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)

No Miracles

Charcoal cannot replace the need for adding mineral nutrients.

I am an unabashed charcoal enthusiast. Used properly, adding charcoal to soil improves biomass production and soil health. Sometimes dramatically when soil productivity is low. Certainly part of the effect is increased nitrogen use efficiency: less N lost to nitrification and leaching. Charcoal also tends to be associated with higher post harvest soil levels of P and K for reasons that are not entirely clear. Perhaps this effect also is due to increased efficiency.

Most TP enthusiasts, myself included, are convinced that the most mysterious effects from adding charcoal relate to soil biology, more than they relate to direct physical and chemical effects, although those realms play important roles also. And, in keeping with my previous post, it seems clear to me that increased energy efficiency is a critical bit here. Plants and microbes are growing more biomass with less effort for reasons that can't be entirely explained by traditional nutrient-based perspectives. Yes, the charcoal adds potassium, yes it raises soil pH, yes it increases soil water and nutrient holding capacity. But the results speak to more, much more.

The behavior of charcoal amended soil seems to defy the limits of the soil-biology system understood by traditional science. However, it would be entirely foolish to think that simple soil nutritional requirements are not still in play. Nutrient deficiencies limit living systems. Charcoal may promote efficiencies that help stretch the budget in regards to those limits, but in the end, the most limiting nutrient before adding charcoal is probably still going to be the most limiting nutrient after adding charcoal.

What got me thinking about this was consulting soil scientist Doug Edmeades’ posts on soil organic matter. The first, Carbon farming: take-off or rip-off, explored how carbon sequestration efforts can cut both ways. The second, Soil Organic Matter Matters, hits on the most-limiting-nutrient.

Pasture plants need 16 nutrients. Without all 16 the clover will disappear, the pasture will be N deficient, the quality grasses will fail, pasture production would collapse followed by a need to cut back the stocking rate and, given sufficient years, a farm would be back to native pastures and bush. In the process soil carbon levels would decline.

Collapsed pasture production is no idle threat. We know that the collapse of legumes in pasture systems in Europe and in the eastern US helped motivate the expansion of the western US. Against that historical backdrop, Benjamin Franklin famously demonstrated sulfur deficiency when he added gypsum to alfalfa to form the words "This has been plastered". Doug Edmeades mentions this because soil carbon sequestration enthusiasts seem to have temporarily lost track of these limits. The same caution applies to charcoal.

There is great potential for increasing productivity through judicious use of charcoal. However, TP enthusiasts must not lose sight of the fact that charcoal cannot replace the need for adding mineral nutrients.

New Gardening with Biochar FAQ

Note: Bio-char, agrichar, and charcoal are interchangeable terms when it comes to the intentional use of charcoal in the garden.

The argument for encouraging biochar use as a ubiquitous household practice is compelling: Improved garden soil will increase food production where it has the most impact on energy demand. Implementing charcoal manufacture at a household level draws in a supply of yard prunings and workbench scraps that otherwise would be lost to non-charcoal alternatives.

Unfortunately, finding even the most basic information on how to implement biochar use as a personal sustainability practice is discouragingly time consuming. In response I have started up a FAQ, a collaborative wiki, building on the efforts of the TP enthusiast community (1, 2, 3). Maybe you, the concerned gardening public, can help us thresh out the most important questions that need asking. Leave a comment here or at the FAQ. Here's my favorite bit from what has been posted so far:

2.05 What are some less smokey approaches to making charcoal for the gardener?

Choose your feedstock wisely. No matter what technique you use to make charcoal, choosing uniformly sized, dry woody material produces the highest yields. Uniformity is one reason that colliers will routinely use coppiced hardwoods.

