Friday, September 6, 2019

Making Biochar: Slash-and-Char Instead of Slash-and-Burn

As a side note for the not so distant future, replacing ‘slash-and-burn’ with ‘slash-and-char’ could be encouraged “thru the nascent carbon trading market that sponsors carbon sequestration projects and could supplement the subsistence farmer’s income while building up a more sustainable agriculture and slowing deforestation.”

Note: After reading about using ‘slash-and-char’ (that produces soil amending, crop boosting biochar) instead of ‘slash-and-burn’ (that leaves only ash), it’s obvious that slash-and-char is the desirable field clearing method. 
“It sequesters considerable quantities of carbon in the safest and most beneficial fashion, as opposite to the negative effects of the slash-and-burn. Switching to slash-and-char can sequester up to 50% of the carbon in a highly stable form.” 

There are two problems. One is the labor intensitivity of doing so (at least initially / in the long run though, it pays huge dividends), and the other is that biochar is NOT a fertilizer. Indeed, it’s like a sponge that retains organic matter, nutrients and moisture to prevent their loss. Fresh char made from cellulose first absorbs nutrients from the soil, then later begins releasing what it has kept from leeching away. It works best in acidic soils like tropical rainforests. The practice allows annual cultivation of the same fields, rather than slash-and-burn practices necessary to eke out crops on new land every few years. Given a stable location for agriculture and soils made fertile by char, a steady food supply is possible.

One big advantage with slash-and-char is that you’re not cutting down forests to produce char. You’re merely preventing the almost complete wastage of the biomass that slash-and-burn would have resulted in. 
[I do not support purposely raising, logging trees to create biochar.]
Search: wikipedia biochar

Though I haven’t made biochar ‘per se’, I had a lifetime of experience hand clearing and burning brush and trees in the monte of south Texas. While living on my ranch, I also burned our household trash — which I did using a pit. Burn trash, backfill with dirt from the new pit dug next to it, repeat. As I watch videos of biochar being made and in thinking of how subsistence farmers around the world are ruining their topsoil using slash-and-burn, it occurs to me that if they’d use hoes to scoop long, very shallow depressions with minimal sloping, stack their detritus in them instead of into piles on level ground, and then burn — they could easily shovel the dirt back into the depression and onto the now smoldering wood. Or, avoiding high temperature charring, simply build not so big piles on open ground and begin tossing dirt onto the smoldering char at the appropriate rate and time. I can visualize how I’d do it; but, it’s hard to describe. After a few years of doing it and laying the successive trenches side by side, as the years went by and tilling proceeded over the years, experience would teach one what more was needed to refine the technique. For example, I don’t know how long it is before crop yields would be boosted after introducing char to the soil, though I believe that once the char is imbued with the nutrients that it has kept from being washed away that the yields will remain higher in perpetuity. I would hope that there are individuals and organizations already engaged in developing the production and use of biochar in areas like the Amazon — I just haven’t read about any.

Note: Though the Amazonians who made Terra Preta famous were wiped out by diseases that the Spaniards with Orellano spread and, thus, their techniques were lost, I’m guessing that some of the NGOs in the Amazon today could work with the indigenous people to revive the methodology / especially in this new age of finding  carbon drawdowns. This includes ‘regenerative farming’ and the use of biochar.