Soil pH and Plant Nutrients

Doug Edmeades gives out sound advice on pH.

It used to be believed (going back to the early days of soil science) that the ‘ideal’ soil was neutral: neither acid nor alkaline it had a pH of 7.0. This early belief still prevails especially in Charlatanville. However, with the benefit of much subsequent research our view of the ideal soil pH has changed.

First, it is now known that different plants have different tolerance to acidity. Restricting the discussion to pasture species, browntop is very tolerant to acidity which is one reason why it thrives in undeveloped soils. Ryegrasses are more sensitive and like a higher pH. Clovers are more sensitive again and, of the legumes, lucerne is very fussy. Our pastoral agriculture is focussed on growing clover-ryegrass and the optimal pH is 5.8-6.0 – this is the pH at which pasture production and especially clover production is optimised. In contrast, a straight lucerne stand requires a pH of about 6.5.

Liming pastoral soils above pH 6.0 is not recommended for several reasons. First, there is no benefit in terms of production and it can have detrimental effects on both pasture production and animal health. As the soil pH increases the availability of soil molybdenum (Mo) increases and thus the pasture Mo content increases. This can, in some cases, induce copper deficiency in animals. Also, increasing the soil pH above 6.0 reduces the concentration of soil zinc (Zn) and manganese (Mn) concentrations. This can result in induced Zn and Mn deficiency. Liming soils, contrary to popular belief, is not always beneficial!

He also works up a sensible New Zealander's criticism of liming to "fix" the Ca:Mg:K ratio.

Lime is typically calcium carbonate. For us in New Zealand the active ingredient in lime is the carbonate not the calcium (Ca). Our soils fortunately are rich in Ca – indeed often awash with Ca – a result of their origin (from the sea) and youthfulness (not very weathered).

Given that the benefits of liming are related to the change in soil pH then it should be obvious that the only useful guide and hence measurement for the requirement of lime is the soil pH. This is the adopted science-based approach used in New Zealand.

So what about all this base saturation ratio argument? In the 1930s there were two competing theories about plant nutrition. One said that the ratio of the nutrients Ca, Mg, K and Na was important. These were measured as the proportion of the soil cation exchange capacity (CEC) – the ability of a soil to store these nutrients called cations. Thus your hear some say that the Ca saturation of a soil is 50% meaning that 50% of the CEC was occupied by Ca. The other theory was that plants did not care what the ratio of nutrients were – the plant was fine providing the minimum amount of each nutrient was present. This is called the Sufficiency Theory distinguishing it from the Ratio Theory.

After almost 80 years of research the jury is definitely in. The Ratio Theory is not consistent with observations and hence is now set aside. Indeed we now know that using the Ratio Theory as a basis for fertiliser recommendations can be and often is misleading. For example the Base Saturation Ratios of Ca in most New Zealand soils would suggest they are Ca deficient. The fact is they are not and Ca deficiency has never been recorded in New Zealand.

There are other problems with the Ratio Theory. It applies to only 3 nutrients (Ca, Mg and K – appreciating that Na is not required for plant growth (except on some crops such as sugar beet).

What about all the other 13 plant nutrients? Also we now know that soils have variable charge – this realization has occurred within my 30-year career. The consequence is that the CEC depends on the pH at which it is measured. The old method still used by the quack brigade measures the CEC at surprise, surprise the “ideal” soil pH of 7.0. This inflates the CEC thus reducing the base saturation ratios, especially for Ca. By sticking to this now disproved methodology the quacks can be certain that the soil test results will say the Ca base saturation ratio is low therefore apply my product because it contains Ca.

My region's soils are similarly well supplied with calcium. My agricultural consultancy mentors taught me to be skeptical of the Ca:Mg:K approach to evaluating soil nutrient status. In my region it was used to justify expensive formulations of foliar applied applied calcium, or to justify adding expensive soluble calcium to the irrigation water on soils with a good supply of calcium. Normally on high value crops in good years when adding extra nutrients for insurance has legs. Charlatans is not too strong a word. Back in the 1980's these folks would use A&L Laboratories, well established, amny offices, with an excellent professional reputation, and which reported Ca:Mg:K in a ratios friendly format. I'll bet this is still the case. You can't beat something like that for conferring legitimacy, can you?