Inverted Downdraft Gassification. For a cleaner burning configuration, consider a Top Lit Updraft (TLUD) technique, also referred to as an inverted downdraft gassification. The technique looks simple but in reality it involves some fairly sophisticated principles (PDF). That doesn't prevent success using common materials and dead simple design. Take that same open barrel configuration, tweak the design per the aforementioned sophisticated principles, and now light it from the top instead of the bottom. This takes a different skill set than lighting from the bottom but its also not that difficult to master. A little vaseline or ethanol on a cotton ball can work wonders for starting up. Once the fire gets going, the top layer of wood burns, creating charcoal, naturally. The heat from the top layer burning warms the wood below it releasing combustible and noncombustible gases which flow up into the charcoal layer. Glowingly hot charcoal has a wondrous ability to strip oxygen molecules from of anything that passes over it, so it converts the water into hydrogen, and the carbon dioxide into carbon monoxide. These two gases are flammable. They join with the other flammable gases released from the fuel. These ignite as they mix with air coming into the top of the open barrel above the charcoal layer. The result is a scrubbed gas-fed flame that is much more controlled, and which burns substantially cleaner and hotter than can be achieved with the bottom lit burn barrel. (Source). Insufficient oxygen below the combustion zone impedes loss of the charcoal despite the high temperature flame immediately above it. This allows charcoal to build up faster than it is consumed, at least until the pyrolysis zone reaches the bottom of the fuel column. The downside is that, while wondrously clean burning, a TLUD is challenged to achieve yields above 20% charcoal-to-fuel.

Folke Günther's simple TLUD-fired Retort. A retort works by restricting the air supply to the target feed stock for the duration of the burn. An outside heat source pyrolyzes the retort contents, small openings in the retort allow wood gas to escape, but restrict the flow of oxygen in. While retorts are capable of very high yield efficiency, the open flame used to fire the retort is not as clean as can be achieved with a gasifier. In small retorts, a further inefficiency is that wood gas generated from the retort can end up blowing by the combustion zone without being burned. Folke Günther's elegant solution is to combine a TLUD with a retort. This is easily the cleanest burning and highest yielding method we know of to make garden-sized batches of charcoal.

(Source)

The Charcoal Vision

I want to shout this from the rooftops.

A Win–Win–Win Scenario for Simultaneously Producing Bioenergy, Permanently Sequestering Carbon, while Improving Soil and Water Quality by David A. Laird, USDA-ARS, National Soil Tilth Laboratory

Processing biomass through a distributed network of fast pyrolyzers may be a sustainable platform for producing energy from biomass. Fast pyrolyzers thermally transform biomass into bio-oil, syngas, and charcoal. The syngas could provide the energy needs of the pyrolyzer. Bio-oil is an energy raw material (~17 MJ kg–1) that can be burned to generate heat or shipped to a refinery for processing into transportation fuels. Charcoal could also be used to generate energy; however, application of the charcoal co-product to soils may be key to sustainability. Application of charcoal to soils is hypothesized to increase bioavailable water, build soil organic matter, enhance nutrient cycling, lower bulk density, act as a liming agent, and reduce leaching of pesticides and nutrients to surface and ground water. The half-life of C in soil charcoal is in excess of 1000 yr. Hence, soil-applied charcoal will make both a lasting contribution to soil quality and C in the charcoal will be removed from the atmosphere and sequestered for millennia. Assuming the United States can annually produce 1.1 x 109 Mg of biomass from harvestable forest and crop lands, national implementation of The Charcoal Vision would generate enough bio-oil to displace 1.91 billion barrels of fossil fuel oil per year or about 25% of the current U.S. annual oil consumption. The combined C credit for fossil fuel displacement and permanent sequestration, 363 Tg per year, is 10% of the average annual U.S. emissions of CO2–C.

Soil organisms help ranchers

Intense, low duration grazing builds soil vitality, and increases soil organic matter.

Formulaically, the process described by Manske is very simple; what happens as a result is not.

A rancher chooses three pastures on which to graze the cattle. Starting in the first pasture, the cattle graze for 15 days, and then move on to the next pasture. This is repeated and the cattle find themselves in the third pasture.

Once the cattle leave the first pasture, the soil organisms go to work, converting the organic nitrogen into mineral nitrogen and feeding the plants, building their crude protein.

“Just by changing the management from focusing on dry matter poundage to managing those soil organisms, you can increase the productivity of your land,” Manske said. (Source)

Well observed.

Rhizosperic soil can get awfully puny under long duration grazing. Topsoil pales and topsoil depth is lost, but not to sediment discharge or wind erosion. The in-situ transformation of topsoil to not-topsoil results in the discharge of soil carbon to the atmosphere. The good news is that, unlike wind erosion, water erosion, sheet erosion, or gully erosion erosion, this yet-to-be-named variant of topsoil erosion is reversible.

