Farm scale modelling of greenhouse gas emissions from semi-intensive suckler cow beef production

Abstract

A whole-farm model, HolosNorBeef was developed to estimate net greenhouse gas (GHG) emissions from suckler beef production systems in Norway. The model considers direct emissions of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) from on-farm livestock production including soil carbon (C) changes, and indirect N2O and CO2 emissions associated with leaching, volatilization and inputs used on the farm. The emission intensities from average beef cattle farms in Norway was estimated by considering typical herds of British and Continental breeds located in two different regions, flatlands and mountains, with different resources and quality of feed available. The flatlands was located at a low altitude in an area suitable for grain production and mountains was located at higher altitude in a mountainous area not suitable for grain production. The estimated emission intensities were 29.5 and 32.0 kg CO2 equivalents (eq) kg‐1 carcass for the British breeds and 27.5 and 29.6 kg CO2 eq kg‐1 carcass for the Continental breeds, for flatlands and mountains, respectively. Enteric CH4 was the largest source accounting for 44–48% of total GHG emissions. Nitrous oxide from manure and soil was the second largest source accounting for, on average, 21% of the total emissions. Carbon sequestration reduced the emission intensities by 3% on average. When excluding soil C the difference between locations decreased in terms of GHG emission intensity, indicating that inclusion of soil C change is important when calculating emission intensities, especially when production of feed and use of pasture are included.