Abstract

Amending soil with biochar (BC) can change the sorption properties of soil. However, much of this concern is based on studies from BC produced from wood and crop residues. Since BC can be made from a wide range of feedstock, it is important to cover all the aspects of feedstock applied as the soil amendments. Six types of feedstock were examined in this study, including a compost, a papermill waste, a leguminous biomass, two bioenergy crop biomass (switchgrass pellet and 3-years-old shrub willow wood chip), and an oak wood biomass. The raw feedstock was pyrolyzed at 300oC and 500oC, respectively. We investigated how feedstock and pyrolytic temperature affect diron sorption and used a bioassay of the BC amendments in a loamy soil to test the change of herbicide efficacy. With the pyolytic temperature increasing, the diuron sorption rate increased. The 300oC BCs developed a slightly higher diuron sorption rate than the raw materials, and a considerable enhancement in diuron sorption rate was observed for all 500oC BCs. Similar to the sorption capacity of the herbicide, the sequence in reducing herbicide efficacy was 500oC BC > 300oC BC > raw material. Hence, our results suggest that the effect of herbicide effectiveness from BC amendments can be reduced when raw material is converted into BC, especially the BC produced at the high temperature (>500°C).