Are Bio-Oils in Char Important?

Posted on July 24th, 2008 in Theory by ajmorris

Many sites on the Internet claim that biochar should be made from wood charcoal, made from low temperature pyrolysis:

Low temperature woody charcoal (not grass or high cellulose) has an
interior layer of bio-oil condensates that microbes consume and is
equal to glucose in its effect on microbial growth (Christoph Steiner,
EACU 2004). High temp char loses this layer and does not promote soil
fertility very well.

From: http://www.eprida.com/hydro/yahoo2004.htm

That concept reduces biochar to a fertilizer, and if it were true, means that the charcoal component of Terra Preta soils is not the reason for the persistent high-fertility of those lands, since the bio-oils would certainly have been entirely consumed thousands of years ago.

Also, many researchers are finding biochar derived from non-woody sources such as rice hulls, corn husks, etc., are also highly beneficial, so it can not be bio-oils if those are only produced by woody materials, as stated. Either non-woody material also produces bio-oils, or it is not that important.

Only long-term testing will tell if the beneficial effects seen so far are due in part to bio-oils (in which case the long-term fertility seen in Terra Preta remains a mystery), or if it is the charcoal itself providing the observed improvements, through fostering biotic communities and cation exchange properties. Given the initial research results, I’m betting on the charcoal.

Does Biochar Raise Alkalinity of Soil?

Posted on July 21st, 2008 in Theory by ajmorris

One of the most absurd statements I often hear repeated about biochar is that it raises the alkalinity of soil it is applied to. Media loves to jump to such simplistic conclusions based on one particular study or another — but ask yourself — does that make sense?

I am first to admit that I am not a soil scientist, my degree was in the ’soft’ sciences of Anthropology and Psychology and I worked as an archaeologist — a field that struggles to be scientific but is hampered by the nature of its subject matter. It is very difficult to design meaningful scientific experiments about the past. But even my rudimentary scientific understanding suggests that adding any substance to soil will have an acidifying, neutral or alkaline effect, depending not just on the substance, and its pH, but on the pH of the soil it is added to. Adding a neutral (pH 0) material to acidic soil will tend to make it more alkaline, since the total volume of soil has been increased with no increase of acidic chemicals.

So if biochar were neutral, or slightly alkaline — it would decrease the alkalinity of soil that was highly alkaline to begin with — by diluting that alkalinity. The same biochar added to highly acidic soil would indeed, make it more alkaline. Both those scenarios assuming biochar that is neutral or slightly alkaline.

In fact, the pH of biochar depends on several factors, primarily the source material from which it is made, and the temperature at which it is formed. I have not found any controlled studies of this, but reports from an amateur researcher showed that pine needles used for biochar are likely to reduce alkalinity of soils that are alkaline to begin with.

Making a blanket statement that biochar increases alkalinity defies logic. I think that in most cases, biochar, if it is highly carbonized so that minimal organic oils remain, will move a soil toward neutrality — be that lower acidity or lower alkalinity, depends on the initial pH of the soil.

Remember too that biohchar is not a fertilizer. If the soil is highly alkaline to begin with, it will probably need a good dose of compost to increase fertility — which will also usually lower alkalinity — and adding biochar will just make that composted soil more efficient and more effective.

Certainly, more experimentation is needed. Try it out on your own soil, with and without added compost. If it works — use it! If not, let us know why.

The Global View

Posted on July 8th, 2008 in Theory by ajmorris

Environmentalists who seek a solution to the excessive production of Co2 — that is one of the leading causes of global warming — tend to seek solutions in two arenas: reduced energy consumption and alternate energy sources that do not produce carbon dioxide. A recent NewYorker article looked at just such a scenario, with an ‘It can be done’ attitude, in The Island in the Wind.

That article describes a conservative Danish farming community, and tells how they went from the typical energy usage model to becoming an energy-producing entity, in just ten years. Given the particular location, wind energy was the solution to much of the production-side of the equation, and various smaller scale technologies contribute to the consumption side of the balance.

The second half of the article looks at a Swiss program to promote a 2,000 Watt lifestyle (i.e. 2000 watts of energy, or 2 Kilowatts/hr, or 48 Kw per day — 17,520 Kw per year). If this were just electric usage it would be relatively easy, but this is total energy consumption — electric, gas, natural gas, oil, etc., including the energy needed to produce the consumer items people buy. The average American uses six times this much energy.

While the Danish example is encouraging, and the Swiss analysis is enlightening, the real world will not adapt these technologies fast enough to slow, let alone stop, global warming. These are laudable goals that should be pursued, but it is unreasonable (or idealistic) to expect them to take hold within the time frame needed to stop the devastating effects of our warming Earth and acidifying oceans. We need something that will work faster and be so economically attractive that it will be easy to convince people to adopt it.

That something, of course, is biochar. With biochar, it is simply a matter of education, then self-interest will ensure it’s adoption on a massive scale. Infertile soils will show the most immediate benefit from biochar, so those communities with marginal agricultural capacity should be targeted first. Among richer environments the benefit is more long-term — less fertilizer and irrigation is required — but they will come along when they see those marginal soils suddenly competing with them on equal footing. Finally, currently non-productive soils can be turned to agriculture or forestry by biochar amendment, (with some fertilization and irrigation) once the method has been fully proven.

Large scale usage of biochar will offset current fossil-fuel abuse for a while, giving us time to bring that under control. With bichar, about 30% of the biomass is consumed (burned) to carbonize the other 60% — but biomass, by its nature, tends to release its carbon back into the atmosphere — if not by burning, then by rotting. So the 30% that goes into the atmosphere probably would have done so anyway, along with the 60% more that is now available for sequestration.

With fossil fuels — oil and coal — that is carbon the Earth has naturally sequestered already — if we don’t dig it (or pump it) up and use it, it remains sequestered. Adding biochar to the soil will sequester most of that carbon (not all, under some circumstances bacteria can break-down even charcoal). Luckily for us, the byproducts of this sequestration are increased plant productivity, reduced run-off pollution and producing soil that is better in texture and pH.

So we need to pursue the technological means of carbon use reduction, but that alone will clearly be too little too late. In concert with reduced consumption, we need to introduce carbon-negative biochar production and usage, to offset inevitable Co2 production, while so enriching soils that they not only sequester Co2 long-term through biochar, but increased productivity — providing short-term sequestration through increased biomass production.