Nitrogen fertilizer value of sewage sludge co-composts Khadija Bousselhaj, Saïd Fars, Abderrahmane Laghmari, Ahmed Nejmeddine, Naaila Ouazzani and Claudio Ciavatta Agronomie, 24 8 (2004) 487-492 DOI: 10.1051/agro:2004045