Greenhouse gas emissions of five background-finishing beef systems of eastern Uruguay and previous published results

Table 9. 
Greenhouse gas emissions of five background-finishing beef systems of eastern Uruguay and previous published results. (Note: RL: rangeland systems; SP: seeded pasture systems; FL: feedlot systems.)
Abstract Carbon footprint is a key indicator of the contribution of food production to climate change and its importance is increasing worldwide. Although it has been used as a sustainability index for assessing production systems, it does not take into account many other biophysical environmental dimensions more relevant at the local scale, such as soil erosion, nutrient imbalance, and pesticide contamination. We estimated carbon footprint, fossil fuel energy use, soil erosion, nutrient imbalance, and risk of pesticide contamination for five real beef background-finishing systems with increasing levels of intensification in Uruguay, which were combinations of grazing rangelands (RL), seeded pastures (SP), and confined in feedlot (FL). Carbon footprint decreased from 16.7 (RL–RL) to 6.9 kg (SP–FL) CO2 eq kg body weight−1 (BW; 'eq': equivalent). Energy use was zero for RL–RL and increased up to 17.3 MJ kg BW−1 for SP–FL. Soil erosion values varied from 7.7 (RL–RL) to 14.8 kg of soil kg BW−1 (SP–FL). Nitrogen and phosphorus nutrient balances showed surpluses for systems with seeded pastures and feedlots while RL–RL was deficient. Pesticide contamination risk was zero for RL–RL, and increased up to 21.2 for SP–FL. For the range of systems studied with increasing use of inputs, trade-offs were observed between global and local environmental problems. These results demonstrate that several indicators are needed to evaluate the sustainability of livestock production systems.

表9. 乌拉圭东部五种背景肉牛养殖系统的温室气体排放量及先前发表的结果。（注：RL：牧场系统；SP：播种草地系统；FL：饲料场系统。）摘要碳足迹是衡量食品生产对气候变化贡献的关键指标，其在全球范围内的重要性日益凸显。尽管它已被用作评估生产系统的可持续性指标，但它并未考虑到许多在局部尺度上更为相关的生物物理环境维度，例如土壤侵蚀、养分失衡和农药污染。我们对乌拉圭五种实际肉牛背景肉牛系统进行了碳足迹、化石燃料能源消耗、土壤侵蚀、养分失衡和农药污染风险的估算，这些系统随着集约化程度的提高而组合了放牧牧场（RL）、播种草地（SP）和围栏饲养（FL）。碳足迹从16.7 kg（RL-RL）降至6.9 kg CO2 eq kg 体重-1（BW；'eq'：当量）。能源消耗对于RL-RL为零，而对于SP-FL则增至17.3 MJ kg 体重-1。土壤侵蚀值从7.7 kg（RL-RL）至14.8 kg 土壤 kg 体重-1（SP-FL）不等。氮和磷养分平衡显示，播种草地和饲料场的系统存在盈余，而RL-RL则表现为不足。农药污染风险对于RL-RL为零，而对于SP-FL则增至21.2。在研究了输入使用量不断增加的系统范围内，观察到全球和局部环境问题之间的权衡。这些结果证明了评估畜牧业生产系统可持续性需要多个指标。