Improving greenhouse gas emissions intensities of subtropical and tropical beef farming systems using Leucaena leucocephala

Leucaena leucocephala (leucaena) is a perennial legume shrub of subtropical regions that has forage characteristics favourable for livestock production, often delivering ruminant liveweight gains that are superior to most other forage systems. Recent work suggests that leucaena mitigates ruminant enteric methane emissions, implying that the shrub may also reduce greenhouse gas (GHG) emissions at the whole farm level. However, the high crude protein content of leucaena relative to endemic grasses can increase livestock urine nitrogen concentration and may increase soil nitrous oxide emissions, potentially offsetting benefits of enteric methane mitigation.