GREENHOUSE gas emissions in coffee plantations on a bauxite-mined soil undergoing reclamation: Management fertilizer and cover crop

Alternatives that control the impacts on the soil and the environment are important for reusing agricultural lands after bauxite mining. In this study, we evaluated the effects of organic and mineral fertilization with or without cover crops on soil organic carbon (SOC) pools, coffee (Coffea arabica) bean yield, and soil greenhouse gas (GHG) emissions in the reestablishment of coffee plantations on a bauxite-mined soil undergoing reclamation. The experiment consisted of a split-plot design with four replicates. The main plot received three types of fertilization: nonfertilization (NF), mineral fertilization (MF), and poultry litter (PL). In subplots, an area without cover crops (-CC) and another with Urochloa ruziziensis (+CC) were considered. GHG fluxes (CO₂, CH₄ and N₂O) were measured over eight months, and the accumulated fluxes for each GHG, global warming potential, carbon management index, and soil C-CO₂ relative emissions were calculated at the end of the measurements. The soil organic carbon (SOC), easily oxidable carbon (KMnO₄-C) contents and coffee bean yield were also measured in two seasons. We found that Urochloa ruziziensis between the coffee plantations provided lower relative CO₂ emissions. CO₂ and N₂O emissions were higher in soils with coffee plantations fertilized with PL. The CH₄ efflux behavior between the treatments was similar. The accumulated soil N₂O flux, with the poultry litter increases by approximately 87 % and 98 % in relation to MF and NF treatments, respectively. The accumulated efflux of CH₄ in the soil of coffee trees planted -CC and MF treatments was 75.8 % higher than that +CC and MF treatments. The -CC and MF treatments contributed 31 % more to the relative CO₂ emissions. On the other hand, the combination of U. ruziziensis and PL application provided a total SOC 23.80 % higher than that in the -CC areas. The KMnO₄-C content and carbon management index were also higher in treatments with +CC between the coffee plantations. However, the highest production of coffee beans was with PL application (46 sc ha⁻¹) followed by MF (25 sc ha⁻¹) in the -CC. Our study presents evidence that the combined use of poultry litter and U. ruziziensis allows the recovery of SOC following bauxite mining. Poultry litter without vegetation cover contributes to higher production; however, it provides greater accumulated efflux and GHG emissions. Our findings highlight the importance of adequate soil management in coffee plantations on a bauxite-mined soil undergoing reclamation.