Wednesday, February 20, 2008

Bacteria as Carbon King

Picking up on a comment made earlier this week that the carbon content of bacteria et al is similar in magnitude to the plant content. More simply put, woodland holding thirty tons of plant carbon will have an additional thirty tons of bacteria content. In one way this explains a lot.

The collapse of soils after the advent of the plow was never quite explained by the erosion model. And the argument that soil growth itself was imperceptible taking centuries to achieve seemed a little extreme.

It is much more satisfactory to have soil act as an agency of the plant life that quickly moves to fill an available niche that once filled stabilizes. Bacteria would be large part of such a process.

It still takes decades to fully establish a new soil in this protocol and it is still very hard to discern. What is different is that we are no longer calling on only the medium of plant destruction to form our soils. Aeration caused by the plant root systems and the accumulation of the remains of single celled organisms contribute as much.

I think that we all sort of knew this but had to be reminded of the actual magnitudes involved.

This begs yet another subject. Single celled organisms able to utilize methane and sulphides are found deep within the rocks of the earth. Even rocks formed by the cooling of molten magma develop extensive fracturing quite capable of holding bacteria. Sandstones have porosities approaching even thirty percent. In any event most have no problem holding oil and gas.

This represents a bacteria holding capacity that hugely exceeds the thin coating of soil on top of miles of rock. I do not think anyone has ever tried to put a number on any of this. I only note that the actual biological carbon in existence may in fact be hugely under estimated.

The deep stuff may have little impact on surface conditions but I don’t think that we should ignore it.

This brings me back to the subject of terra preta. It is clear that the presence of finely divided elemental carbon in the soil contributes in some manner to the creation and maintenance of fertile soils. This is also true for zeolites. This suggests that the interaction between bacteria and elemental carbon in the soil is instrumental in the manufacture of high quality soils and their preservation.

Recall that normal tropical soils are able to maintain only a semblance of fertility in the face of heavy rainfall. With nothing else changing, we have terra preta maintaining top fertility year after year with no help except the return of crop wastes. The question is what is the mechanism that retains nutrients in this soil?

I have been quick to point to the super acid nature of the carbon but had little to add regarding the means. It would make sense for the bacteria to interact with such carbon to retain the nutrients. How this could happen is not known to me.

However, remembering the biosphere as ecology of single celled organisms first is an important initial step to avoid a misleading focus on the more visible plants.

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