Anatomy of a field trial: Wood-based biochar and compost influences a Pacific Northwest soil

Biochar land application research in elevated rainfall areas (980 millimeters of annual rainfall) of the U.S. Pacific Northwest is lacking. A proof-of-concept field study examined the effects of spruce-pine-fir wood chip biochar (slow pyrolysis; 450-500 degrees Celsius; 35 megagrams per hectare), dairy manure compost (105 megagrams per hectare), compost + biochar (35 and 105 megagrams per hectare, respectively), and a control (no biochar or compost) on glacially altered soil (sandy or loamy skeletal, isotonic, mesic humic or aquic Dystroxerepts) chemical properties and growth characteristics of vetch and sweet corn over a growing season. In-season liming (5.4 megagrams per hectare) occurred to raise the soil pH for adequate crop growth. Biochar, alone or applied with compost, maintained a greater amount of soil organic carbon and, when combined with lime, acted more effectively than control conditions. Biochar and compost + biochar treatments reduced plant-available zinc and copper concentrations, although the concentrations were still an order of magnitude greater than those considered minimal for crop growth. There was no difference in vetch or corn yield among treatments. However, the compost + biochar treatment increased vetch total nitrogen and magnesium content, as well as corn copper content. Overall observations suggest that co-applying biochar with an organically-rich material like compost could be beneficial without compromising environmental quality