The originator of the ratios approach, soil scientist William Albrecht was a brilliant observer of nature with a considerable body of work which still gets a lot of play. The basic premise of Albrecht's 1938 Loss of Soil Organic Matter and Its Restoration is solid: it takes a ready supply of soil calcium and nitrogen to build soil organic matter. His concepts continue to be stretched beyond to the breaking point both by well meaning folks exchanging advice on organic farming methods, as well as in efforts to sell product to the unsuspecting. Yet we don't read much in the way of criticism of the ratios approach. It is excellent of Doug Edmeades to voice his concern.

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.

Dynamic Earth blogs on Soil Science

Eric, over at Dynamic Earth is blogging on about soil science.

Soils are a lot like pornography: you know em when you see em, but everyone has a hard time agreeing on a definition.

True that. Eric's posts are a pretty quick study (its a blog after all) of a complex subject, and he does an admirable job of organizing the popular understanding of soil. I shouldn't expect, but I always look for, even the briefest nod to including energy as fascinatingly important to the understanding of soil, at least as equally fascinating as the physical, chemical, and biological characteristics.

Soil classification is only a beginning in pursuing a deeper understanding of the more dynamic characteristics of the soil resource. Nikiforoff's 1959 definition of soil as the "excited skin of the sub aerial part of the earth's crust". (ref) speaks to that energy. We all recognize that soil involves energy but we have been slow to engage in an understanding of that energy as a component of the dynamic earth.

Most of what has been studied regarding energy in soil is in relation to remediation of contaminants, preventing corrosion, waste treatment, and wetland chemistry: small but practical subsets of the knowledge we need. And we do use energy states and gradients to characterize soil (redox, pE), so it is not like energy is ignored. It is just that the labels we present it under do not communicate energy. Wetland chemistry, bioremediation, phytoremediation, geobiochemistry, soil ecology: these are not terms that alerts one to the fact that energy is the fundamental driver. That our soil projects are nonetheless successful points to the simplicity of the soil problems we have been addressing up until now. As we are challenged to better understand the energy dynamics of the earth, this is certain to change.

ref: C. C. Nikiforoff. 1959. "Reappraisal of the soil: Pedogenesis consists of transactions in matter and energy between the soil and its surroundings". Science 129: 186-196.

Hephzibah Sludge

Been following the sludge story from Hephzibah, Ga.? If you work in support of biosolids, like I do, you should be.

Andy McElmurray, a farmer in Hephzibah, Ga., fed his dairy cows silage that had been fertilized with sewage sludge laced with heavy metals. More than 300 of them died.

In February, a federal judge ordered the Department of Agriculture to compensate McElmurray for losses incurred when his land was poisoned between 1979 and 1990 by applications of Augusta, Ga., sewage sludge. That sludge contained levels of arsenic that were two times higher than EPA standards allow; of thallium (a heavy metal used as rat poison) that were 25 times higher; and of PCBs that were 2,500 times higher.

What's more, milk from his neighbor's dairy farm was sent to market with thallium levels 120 times higher than those allowed by the EPA in public drinking water.

In his ruling, U.S. District Judge Anthony Alaimo was particularly critical of the EPA and the University of Georgia for having endorsed "unreliable, incomplete and, in some cases, fudged" data about the Augusta sludge. That corrupt data was presented to the National Academy of Sciences, which then cited it in their July 2002 assertion that sewage sludge does not pose a risk to public health.

Alaimo wrote, "Senior EPA officials took extraordinary steps to quash scientific dissent, and any questioning of EPA's biosolids program."

Our biosolids have incredible fertilizer value in terms of phosphorus and nitrogen, which is what pulls me into the mix. But it is valuable only to the degree that it can be trusted. Some biosolids can be trusted, some cannot. Let's do this thing, people.

