Wednesday, September 26, 2007

Biochar Packing Strategies

In my last post, we arrived at the conclusion that the one key crop that can make biochar production feasible for agriculture is corn. It is also apparent that a naturally built stack without much work will produce some biochar, certainly enough for the owner to recognize the value of the product and to want to improve his efficiency.

The first need is to develop an earthen kiln strategy that can hugely increase production. shoveling dirt is an option, but likely very unsatisfactory, difficult to control during the burn, and very labor intensive. Digging a pit can perhaps help improve this situation and may have been a viable option. however, the average pit needs to contain ten tons of material and a typical five acre field will need several pits. This requires an incredible amount of additional labor to execute properly. So although suitable for pottery making, It is a much less practical approach with field operations. And we still have to pay attention to packing.

This is were my understanding of the nature of the corn root ball led me to the conclusion that much more sophisticated packing strategies were available to the farmer that hugely lowered the labor needed to move dirt. The corn root ball consists of a poorly rooted flat disc sitting on the top of the soil. Penetration is less than three inches, while the disc itself is several inches across. It is easily lifted in most soils by the simple expedient of grabbing the stalk and pulling.

We suddenly have a packable source of biochar with its own contribution to the earthen wall attached. What was the farmer waiting for? The remaining question is how best to pack the stalks and to simultaneously build the outer wall of the earthen kiln. So far I have imagined several packing strategies that could work, although they all have to be tested.

But I think that we can all agree that a stalk of biomass with a brick attached is a great start. As good as a box of Leggo.

I see two strategies. One in which a windrow is build with one side forming an earthen wall. Remember that in order to achieve tight packing it will be necessary to overlap the root balls at least three deep creating a mud wall several inches thick. They may also have packed other material among the stalks to improve packing. I think that Cassava is particularly suitable.

A second windrow can then be build against the first windrow on the non walled side. This then still leaves you with the task of covering the exposed stalks with dirt but primarily unto a flat surface. Any type of variation of this packing approach should work very well.

The second strategy is to lay out a 12X12 square and lay in packed layers at right angels to each other with the earthen wall on the outside. We end up with a well packed interior and an outside earthen wall perhaps several feet high completely surrounding the material.. A thin layer of dirt on the top of this stack will then close the kiln.

This is obviously the most attractive approach provided the packing ratio can be maintained.

In all cases, the burn is initiated by carrying an earthenware platter (unfired) full of glowing coals unto the top of the heap, dumping them unto the stalks and then tipping the platter on top of the coals as a shield, and then covering it all with dirt. A crew then watches the heap for breakouts, in order to throw extra dirt as needed.

Observe that we have minimized the labor input throughout. A lot of extra time will be spent of getting the packing right, but that is not onerous. Building a layer of dirt onto the top of the 12X12 heap will move perhaps a ton of dirt which will mix nicely with the ton or two of produced biochar. This is not unreasonable. The produced biochar and dirt mixture can be then carried in baskets back to field to renew the seed hills in time for the next crop.

The point that I would like to make here is that this protocol allowed the ancient farmer to have his terra preta soil immediately and made corn culture possible in tropical soils as proven by pollen analysis. There was no multi season delay in establishing terra preta.

And rather obviously, the same approach today can revolutionize indigenous agriculture globally. And rather obviously also, there is no particular need to do most field once it has been done at least once. The carbon continues to hold nutrients for a very long time.

From the perspective of sequestering carbon, we want this done twenty to fifty times. From the perspective of building a viable soil base, several times should be more than ample.

You realize folks, that this is a total and unexpected revolution in agriculture that can increase agricultural production globally by even an order of magnitude.

All depleted soils can be put back on line everywhere, and the unusable tropical soils can achieve year round high volume production.

And we were only trying to sequester CO2

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