Grazing intensities versus stocking methods: Implications for greenhouse gas emissions in integrated crop-livestock systems.
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Predicted global warming of 2.7 ◦C by the end of the century threatens the Paris Agreement targets, underscoring the need for improved food-system management to increase productivity while reducing greenhouse gas (GHG) emissions. Integrated crop–livestock systems (ICLS) represent a promising pathway, although important uncertainties remain regarding the balance between carbon dioxide (CO2) removal and methane (CH4) and nitrous oxide (N2O) emissions. Therefore, this study assessed how stocking methods (continuous vs. rotational) and grazing intensities (moderate vs. low) affect the global warming potential (GWP) and GHG emission intensity (GHGI) of ICLS relative to ungrazed areas. The experiment combined soybean [Glycine max (L.) Merr.] and maize (Zea mays L.) in rotation with Italian ryegrass (Lolium multiflorum Lam.) grazed by sheep. Over three years, GWP (kg CO2eq ha 1 yr 1) was quantified based on net CO2, N2O, and CH4 emissions, together with the energy costs of farming operations. ICLS produced more crude protein (grain plus meat) than ungrazed areas (842.4 ±53.2 vs. 586.6 ±20.0 kg ha 1 yr 1; P <0.01), corresponding to a 44 % increase. However, ICLS was a net GHG source (+1786.5 kg CO2-eq ha 1 yr 1; P <0.01), with sheep enteric CH4 emission accounting for approximately 49 % of total GWP. Moderate grazing intensity increased GHGI relative to low grazing intensity (6.19 ±0.27 vs. 4.47 ± 0.32 kg CO2-eq kg 1 crude protein yr 1; P <0.01) across stocking methods. Overall, grazing intensity had a greater influence on GHGI than stocking method, identifying grazing intensity as the primary lever for emission intensity control in ICLS. Despite enteric CH4 emissions, these findings highlight that ICLS can be optimized through management to reconcile productivity and climate mitigation.
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Mudança Climática, Efeito Estufa, Conservação do Solo, Conservação, Climate change, Integrated agricultural systems, Greenhouse gas emissions, Grazing management, Carbon sequestration