An increasing body of scientific research records gains in biomass for trees planted with biochar added to their planting pits. Put simply, larger, more vigorous trees result, particularly if the biochar is charged with compost teas or similar (allowing borage or nettle to soak thoroughly in water for a few weeks will do a fantastic job).
However, additional benefits to incorporating biochar in soils accrue from improved structure to carbon storage and increased porosity, as soils are opened up and compaction levels reduced. Fields selected for tree planting can often have impacts from heavy traffic and vehicle movements to address, which should be considered before any tree planting starts.
At the Agroforestry show, we also trialled a biochar retort, in partnership with Luke Breedon from Slate Hill Charcoal. Fresh biochar was produced in very short periods of time, from hedgerow trimmings, crop residues and other arisings. The retort itself is portable, easy to use and very efficient, so offers a great opportunity to demonstrate how biochar can be made onsite and incorporated directly into soils or inoculated with those compost teas, then added to tree planting pits for agroforestry systems.
Author:
Ed Bonn – Farm Environment Adviser