Switchgrass Productivity Is Not Altered By Biochar Addition to Quebec Soils.

Biochar has been reported to improve crop yields however, the magnitude of these effects is variable depending on biochar and soil properties, climate and crop.  Furthermore, biochar soil amendments can render biofuel production systems carbon (C)-neutral by sequestering C from the atmosphere into the soil.  Because of the recalcitrant nature of biochar, this C will not be released into the atmosphere in the short term.  In a switchgrass (SG) bioenergy system, applying biochar to soil could maximize feedstock yields and simultaneously minimize C emissions.  This set of field experiments was conducted to examine the impact of biochar on SG productivity under field conditions.

Two field trials were conducted in Sainte-Anne-de-Bellevue, Quebec, Canada during the 2010, 2011 and 2012 growing seasons using a softwood biochar produced by slow pyrolysis. The first experiment hypothesized that biochar effects on SG productivity would vary based on soil type.  In this experiment, biochar was applied at rates of 0, 10 and 20 tonnes ha^-1 on two field sites, one sandy soil and one loam soil. The second experiment hypothesized that biochar effects on SG productivity would vary depending on timing of application. This experiment used the same rates as above, with an additional rate of 40 tonnes ha^-1.  Two timing treatments were compared: in the first treatment all the biochar was applied prior to stand establishment, in the second treatment the biochar application was split between the first and second growing seasons (half was applied in spring prior to the establishment year and half was applied the following spring).  While some small differences were observed in SG productivity in its establishment year, these differences did not persist into the following growing seasons.  Detailed results based on soil type and timing of application will be presented.