Effect of pyrochar and hydrochar amendments on the mineralization of the herbicide isoproturon in an agricultural soil

摘要

Carbon (C)-rich, solid products from pyrolysis (pyrochars) and hydrothermal carbonization (HTC, hydrochars) are expected to reduce the bioavailability and bioaccessibility of pesticides as side effect of soil addition. To compare effects of different feedstocks (digestate, miscanthus, woodchips) and production processes (pyrolysis at 750 degrees C, HTC at 200 degrees C and 250 degrees C), C-14-labeled isoproturon (IPU) was applied at 0.75 kg ha(-1) to loamy sand amended either with 0.5% or 5% pyrochars or hydrochars, which was then incubated for 50 d. Mineralization of IPU was measured as C-14-CO2 released from soil-char composites. Pore-water and methanol extractable C-14-IPU was quantified as well as non-extractable C-14-residues (NER). Furthermore, C mineralization of pyrochars, hydrochars and feedstocks was studied to assess the relationship between IPU bioaccessibility and char decomposability.