Solubility (Ksp), adsorption (Koc), time for 50% decomposition (T1/2) and lethal dose-50 (LD-50) for pesticides used in two background and three beef-finishing systems of eastern Uruguay

Table 7. Solubility (Ksp), adsorption (Koc), time for 50% decomposition (T1/2) and lethal dose-50 (LD-50) for pesticides used in two background and three beef-finishing systems of eastern Uruguay. Values used to calculate the pesticide contamination risk (PPDB 2009). 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7 乌拉圭东部两种背景体系与三种肉牛育肥系统中所用农药的溶解度（溶度积Ksp）、吸附系数（Koc）、50%降解时间（T₁/₂）以及半数致死剂量（LD₅₀），相关数值用于计算农药污染风险（PPDB 2009）。摘要 碳足迹是衡量粮食生产对气候变化贡献的关键指标，其全球重要性与日俱增。尽管碳足迹已被用作评估生产体系可持续性的指标，但它未纳入诸多在局地尺度更具相关性的生物物理环境维度，例如土壤侵蚀、养分失衡与农药污染。本研究针对乌拉圭境内5个集约化程度逐步提升的实际肉牛背景育肥体系，估算了其碳足迹、化石燃料能源消耗、土壤侵蚀量、养分失衡情况以及农药污染风险；这些体系为放牧牧场（grazing rangelands, RL）、播种牧草牧场（seeded pastures, SP）与育肥圈舍（feedlot, FL）的组合模式。碳足迹从16.7（RL–RL）kg CO₂当量·kg 体重⁻¹（body weight, BW；‘eq’即当量）降至6.9（SP–FL）kg CO₂当量·kg 体重⁻¹。RL–RL体系的能源消耗为0，SP–FL体系则升至17.3 MJ·kg BW⁻¹。土壤侵蚀量介于7.7（RL–RL）kg 土壤·kg BW⁻¹至14.8（SP–FL）kg 土壤·kg BW⁻¹之间。氮、磷养分平衡在播种牧草牧场与育肥圈舍体系中呈现盈余，而RL–RL体系则呈亏缺。RL–RL体系的农药污染风险为0，SP–FL体系则升至21.2。在本研究所涵盖的输入使用量逐步提升的体系范围内，全球与局地环境问题之间呈现出权衡关系。研究结果表明，评估畜牧生产体系的可持续性需要采用多指标体系。