Saturday, December 13, 2008

Pedology and CO2

In a previous post I provided an oblique link to a news release: Climate Change Alters Ocean Chemistry. It makes reference to conditions resonating with the theory of biorhexistacy:

The research team, which included Caldeira, Elizabeth M. Griffith and Adina Paytan of the University of California, Santa Cruz, plus two other colleagues, studied core samples of deep oceanic sediment recovered from the Pacific Ocean Basin. By analyzing the calcium isotopes in grains of the mineral barite in different layers, they determined that between 13 and 8 million years ago the ocean’s calcium levels shifted dramatically. The shift corresponds to the growth of the Antarctic ice sheets during the same time interval. Because of the huge volume of water that became locked up in the ice cap, sea level also dropped.

“The climate got colder, ice sheets expanded, sea level dropped, and the intensity, type, and extent of weathering on land changed,” explains Griffith.

“This caused changes in ocean circulation and in the amount and composition of what rivers delivered to the ocean,” adds Paytan. “This in turn impacted the biology and chemistry of the ocean.”


These folks are saying that momentous changes in oceanic chemistry recorded in the sediment record must have been predicated by equally momentous changes in soil chemistry, changes tied to both atmospheric carbon dioxide content and climatic conditions.

From a pedologist's view, it is clear that under the expanded humid, warm, stable conditions envisioned by H. Erhart for biostasis, we would see deeper residual soils and more rapid formation of argillic horizons. In terms of soil taxonomic orders (USDA), more intense chemical weathering would cause the expansion of inceptisols at the expense of mollisols, ultisols at the expense of alfisols, and oxisols at the expense of ultisols.

Caldeira and company tie warm climate to higher river calcium content, but strongly implicate higher atmospheric carbon dioxide as the primary driver of increased chemical weathering. Atmospheric carbon dioxide levels do not appear to be part of Erhart's construct, but could certainly enhance these pedogenetic trends.

Acid rain alarm bells are ringing faintly in the distance at this point. But it is a false alarm. Rain water pH is due mostly to equilibrium with atmospheric carbon dioxide. The carbonic acid formed buffers rain drop pH to 5.6, and higher atmospheric carbon dioxide increases the carbonic acid content, but it doesn't lower pH below 5.6. Other constituents accomplish that. Thus increased atmospheric carbon dioxide isn't being implicated in some futuristic acid rain scenario.

Oxisols, ultisols and spodosols would increase in extent with increased soil weathering. But could it also mean lower plant disease, and more nutritious crops? Increased carbonic acid would drive faster pedogenesis, as would increased the biological activity stimulated by higher carbon dioxide. For soil, that would mean a richer solute content in the soil water, more rapid formation of secondary minerals, more eluviation or translocation of minerals with percolation. To the list of pedological shifts at the soil order level, we can add the expansion of spodosols at the expense of inceptisols.

Something very positive can be expected for soil that is not captured in the shifting soil order paradigm. For plants and soil microbes, richer solute content would mean greater availability of mineral nutrients. In soil husbandry and slow food circles, higher mineral availability translates to healthier soil, lower plant disease, and more nutritious harvests. What the shifting soil order paradigm does signal is that soils will be at greater risk of losing their fertility to leaching. Having the soil chockablock full of biochar will be essential to mitigate this last effect. Let's start now.

(Recycled from nscss.org)

8 comments:

Erich J. Knight said...

A climate change mitigation technology;

FOR IMMEDIATE RELEASE: December 12, 2008

POZNAN, Poland, December 12, 2008 - The International Biochar Initiative (IBI) announces that Micronesia has filed a submission at the UN Framework Convention on Climate Change (UNFCCC) proceedings underway in Poznan to introduce biochar as a technology for consideration as a "fast-start" strategy to "mitigate climate change in the immediate near-term." The submission places biochar on the draft agenda to be considered during UNFCCC negotiations in Copenhagen in 2009.

Micronesia's proposal follows the filing of a submission by the United Nations Convention to Combat Desertification (UNCCD) endorsing biochar earlier this week. The UNCCD, a sister convention to the UNFCCC, identified biochar as a unique opportunity to address soils as a carbon sink, in line with its 10 year strategic program that calls for the promotion of low-carbon footprint sustainable practices and technologies that assist affected countries in the implementation of their National Actions Programs to Combat Desertification and Drought.

