Abstract
The use of biochar is an interesting alternative to control release of P in soil and efficient use by plants. In this study, a new-coated slow-release P was developed by coating triple superphosphate (TSP) using different biochars (BC) and carboxymethyl cellulose (CMC). This study employs an integrated lignocellulosic biorefinery methodology and circular bioeconomy concept, utilizing a cellulose derivative and biochar produced from macroalgal residues (BCA) and olive pomace (BCO). The study explores the impact of integrating these biochars into CMC matrix as coating materials. The findings demonstrated that the origin of biochar had an effect on the surface and mechanical attributes of the composites. Introducing biochar modified the mechanical proprieties, alongside an increase in the contact angle. However, the attrition of coated TSP seems to be high with high biochar content. An increase in water absorption was also observed with formulations containing more biochar. The release tests showed that the P release decreased up to 67 %, 78 % and 82 % within 30 days with CMC coatings in presence of BCO, BCV and BCA, respectively compared to 100 % with uncoated TSP fertilizer. However, no significant difference on P release was observed when varying the biochar content from 10 to 30 %.