Organic carbon fluxes using column leaching experiments in soil treated with pig slurry in SE Spain

In semi-arid climates, the management of pig slurry is very important, since it may cause an environmental problem, but on the other hand it has positive impacts such as high labile and organic carbon content. Leaching experiments were carried out to establish the mechanism of soil C dynamics using the raw pig slurry with legislated doses (LD) (170 kg ha(-1 )year(-1)) and the high doses (HD) (510 kg ha(-1 )year(-1)). Organic carbon (OC) content of the soil ranged between 6.81 and 15.50 tons OC ha(-1) at the beginning, which ranged between 11.39 and 26.26 tons OC ha(-1) at the end of the experiment and significantly increased with the HD, especially in the subsurface zone. Carbon lost from the soil respiration was similar to 0.01 ton C-CO2 month(-1 )ha(-1) in control and varied between 0.01 and 2.30 ton C-CO2 month(-1 )ha(-1) in LD, and 0.01 and 7.16 ton C-CO2 month(-1 )ha(-1) in HD, respectively. The losses of OC by leaching from dissolved organic carbon (DOC) were 0.15, 0.07, and 16.30% with LD, HD, and the control (CT), respectively. Dissolved OC content in leachates was lower in LD treatment than in HD treatment. The changes of OC from the beginning were between +15.85, +24.65, and -0.8% (+1.97, +3.15, and -0.11 ton OC ha(-1)) with LD, HD, and CT, respectively. Results suggest that the agronomic rate (LD) application could be considered as a fertilizer treatment in terms of soil C sequestration.