Abstract
The study analyzed labile and stable SOC fractions in different land use systems in the Colombian Amazon. The research included cacao-based Agroforestry Systems (cAFS), full-sun cocoa plantations, forests, and pastures, using a factorial design with land use and soil depth as factors. Land use significantly affected carbon fractions, explaining 51% of variance ( P −1 ) and lowest in Pasture (2.76 g C kg −1 ). For humic acids, full-sun cacao showed the highest values (9.55 g C kg −1 ) followed by Capiron (7.75 g C kg −1 ). Total Humic Extract was maximum in full-sun cacao (27.68 g C kg −1 ) and minimum in Pasture (18.99 g C kg −1 ). The polymerization index was higher in Pasture (1.87) and full-sun cacao (1.46). The degree of humification was highest in full-sun cacao (64.78%), while the humification ratio showed maximum values in full-sun cacao (84.9%) and minimum in Forest (36.86%). These patterns generally persisted at deeper soil layers, demonstrating the potential of cAFS as a sustainable alternative for land use and carbon sequestration.