IBI Executive Director Debbie Reed said, "This is an incredibly important achievement, since Micronesia, as a UNFCCC country party, has officially positioned biochar as a mitigation technology for adoption even prior to the post-2012 framework. The UNCCD submission was an excellent start to what we sought here in Poznan, but the Micronesia submission offers a chance to jump-start efforts to adopt biochar as a climate change mitigation technology."

Biochar is a fine-grained, highly porous charcoal that helps soils retain nutrients and water, resulting in increased soil fertility for agriculture. The carbon in biochar resists degradation and can sequester carbon in soils for hundreds to thousands of years, providing a potentially powerful tool for mitigating anthropogenic climate change.

For Micronesia, an island state, early and rapid actionon climate change is of utmost importance. Micronesia has identified biochar as one of a few "action commencing now" technologies that make up an essential "fast start strategy." Micronesia's submission states: "A focus on fast-action strategies offers great advantages particularly to LDCs, small island states and other states vulnerable to extreme weather events and flooding."

Micronesia endorses "Promoting biochar carbon sequestration as a near-term carbon mitigation and storage strategy, which removes carbon from the carbon cycle by drawing down atmospheric concentrations of CO2 in a carbon-negative process and provides near permanent carbon storage while also improving soil productivity and reducing the need for fossil fuel-based fertilizer."

Micronesia also emphasizes the "strong co-benefits" of proposed near-term strategies, including "soil enhancement from biochar."

Underscoring both the co-benefits and the early and rapid action potential of biochar, the Secretariat of the United Nations Convention to Combat Desertification (UNCCD) hosted a side event on Thursday titled: "New stoves for rural households to capture carbon, reduce deforestation, and improve soil fertility." The event introduced the concept of mobilizing rural households to adopt new high-efficiency cookstoves that reduce emissions and also produce charcoal that can be incorporated into soils for both carbon sequestration and soil improvement.

The side event was chaired by Gregoire de Kalbermatten, UNCCD Deputy Executive Secretary, and speakers included: Sergio Zelaya, UNCCD; Barney Dickson, Head of Climate Change and Biodiversity, UN Environmental Program, World Conservation Monitoring Center; Debbie Reed, Executive Director of IBI; and Robert Flanagan, President of S.A.F.F.E (Sustainable Agricultural Food and Fuel Enterprises) Ltd.

Speaker Barney Dickson emphasized the considerable potential of dryland soils to sequester carbon to combat climate change and enhance soil quality. Dickson said that drylands cover about 40% of the Earth's land surface (excluding Antarctica and Greenland) and that total dryland soil organic carbon reserves comprise 27% of global soil carbon reserves. He said that the fact that many of the dryland soils have been degraded means that they are currently far from saturated with carbon and their potential to sequester carbon may be very high.

Delegates from both developed and developing countries attended the standing room only event. Following the talks, many delegates expressed interest in including biochar in their development strategies and in working with the IBI on IBI's Developing Country Initiative to introduce and evaluate biochar production technologies at the household and village/neighborhood level.

The submission from the Federated States of Micronesia can be accessed here: http://unfccc.int/meetings/ad_hoc_working_groups/lca/items/4578.php

To access the UNCCD's submission on biochar, go to http://biochar-international.org/ibimaterialsforpress.html and open the document titled: "Biochar in the UNFCCC Policy Context"

Additional information on the UNCCD and biochar on http://www.unccd.int/publicinfo/poznanclimatetalks/menu.php

About IBI

The International Biochar Initiative (IBI) is a registered non-profit organization that serves as an international platform for the exchange of information and activities in support of biochar research, development, demonstration and commercialization. IBI participants comprise a consortium of researchers, commercial entities, policy makers, development agents, farmers and gardeners and others committed to supporting sustainable biochar production and utilization systems that remove carbon from the atmosphere and enhance the earth's soils. www.biochar-international.org

For further information, please contact:

Debbie Reed, Executive Director and Policy Director, International Biochar Initiative
Phone: 202-701-4298 email: Debbie@biochar-international.org

Thayer Tomlinson, Communications Director, International Biochar Initiative
Phone: 914-693-0496 email: info@biochar-international.org

Marcos Montoiro-Allue, Communication Officer, UNCCD
Phone: 0049-228-815-2806 email: press@unccd.int

John Freeland said...

