Biochar and macadamia shell

The by-product macadamia shell from macadamia agroforestry can be used as a solid fuel in a suitable cookstove to produce very high quality biochar.

The uses of biochar are very extensive including significant enhancement of soil, especially where intensive farming occurs and where soil quality and fertility may have been reduced over many years of farming. Smallholder macadamia agroforestry and its by-products can therefore be very beneficial for soil enhancement as well as provision of a nutritious food.

NMT have been investigating cookstove design and use for biochar production and soil enhancement. Having seen a working cookstove design from Costa Rica NMT has been investigating the building and use of such a cookstove in a smallholder context in Malawi.

External links about how effective biochar is for soil enhancement:
Wikipedia article
Researchgate article
Researchgate article - use in Nepal.
 
In the UK biochar has recently been produced by simple burning of excess poor quality wood in a metal drum incinerator which could have been used to produce a large volume of boiling water, however in this case was just used to produce a reasonable quantity of biochar which was then cooled with water and mixed with soil ready to be used for soil enhancement. This is shown in the following pictures.


Burning excess, poor quality wood in incinerator. Efficiency is low to medium, due to the open top. Sadly in this test the energy was not used to boil water.
 
The NMT cookstove design with the restricted lid and tin can flue is much more efficient, producing a high quality gasified flame, when properly lit.

A reasonable volume of carbon/biochar residue collected at the bottom of the drum, where a lower oxygen burn produces the biochar from the solid fuel.
 

Soil enhanced with wet biochar ready to significantly improve soil quality and fertility.
The biochar locks carbon for a near permanent length of time!

Sweet corn and squash plants ready to be planted in the biochar enhanced soil bed.

Website by Simon Woolverton