Washington State Biochar Research

Washington State University researchers will produce biochar (a residue potentially used as a soil amendment) from low temperature pyrolysis of biomass materials. The biochar will be tested for its potential to store carbon, evaluated for any growth effects on plants in the greenhouse, and assessed for economic impacts. Research on biochar has shown promise in long-lasting carbon storage and improved crop production. This research will be the first rigorous study of biochar use in agricultural soils in this state. (Source)

Agrichar trials in NSW

News and commentary on agrichar is flowing steadily this spring, first with the reporting on the 1st annual Agrichar Conference, and now with the reporting on initial agrichar trials by the New South Wales Department of Primary Industries (NSW DPI). Particularly encouraging is that the sophistication of the comments continues on the increase.

Snippets from ABC' Discovery channel ...

Recent greenhouse trials found soils mixed with the charred waste, called agrichar or biochar, were more attractive to worms and helpful microbes.

Agrichars trialled by NSW DPI include those from poultry litter, cattle feedlot waste as well as municipal green waste and paper mill sludge. Each agrichar has its own characteristics and interacts differently with different soil types.

Some agrichars raise soil pH at about one-third the rate of lime, raise calcium and reduce aluminium toxicity.

Kimber said more research needs to be done on working out which agrichars are best for which soils and on the impact of any contamination in biomass.

... reinforce the need for local pyrolysis pilot projects. The pyrolysis pilot hurdle is necessary where widespread agrichar use is the goal. Clean air concerns combines with the limited supply of local expertise and experience needed to achieve the low-temperature pyrolysis ideal for producing agrichar.

I have submitted comments emphasizing the need for pilot agrichar projects to our State's climate change folks.

(AP image source)

Biofuel demand pencils out to damaged soil

Crop residue is not a waste. It is a precious commodity and essential to preserving soil quality.

Production systems must be developed so that ethanol produced must be at least C neutral if not C negative. Temptations [to mine soil vitality] aside, biofuels produced from crop residues may neither be free nor cheap.

Rattan Lal, SSSA President, has a timely message to his fellow Society members in the May issue of CSA News (regretfully subscription only). It is that we must take this opportunity to break the cycle of soil destruction that characterizes the rise and fall of civilized man. Biofuels adds unprecedented value to biomass production. Rattan Lal sketches out the numbers, comparing potential demand to crop residue available. With demand tracking above supply, the temptation is to mine the soil of its vitality. Rattan Lal observes that soil exploitation is the primary contributing factor to desertification.

Harvesting crop residues for use as fodder for livestock, residential fuel for cooking and heating, construction material, and other competing uses is a reality in sub-Saharan Africa, South Asia, China, and other developing countries. Therefore, it is not surprising that these are also the regions that have been plagued with severe problems of soil degradation.

With a severe decline in physical quality, degraded soils do not respond to fertilizers even if made available at a subsidized price. Adverse effects of none or low rates of applications of fertilizers and other amendments on agronomic production and soil quality have been exacerbated by the perpetual and indiscriminate removal of crop residues coupled with uncontrolled and excessive communal grazing.

The stubborn trends of low crop yields and perpetual hunger and malnutrition in sub-Saharan Africa and in regions of rainfed agriculture in South Asia cannot be reversed without returning crop residues to the soil and also supplementing them with liberal applications of other biosolids.

Rattan Lal has done an admirable job in this appeal to the his fellow SSSA members. He has included constructive comment on tools and processes available to make biofuels production compatible with maintaining soil vitality. But the undercurrent message is that those of us who love soil must involve ourselves in the process, the policy, and the public discussion of our transition to sustainable energy.

Leave comment or email me if you would like to request a copy of Rattan Lal's May address. Or better yet, join SSSA.

Agri Char Conference Reviews

Agri-char aka bio-char is the key ingredient in soil scientists' holy grail, terra preta nova (my previous mention). Initial reports from participants at the first meeting of the International Agrichar Initiative indicate continued hope that agrichar amended soils could contribute significantly to our planet's health and productivity.

Kelpie Wilson, Truthout's environment editor, writes:

Charcoal's pores also make excellent habitat for a variety of soil microorganisms and fungi. Think of a coral reef that provides structure and habitat for a bewildering variety of marine species. Charcoal is like a reef on a micro-scale.

