The changes in biochar properties and sorption capacities after being cultured with wheat for 3 months.

Biochars that were produced from pig manure at three different temperatures were amended to sand and cropped with wheat to examine the effect of wheat roots on biochar properties and its sorption capacity. After being aged with wheat roots for three months, the biochar samples showed significant changes in their physicochemical properties, which depended on biochar types and their distances from the roots. In general, the ash content and micropores decreased and the polarity increased after root aging. The changes in the biochar properties in turn affected biochar sorption capacities. The sorption of atrazine and phenanthrene by the biochar that was produced at 300 °C (BC300) both increased by different extents after aging, significantly decreased for BC700, and there were little changes for BC500. The complex changes were due to the different dominant sorption mechanisms for different biochars and different chemicals. For BC700, hydrophobic partition and pore-filling were the main processes, especially for phenanthrene, whereas for BC300, polar interactions dominated.