter contents were indicated in a sensitivity analysis as the main critical variables for maize, whereas for haylage, it was not possible to indicate any. The best alternative scenarios for improving energy efficiency in maize silage and haylage production were the reductions of fertilizer concentration and irrigation use, respectively.

Cattle is the main protein source in Brazil and cattle production depends on preserving forage in order to decrease the influence of dry periods on grass production. To minimize such problems, some new techniques have been created to increase the yield which also leads to energy demand increase. Energy balance is a vital tool to evaluate the efficiency of energy consumption in production systems. There is no standard methodology established for this determination. It is also difficult to analyze different management options because of the complexity of the production systems and the interactions among variables. Therefore the purpose of this study is to develop a methodology that supports the development of a model, using a spreadsheet, and to use it to analyze the energy balance of production systems. The model was applied to a traditional production system of maize (Zea mays L.) silage and a Bermuda grass (Cynodon spp.) haylage. The gross energy balance presented was 14.1 energy units of output per energy units of input for maize silage and 0.98 for haylage. For the digestible energy balance, the values were 9.1 and 0.99, respectively. The total energy demanded was 74.3% in maize silage fertilizations and 99.7% in haylage irrigation. Yield and dry matter contents were indicated in a sensitivity analysis as the main critical variables for maize, whereas for haylage, it was not possible to indicate any. The best alternative scenarios for improving energy efficiency in maize silage and haylage production were the reductions of fertilizer concentration and irrigation use, respectively.