Greenhouse gas emissions of African Stargrass-based dairy systems under organic or inorganic fertilization regimes

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Background Properly managed livestock operations play a significant role in reducing greenhouse gas emissions in agriculture. We assessed the effects of applying organic and inorganic fertilizers to African Stargrass pastures on greenhouse gas emissions. Methods The study was conducted at the Dairy Research Station of the University of Costa Rica (May–November 2019 and 2021). Six fertilization treatments were evaluated under a randomized complete block design. Greenhouse gases included methane (CH4) and carbon dioxide (CO 2 ) fluxes measured at ground level using static chambers, nitrous oxide (N 2 O) emissions calculated using IPCC factors, and simulated enteric methane emissions using the LIFE-SIM model, based on forage biomass and nutritive value. Results CO 2 emissions were numerically similar ( p > 0.05), with greater values in sulfur-coated urea (15,114 kg ha −1 ) and lower in Azospirillum (13,799 kg ha −1 ). Soil CH4 was significantly greater ( p < 0.05) in ammonium nitrate (3.30 kg ha −1 ) with respect to sulfur-coated urea (1.37 kg ha −1 ). Emission intensity was numerically greater in slurry (2.58 kg CO 2 eq kg −1 DM), and lower values in sulfur-coated urea (1.56 kg CO 2 eq kg −1 DM). Conclusions Although some significant differences were found for soil emissions, both CH 4 and N 2 O were a small fraction of the emissions when totalized as CO 2 eq. The type of fertilizer applied to African Stargrass pastures influenced the emission intensity as a result of their impact on grass productivity. This study depicted the impact of soil and enteric emissions in pastures, providing an integrated approach for mitigation strategies to tackle emissions under tropical conditions.