Over at the Sydney Peak Oil forum, attendee burko writes:

It would be very easy to become enthusiastic about the future of these integrated technologies. However, there is one overriding impression of this field to keep in mind – it is brand, spanking new. So new that even the choice of name Agrichar is being debated. There are no books; there are few years of experience even amongst the researchers; the debates about the benefits to AGW are only just beginning.

In short, being a part of the conference could be compared to hearing an orchestra tuning up. There are skillful cellists and masterful tuba players preparing next to each other. The idea is potential for beautiful music, rather than cacophony. We aren't really sure who the conductor is yet – plenty of skillful people are taking part of that role. There is cooperation and the desire to share experience at all points – but this is a new kind of orchestra.

While the soil biology alone is a staggering subject, we should be as interested in the methods of producing the black carbon. Burko writes on pyrolysis:

The gas produced is referred to as syn gas, called producer gas sometimes.

My formative understanding of the process says something like this – if you want to produce non-activated chars, temperatures need to be constrained below the levels that gasification requires in order to make the reaction sufficiently exothermic to be self sustaining.

Of course, there is more to it than that – I did find that combustion engineers found it difficult to provide a simpler explanation.

I did get one useful figure from Dr Robert Brown, from Iowa State University – if you're burning wood in an open fire, you're probably only getting a third of the heat energy that should be possible from gasification – a pretty compelling reason to try and understand this stuff. It's been said that up to a third of the worlds deforestation happens in the name of inefficient cooking fires.

From the reports, it is clear that the number of players, and their diversity, is growing exponentially. One reason for this diversity is that the process of making terra preta nova appears to be as adaptable to a wide range of soils and climates as it is scalable. You can have regional collection and distribution approaches coexisting with processes adapted to individual enterprises. The plan at Fourth Corner Nurseries (mentioned previously) near Bellingham, WA is a great example of both points. The operation already amends the soil with char. Observed better root growth confirms what we already sense, that black carbon can have a positive effect on a wide range of soils. The nursery plan to use surplus biomass from their willow coppice field to power the nursery and to produce char is easier said than done, but is brimming with promise.

Image: Scanning electron micrograph of a conductive carbon sticky tab. (Flickr - St Stev)

Rejuvenating Soil Life Requires Patience

Soil data is "noisy" data. Being a difficult medium to observe and measure, soil has an almost weird capacity to mask change.

In several instances that I can recall, it seemed improvement in soil carbon status was not evident until several years after a change in management was made. The increases in soil organic matter called intervening data into question.

You can see similar data fluctuations due to individual samplers, but this delayed stepping pattern of carbon increase happens a little too often to ignore. It is as if the momentum for an increase in carbon must first collect in the biological dynamic of the soil, invisible to our simple agricultural analysis tools where we measure TKN, TOC and C:N ratios. Those were my thoughts as I read the following:

The Four Phases of No-Till

Phase one, initialization, occurs in the first five years. It is where soil structure starts to improve and microbial activity increases. Additional nitrogen is required to do that.

"As organic matter increases, you need the added nitrogen to make more of it," Towery said.

The second phase is transition from the fifth to tenth years. This is when organic matter accumulates, soil aggregation and soil microbial activity elevates, phosphorous accumulates, and nitrogen immobilization and greater mineralization occurs.

Phase three is consolidation, from 11 to 20 years. In this period, carbon accumulates and additional water is available in the soil. Further nitrogen mineralization and immobilization occurs and there is an increase in cation exchange capacity (CEC) and nutrient cycling.

"These years aren't perhaps exact, because this phase depends on your latitude and your soils," Towery said.

The fourth and final phase is maintenance, which comes after 20 years. It brings a continuous flow of nitrogen and carbon, greater availability of water and high nutrient cycling with increases in nitrogen and phosphorus.

"Twenty years is a long time. It's not like you've arrived at the Promised Land but things do change with the soil," Towery said. "It's because it is a dynamic system. The technology and management strategies you use changes over time as you go from phase to phase.

"One change we underestimate is the changes in soil biology. We can't see them but they're there."

Photo: No-Till Milo in Wheat Stubble

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