Biochar as a local lever to reconnect topsoil and sub-soil hydrological and biological functions in degraded soils

Soils with low organic matter content and long-term structural degradation are widespread in Tunisian agricultural systems, resulting in poor water infiltration, weak biological activity and limited exploitation of the soil profile by crops. Locally produced biochar was introduced as a practical amendment to restore hydrological and biological functions across both topsoil and sub-soil. Biochar is incorporated into the cultivated layer at moderate application rates compatible with farm practices. When used as an amendment, biochar improves nutrient retention and fertilizer efficiency, reducing losses while supporting gradual soil regeneration.