Nitrous Oxide Emissions in Black Oat-Corn Succession Fertilized with Pig Slurry and Swine Manure Compost Supplemented with Mineral Fertilization

Manure from pig farming has an agronomic value and it is often used for fertilization. However, as manure has unbalanced amounts of nutrients such as N and C, it contributes to increased emissions of N₂O to the atmosphere. This study evaluated N₂O emissions in soil with treated with pig slurry (PS) and swine manure compost (SMC). The study was conducted from 2018 to 2019 in an experiment, in southern Brazil. The system was minimal tillage with black oat and corn. The treatments were control, swine manure compost + mineral fertilization (SMC + MF) and pig slurry + mineral fertilization (PS + MF). The measurements of N₂O fluxes were carried out throughout the crop cycle with static chambers. Cumulative emission values, as well as crop yield and emission values per ton produced were compared with one another by the LSD test (p < 0.05). In general, the largest fluxes of N₂O were found in soil fertilized with PS + MF. There were intense emission peaks after PS application. Cumulative annual emissions of N₂O differed among treatments. Values ranged from 0.62 to 3.15 kg ha⁻¹ N₂O-N in control and PS + MF soil, respectively, representing a relative increase of 508%. The soil with SMC + MF showed a similar behavior to the control, with a cumulative annual emission of 0.65 kg ha⁻¹ N₂O-N. The soil with SMC helped to significantly reduce N₂O emissions in 4.8 times compared to the one with PS. This result highlights the use of compost as an alternative strategy to slurry to reduce N₂O emissions.