Sustainability assessment of corn production in conventional and conservation tillage systems

To develop sustainable cropping systems, the coherence between economic, environmental, and energy aspects must be considered. We aimed to assess the sustainability of corn (Zea mays) production using four tillage systems which varied in the intensity of soil disturbance (i.e., conventional till with moldboard plow (MP), conventional till with chisel plow (CP), strip-tillage (ST), and no-till (NT)) by performing life cycle assessment (LCA) analysis and Material Flow Cost Accounting (MFCA). It is common that material and energy wastage is not considered in sustainability assessment studies. When material and energy wastes are calculated in monetary terms, the hidden costs of production will be revealed. Simultaneous application of LCA and MFCA methods in sustainability assessments can provide such valuable information. Cradle-to-farm gate was considered as the system boundary in LCA-MFCA. The total annual energy input for corn production using MP, CP, ST, and NT was found to be 37472 MJ ha⁻¹ (3092 MJ t⁻¹), 36384 MJ ha⁻¹ (3290 MJ t⁻¹), 33717 MJ ha⁻¹ (3309 MJ t⁻¹), and 32889 MJ ha⁻¹ (2764 MJ t⁻¹), respectively. As energy demand increased, yield per ha also increased in all tillage systems except in NT in which yield increase was concurrent with improved energy efficiency. The gross value was calculated as 1470 $ ha⁻¹ (121 $ t⁻¹) for MP, 1446 $ ha⁻¹ (131 $ t⁻¹) for CP, 1380 $ ha⁻¹ (128 $ t⁻¹) for ST, and 1334 $ ha⁻¹ (112 $ t⁻¹) for NT system. The economic indices for each tillage system were computed. Our results showed that eliminating those negative products in corn production can increase farmers' net benefit by 200 $ ha⁻¹. Global warming potential, acidification potential, eutrophication potential, ozone depletion potential, and photochemical ozone creation were selected to reflect the environmental impact associated with corn production in each tillage system. From an environmental standpoint, NT and MP performed much better than CP and ST. In three important impact categories (i.e., global warming potential, acidification, and eutrophication potential) MP, and in the other two impact categories (i.e., photochemical ozone creation potential and ozone depletion potential) NT system performed best among all tillage systems. It can be concluded that NT showed the best performance in terms of energy, economic and environmental indicators for corn production followed by MP system.