Make dirt more better

Soil has a problem. It is eroding faster than it is being made. That's a given in these times of relative geologic stability. Most soil was formed in depositional material. Without sedimentary deposits being exposed by tectonic processes, without substantial volcanic ash fall, without the continental glaciation producing silt, and without the global wind storms and cataclysmic post-glacial flooding to redistribute that silt, we basically have to wait on the next climate change re-boot for our next era of major soil replenishment. In these trying times on the downhill slide from peak soil resources, we'll have to make better soil from the soil that we have left.

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)

Stop Polluting My Biosolids

We would be well served if we stopped manufacturing unnecessary body soaps and scents. They end up in sludge, er biosolids and, as is necessary, on the land, where they can have unintended consequences. Let's just stop manufacturing the offending molecules.

Home Buyers Will Pay for Soil, Won't Pay For Dirt

In 2003, the Snohomish County Public Works Department published a remarkable manual with a simple title: Building Soil (pdf). Promoting sediment-free stormwater, it encouraged builders to embrace the wisdom of retaining native soil and vegetation, and to question the value of turning soil into dirt for no good reason. From a building perspective, soil is a valuable construction material manufactured from a low cost/ low value soil resource feedstock. The thinking goes like this: Manipulating soil tidies up a site and adds value. Stormwater regulations interfere with the ability to add value, thus the disconnect.

Enter the Washington Organic Recycling Council which has a new site, www. buildingsoil.org, with a new and refreshingly non-regulatory spin for convincing builders to buy into the principles in the Building Soil manual. The pitch goes like this: Avoiding disturbance around the building footprint, in a sense, doing nothing, confers a marketable value on that soil resource.

New home buyers say they are happy to pay more for a healthy, easy to care for landscape – and that starts with the soil.

A timely message in a buyers' market.

Why is HIV so prevalent in Africa?

... asks Melinda Wenner. Geographer Harold Foster is convinced that it is due to low soil selenium levels. Selenium is mobile, prone to leaching as well as accumulation. Health-wise, it is one of the more interesting elements. Reputed to be an immune system stimulant, yet it is notorious for accumulating in plants and soil to a toxic degree.

Sub-Saharan Africa, with 96 percent of all AIDS cases, has a wide variety of soil types (see soil map provided) but which generally have low soil selenium.

Senegal has a significantly lower level of AIDS infection than the rest of sub-Saharan Africa. It also has uncommonly high soil selenium.

Foster's most recent article is pay walled by Elsevier, but the abstract is certainly intriguing:

The global diffusion pattern of HIV/AIDS is strongly suggestive of a protective role for the trace element selenium. It is hypothesized here that the body's antioxidant defense system, especially the selenoenzyme glutathione peroxidase, acts as an initial defense against viral infection, preceding the formation of antibodies. [emphasis added] For this reason, HIV is having its greatest difficulty in infecting those with diets elevated in amino acids and the trace element selenium which, when eaten together, stimulate the body's production of glutathione peroxidase.

One selenium link to AIDS is well established: A low selenium blood level of selenium among HIV/AIDS infected patients is associated with high AIDS-related mortality. Foster has been writing about this for some time in terms of treatment.

Since this virus encodes for glutathione peroxidase, as it replicates it deprives its host of selenium, cysteine, glutamine and tryptophan, eventually causing severe deficiencies of each in HIV-1 seropositive individuals. AIDS is the end product of these declines and the majority of its symptoms are caused by these deficiencies. Selenium and cysteine inadequacies, for example, undermine the immune system in a process that is accelerated by other infectious pathogens. A deficiency of glutamine promotes muscle wasting and digestive malfunction, while a lack of tryptophan and the compounds it biosynthesizes (such as niacin and serotonin) causes dermatitis, diarrhea and various neurologic and psychiatric symptoms including dementia. It is also clear from the literature that supplementation relieves these symptoms and would, therefore, appear to be the most logical treatment for AIDS. The major aim of this treatment would be to return body levels of selenium, cysteine, glutamine and tryptophan to normal. The evidence suggests that this would greatly reduce HIV-1's ability to replicate. Doses, therefore, would vary with the disease stage. It also is probable that niacin and serotonin would prove beneficial.

