CARBON STORAGE AND STABILITY OF SOIL ORGANIC MATTER IN A COFFEE AGROECOSYSTEM IN SIERRA SUR DE OAXACA, MEXICO

Abstract

We evaluated the ability of the soils in a shade coffee agroecosystem under different handling conditions to accumulate stable forms of carbon in the Sierra Sur of Oaxaca, for this we quantify the soil carbon store and performed the isolation and chemical characterization of soil organic matter by chemical fractionation, UV-visible and infrared spectroscopy in the first 40 cm depth. Results showed no significant differences in carbon stores between handling conditions, reaching mean values 150 Mg C ha-1. Humification patterns are consistent for all soils and indicate that over 50% of soil organic matter found in the insolubilization humins and between 15 and 20% are humic acids. This fraction, presumably the most stable, is made up of molecules whose aromatic and maturation has a positive relationship with increasing altitude and clay content. According to the above confirms the ability of shade-coffee agroecosystems to accumulate high carbon content associated with stable forms of soil mineral fraction.