Assessment of long-lived Carbon permanence in agricultural soil: Unearthing 15 years-old biochar from long-term field experiment in vineyard

• Biochar has been unearthed for the first time from very long-term biochar experiment in vineyard. • This was among the longest biochar experiments under actual cultivation conditions, lasting 15 years. • Procedure to recover biochar from soil and exogenous matter, and characterizez it vs original biochar, was applied. • Exogeneous inorganic and organic matter was quantified, as well as intertinite and semi-inertinite by Random Reflectance. • Long-term permanence of macerals was assessed for possible inclusion in permanent carbon removal category