Ṇitrogen footprint of Korean beef cattle farms: Scenarios toward more sustainable production

Abstract

AbstractNitrogen (N) lost during beef cattle production accompanies various environmental risks and has become a rising concern among agricultural stakeholders. The objective of this study was to quantify the N footprint of producing Hanwoo beef cattle, which is a Korean indigenous breed of cattle, in Korea at the farm gate through a life cycle assessment approach. Field surveys were conducted on 106 farms across 9 provinces to identify regional distinctions in farming systems and evaluate total N losses from beef production. N losses were calculated using emission factors from the refined IPCC guidelines, which were then expressed as N footprint (g N/kg of live body weight (LBW)). Uncertainty and sensitivity analyses were deployed to evaluate the precision of the results and identify factors that contributed to the output. The N footprint averaged 132.7(± 61.8) g N/kg LBW and varied between provinces according to animal categories, manure management systems, land use and fertilizer application rates. Volatilization was the highest contributing factor, followed by leaching and denitrification, each representing 68.5, 21.4, and 10.1 percent of the N footprint, respectively. The uncertainty of the result was found to be 46.6 percent and was highly associated with emission factor uncertainties. We devised five mitigation scenarios that are cost effective and do not penalize productivity and evaluated their capacity for reducing N footprint: (i) dietary modifications to decrease animal N excretion rate; (ii) microorganism additives to reduce volatilization from housing; (iii) manure storages recycling manure within the farm to replace synthetic fertilizers; (iv) distributing biochar to the field after fertilizer application to curtail losses from crop production; (v) combination of i, ii, iii, and iv. Combining these scenarios demonstrated the potential to reduce 12.1 percent of the total N footprint. The extents of mitigation scenarios varied across provinces (ranging from 5.2 to 21.7 percent) and were shown to be contingent on feeding practices and type of crop cultivated. Overall, our study provides a national metric that can be utilized to communicate the environmental impacts of Korean beef production. The analyses indicate that more precise results could be achieved with future endeavors towards developing country-specific emission factors. The mitigation potentials of the presented scenarios propose possibilities for feasible and sustainable beef production in Korea.