Assessing the life cycle cost (LCC) and energy of soybean agroecosystems in Mazandaran province

Energy is a limiting factor for agricultural sustainability due to costs and supply security. Agriculture section as one of the world's major food suppliers, has faced challenges in recent times due to increased energy consumption trends. This rise in energy consumption has led to increased production costs, negative impacts on food security, and environmental concerns. Therefore, achieving a balance between energy demand and supply in agricultural systems and assessing their economic performance is essential. With the recognition that soybean [Glycine max (L.) Merril] plays a crucial role in ensuring food security; a study was conducted in 2019 to analyze the energy flow and economic costs of soybean production at the provincial level in Mazandaran, Iran.

To assess the economic efficiency and energy consumption pattern in soybean farms, data were collected through direct interviews with 301 soybean farmers. The inputs used for estimating energy efficiency per hectare of soybean cultivation included fossil fuels, machinery, human labor, seeds, irrigation water, electricity, fertilizers, and chemical pesticides. The produced soybean grain was also considered as an output energy source. Life Cycle Cost (LCC) methodology was employed to evaluate the economic efficiency of soybean production; for this purpose, the farm gate was defined as the system boundary, and one hectare of soybean farm was taken as the base unit for all analyses. The social costs of emissions, in addition to the fixed and variable production costs that are addressed in most studies, were evaluated and analyzed. In the current study, the social costs of pollutant emissions in soybean production agroecosystems were considered from two aspects: (1) emissions on the farm and (2) pollutants generated from electricity generation. These costs were estimated using the standard coefficients established in previous researches.

Based on the results, diesel fuel, nitrogen chemical fertilizers, and consumed seeds had the highest shares of total input energy in soybean production with 47.90%, 19.61%, and 13.53% respectively. The average energy productivity for soybean production in Mazandaran province was calculated to be 0.16 kg MJ-1. From this point of view, Galugah county was the best with 0.25 kg MJ-1, while Amol was the worst with 0.11 kg MJ-1 compared to other scrutinized counties. In terms of the type of consumed energy, the results indicated that the current soybean production in Mazandaran province is not sustainable due to heavy reliance on non-renewable energy resources such as diesel fuel and nitrogen chemical fertilizers. The LCC of soybean production in Mazandaran province, including variable, fixed, and social costs resulting from emissions, was estimated to be an average of $327.90 per hectare. Among these costs, variable costs accounted for the highest share in soybean production in the region with $299.52 per hectare (approximately 91%).The average wage paid to owners of agricultural machinery and equipment was $141.85 per hectare (equivalent to 47.36%), and the average wage for human labor was $85.77 per hectare (equivalent to 28.64%). These two factors were the first and second most significant contributors to production costs for the soybean crop, respectively. Together, they accounted for approximately 69% of the total production cost (LCC). Carbon dioxide emissions, accounting for 41.16% (mainly due to diesel fuel combustion and urea fertilizer consumption on the farm), constituted a significant portion of the social cost resulting from emissions (at $7.38 per ton).

In general, the results of the survey of 301 farms indicated that soybean production in Mazandaran province, with an average energy efficiency of 2.43, is economically justifiable in terms of energy balance and constitutes a profitable agricultural product in the region, with a profit-to-cost ratio of 1.86.