Biochar is a carbon rich output that is produced by pyrolysis of biomass. Pyrolysis is heating biomass in a reduced oxygen environment to separate the volatiles and leave behind a carbon rich product. Biochar has many uses.
It all depends on how it’s produced.
Most BBQ charcoals are made from materials that have not been completely pyrolysed, leaving tars and creosotes to lend their smoky flavour to BBQ meals. These volatiles may harm plants and animals if applied to soils.
Good quality biochar is free of volatiles and has no taste or smell. It is also brittle, so you can crush it between your fingers without any oily residue.
Finally, biochar can be made from any biomass, but BBQ charcoal is usually made from woody materials.
Biochar has a wide range of applications. Most commonly, farmers, horticulturists, and home gardeners use biochar as a soil amendment.
Biochar can contribute to animal care, carbon sequestration, water (and sewage) filtration and treatment, and more.
Please see follow this link for more detailed information.
The fertiliser value of a biochar itself depends on the biomass it was produced from. Talk to suppliers of NZ made biochar about the fertiliser value of their biochars.
Biochar has also been shown to improve plant-available nutrients in the soil through holding soluble fertilisers and water near plant roots for longer, and increasing the soil’s microbial nutrient cycling capacity
There are many ways to make biochar using all sorts of equipment – from a biscuit/milo tin scale to an industrial scale. All of them involve heat. Check out some small scale plans here and this video demonstration for a back yard demonstration.
Contact BNNZ to arrange a demonstration for your community. There may be a fee to cover costs.
Contact BNNZ about technologies for larger scale applications.
Contact BNNZ to arrange a demonstration. There may be a fee to cover costs.
We have evidence in the form of well-developed, fertile soils in regions such as the US midwest, the Russian and Ukrainian grain belt, and the Argentine pampas to show us how the presence of pyrogenic carbon has helped create some of the most productive growing conditions on the planet. We have the record of deliberate addition of charred matter which turned parts of the highly leached rainforest soils of the Amazon into terrapreta, whose abundance allowed settled agriculture to develop and sustain a thriving culture. These case studies extend thousands of years into the past and provide a sound basis for a call to produce and incorporate biochar into productive landscapes over the long term. Even if the secondary benefits were deemed unimpressive, the carbon sequestration potential of a large-scale biochar application programme merits priority treatment as part of New Zealand’s climate mitigation strategy.
Laboratory simulations of accelerated weathering on samples of biochar show losses at longer timescales, but the majority of the bound carbon can be expected to remain stable for decades at the very least, and centuries in the median prospect. Radiocarbon dating of the pyrogenic carbon fraction in soils has yielded ages of over 2,500 years in the terra preta soils of the Amazon, 7,000 in the US Midwest, and 12,000 in Russia.
Integrating carbon crops can work well in an existing farm setting, as many of the plants which are suitable can be grown in marginal areas which are the least fit for grazing or cultivation. Annual rotations of plants such as hemp can provide benefits through the root mass left in the soil, and a crop such as maize could provide a dual yield if the grain were harvested and the stover used for biochar. Marginal plantings of coppice forestry along drains and raceways would help mitigate some nutrient loss during the growing season, and offer a recurring harvest of high-carbon feedstock.
The sum of these three streams would account for 14.4 MT CO 2 e annually, nearly one fifth of our gross GHG emissions of 80.9 MT CO2e.
Also, instead of planting ever increasing swathes of Pinus radiata on sheep and beef country and crossing fingers against the changing climate and the increasing risk of wildfire, we could instead be growng low-input carbon crops such as coppicing forestry, switchgrass, miscanthus, or hemp. A commitment of just 50,000 ha to carbon crops yielding 20T/ha pa would translate to 1.9 MT CO 2 e each year as well as provide jobs for the regions currently facing the prospect of being turned into “pine deserts” by wholesale forestry conversion.
The labile fraction of soil carbon is most susceptible to land use change, poor management, and adverse climate driven events, and can be lost in quantity as a result of such simple activities as tilling, overgrazing, and fertiliser over-application, at timescales as short as days or weeks. The humic fraction is durable, degrading only slowly in the presence of specific microbial activity. Biochar is solely at risk from rapid destruction through burning, and once emplaced in soil (or water) it is unlikely to be present in sufficient ratios to support combustion except in the most extreme scenarios.
© 2021 Biochar Network NZ
BNNZ acknowledges the generous support of Soil Conditioner Products Ltd, NZ Biochar Ltd, Black Moa Biochar, and Slow Farm Ltd