Hi Phil:

This is an interesting post. Regarding the following:

"Caldeira and company tie warm climate to higher river calcium content, but strongly implicate higher atmospheric carbon dioxide as the primary driver of increased chemical weathering."

Given that the CO2 content in soils is there primarily due to microbial respiration and decomposition, and the CO2 concentration in soil pores is already something like 20 times higher than the atmospheric concentration, would rises in atmospheric CO2 directly have a significant impact on soil chemistry?

Philip Small said...

Hello John:
Increases atmospheric CO2 will increasingly buffer precipitation at an acidic pH which directly supports higher soil weathering. This is an input into the soil system that respiration cannot be expected to mask.

There are also biological consequences of increased atmospheric CO2 that translate to accelerated pedogenesis. AKA carbon dioxide fertilization, the effect is expected to expand rhizospheric soil volume laterally (shrinking desertification) as well as vertically, with soil (and pedogenesis) reaching further and more intensely from the soil/atmosphere interface.

John Freeland said...

From your post:

"Acid rain alarm bells are ringing faintly in the distance at this point. But it is a false alarm. Rain water pH is due mostly to equilibrium with atmospheric carbon dioxide. The carbonic acid formed buffers rain drop pH to 5.6, and higher atmospheric carbon dioxide increases the carbonic acid content, but it doesn't lower pH below 5.6. Other constituents accomplish that. Thus increased atmospheric carbon dioxide isn't being implicated in some futuristic acid rain scenario."

Doesn't that contradict your point: "Increases atmospheric CO2 will increasingly buffer precipitation at an acidic pH which directly supports higher soil weathering..." ??

I do believe the fertilizer effects of higher atmospheric CO2 would (or could) expand the rhizosphere,which would likely accelerate weathering.

Philip Small said...

Acid rain is capable of denuding landscapes.

Rainwater at pH 5.6 is not capable of denuding landscapes.

Hello John:

Rain at pH 5.6 does not meet the definition of acid rain because that is the normal background pH of unpolluted rain. Increasing atmospheric carbon dioxide will not lower the pH of rainwater such that it will meet the definition of acid rain.

However we can expect increased atmospheric carbon dioxide to increase the carbonic acid content of the rainwater, the molarity if you will. This higher concentration of acid doesn't change the pH, but it does result in taking less rain fall to acidify a soil, when that soil starts out with a pH above 5.6, a fairly normal soil condition.

Philip Small said...

More...
See Wikipedia: Carbonic Acid where it relates partial pressure of CO2, pH of (rain) water, and concentration of carbonic acid in mol/L.

Compare current condition (pCO2(atm)=3.5x10-4) to one with 285% higher atmospheric CO2 (pCO2(atm)=1.0 x10-3). pH decreases to 5.42 (acid rain, yes, but at an "early warning" level, relatively benign) and concentration increases 285% from 2.0 x10−8 to 5.7 x10-8 mol/L.

That's still not enough acidity to devastate the land, but it is certainly enough to affect pedogenesis.

I don't mean to trivialize the not-related-to-soil effects of increased atmospheric CO2: O2 partial pressure controls the calcification rate of coral communities, and greenhouse effects on temperature are more than just an interesting theory.

John Freeland said...

Hi Philip:

I think we are finally in agreement. This is an interesting issue - linkage between atmospheric and soil (and oceanic) carbon. A related one, mineral carbonation, is, as you know, a hot topic with respect to carbon capture and storage (CCS).

For geologic CCS, pumping CO2 into the ground amounts to introducing a weathering agent to a mineralogic environment that may be susceptible to weathering, producing new weathering products.

As soil scientists, we need to bring these issues forward.

Philip Small said...

John: Appreciate you holding my feet to the fire.