Response of water-biochar interactions to physical and biochemical aging.

Biochar aging may affect the interactions of biochar with water and thus its performance as soil amendment; yet the specific mechanisms underlying these effects are poorly understood. By means of FTIR, N adsorption, Hg intrusion porosimetry, thermogravimetric analysis, C solid state nuclear magnetic resonance (NMR) and H NMR relaxometry, we investigated changes in the chemistry and structure of biochar as well as its interaction with water after biochar aging, both physical (simulated by ball-milling) and biochemical (simulated by co-composting). Three different porosities of biochar were examined: <5 nm, 1 μm and 10 μm diameter sizes.