Cultivated soils in the arid regions of the Middle East and North Africa present low fertility and productivity due to low organic matter stocks. Date palm residues are an abundant resource in these regions and only a minor part is recovered in oasian agroecosystems. Recycling organic residues in agriculture via composting or pyrolysis transformation processes may increase soil organic matter (SOM) and nutrient stocks. The aim of this study was to assess the biodegradability of biochar and compost in a poor cultivated sandy soil sampled in an oasis from southern Tunisia. Carbon mineralization dynamic was monitored over 112 days by alkali absorption of CO2 released at regular intervals during incubation experiments at 25°C. Soils were amended with compost and/or biochar with a fixed dose for compost (3% by weight) and two doses for biochar (0.75 and 1.5%). Rock-Eval® analysis was used to examine the thermal stability of SOM and organic amendments. Apparent mineralized organic carbon fraction of the compost was 16.7% after 112 days with a relatively constant decomposition rate. However, low thermal stability of the initial pure compost revealed by the Rock-Eval analyses highlighted the poor stabilization of the organic matter during composting process. This has been attributed to the artisanal nature of compost production, and particularly the use of poor quality irrigation water, which cause salts accumulation in the final product. Biochar addition to the soil did not significantly increase C mineralization. Its recalcitrant C pool was > 97%, indicating a low labile fraction. A model was constructed by combining the kinetic parameters of compost and biochar calculated from carbon mineralization data. The expected and the measured values in soil amended with compost and biochar were similar, indicating no apparent priming effect. The organic amendments showed a high amending potential in the selected OM-poor soil, especially biochar.