Carbon dynamics in different soil types amended with pig slurry, pig manure and its biochar

Resumen

Determining the structure and components of soil and soil organic matter is very important in terms of sustainableagriculture and forestry and greenhouse gases emissions. Organic management can increase labile C and N in theshort-term, and total soil C and N in the long-term, but less is known about how management practices may affectsoil organic C (SOC)quality and stability. Methods to improve the management of livestock slurries to reduce theenvironmental impact and carbon losses are gaining importance. There is a need to find the best wastes treatmentwhich enhances soil fertility but also carbon sequestration, to mitigate the effects of global warming.The objective of this study was to assess the short-term changes in SOC pools, using raw pig slurry, the solidphase of pig slurry, and its biochar as amendment in different soil types (Regosol, Luvisol and Kastanozem).The three different amendments were applied at 5 g C kg-1 soil. An unamended soil for each type was usedas control. Soils were incubated in triplicate for 60 days at 25ºC and at 55% of their water holding capacity.Samples were sampled to monitor the evolution of soil organic and inorganic carbon, recalcitrant carbon, solublecarbon, carbon mineralization, SOC thermal distribution (thermogravimetric analysis - differential scanningcalorimetry - quadrupole mass spectrometry), and characterization of functional groups (Fourier transforminfrared spectroscopy (FTIR)). Results showed that soils amended with raw pig slurry and the solid phase ofthe slurry showed higher values of soluble carbon, and higher carbon mineralization rates compared to biocharapplication, which showed values similar to controls. SOC increased at the end of incubation with biochar and thesolid phase of the slurry applications in Kastanozem and Regosol.