Relationship between soil organic matter fractions and cover plants in Olive post planting

Abstract Erosion is the main cause of soil degradation, compromising soil productivity and sustainability. As soil organic matter (SOM) is a key indicator of quality, this study aimed to evaluate the effect of different olive tree managements on SOM and its soil fractions in soil (Inceptisol) and erosion sediments. Five treatments were installed: bare soil, olive cultivation in bare soil, olive tree intercropped with jack bean, olive tree intercropped with pearl millet, and olive tree cultivated with spontaneous vegetation; a contiguous area of native vegetation was used as reference. Carbon in soil and sediment were determined by wet oxidation with external heating, while the fractionation of SOM was performed based on granulometry. The Carbon Management Index (CMI) was determined by the proportions of SOM fractions. The results indicated that SOM associated with minerals is the most present in soil and sediment erosion, regardless of the adopted management. Results on CMI showed that the systems olive tree intercropped with pearl millet or with spontaneous vegetation are the most favorable to increase the carbon stock in the soil.