One double-blind, randomized, placebo-controlled trial has solidly confirmed the ability of 200 micrograms (μg) a day of bioavailable selenium to significantly affect viral load among AIDS patients. That is certainly good news and confirms selenium as a viable treatment.

Foster has now advanced beyond treatment into an area likely to be far more controversial: He is saying that, in low selenium soil regions, dietary selenium can reduce the risk of infection and rate of spread of the AIDS virus between individuals. The world hopes that he is correct.

Soil conference on non-CO2 gas emissions

Researchers at the University of Melbourne are holding a conference to discuss the importance of greenhouse gas emissions from soils.

A major concern is nitrous oxide from fertilizer, manure and biomass applications.

"300 times more potent than CO2, so even small emissions of this non-CO2 gas can make a considerable contribution to global warming” says Dr Stefan Arndt.

“When nitrogen is added to a wheat field as fertilizer or added to a pasture through animal faeces or clover swards, a part of the nitrogen can be lost as nitrous oxide, and when the weather conditions are right this can lead to large emissions of nitrous oxide” says Dr Eckard.

...not widely known [is] that soils can actually [take] methane out of the atmosphere. “Forest soils are especially efficient at taking up methane” says Dr Livesley.

At the present time there is not much knowledge about the magnitude of these non-CO2 emissions...

(revised May 18, 2007:)It is interesting that non-CO2 GHGs, like nitrous dioxide (NO2), aren't more in the news, considering their potential impact and (for NO2) a fascinating pattern of anthropogenicity.


Image source: Greenhouse gases, by Anyday.se

edit: revised intro to N02 map - yet again as my level of understanding evolves

Soil is a living system.

Like Snow
Originally uploaded by bones4.

Soil behavior fundamental to soil performance requires a living component. Remove the life from soil and it can be argued that what remains is no longer soil. It remains not-soil until it is reinoculated, repopulated, and restored to a living system. For all but the harshest land surfaces on our planet, soil life "reboots" faily easily.

Other names consistent with not-living "soil" are dirt, regolith, buried soil, and soil fossil. Another term, earthen material, encompasses both soil and not-soil.

An interesting discussion is whether there can be lunar soil or martian soil. While life currently appears absent, the surface of lunar and martian regolith does appear to have been sufficiently transformed by solar energy flux to qualify as a candidate soil. Since life is all about energy flux, perhaps our current concept of soil as a living system will ultimately be replaced with a concept of soil as an energized system.

Reposted from Yahoo Answers.

Triclosan Update

I've posted on my concern for triclosan-containing products before. I think far too much of it is being land applied in our biosolids:

It makes little sense to land apply recalcitrant compounds that needlessly get rid of soil microbes. Fomenting the growth of resistant strains of disease organisms is only one concern. Soil functional capacity is largely mediated by living processes. It is the height of folly to jeopardize those functions for a useless consumer item.

How much effect does it have on biosolids-applied soil? Probably it is only slight at any given site. It is the total mass involved and the extent of the impact that has me uncomfortable.

Being soil-aware, I have also come to appreciate that our skin, like soil, hosts a diverse population of bacteria that when in balance, works in our favor. Part of our disease protection comes from that community. If we kill off the easy ones, we are left with the toughs who can now move into the colonization sites left vacant. That's how it works on the skin of the earth, anyway. I'm not saying that we should avoid washing our hands, just that acting on simplistic thinking can expose us to risks greater than the ones we act to avoid.

For example, the latest concern with triclosan use is that when exposed to warm (100 deg F) tap water containing chlorine, a common scenario for use, it breaks down after less than a minute of exposure. The breakdown products include chemicals of concern to skin care including chloroform. This may better explain reports that triclosan-containing products induce dry skin, eczema, and, under conditions of high use (20-25 times per day), open sores. Open sores and a tough crowd of bacteria is not a good combination.

This observed rapid breakdown of triclosan does not negate previous observations of recalcitrance in the treatment process, in the soil, and in our waterways. The wastewater treatment processes that produce biosolids do not employ chlorine, or any equivalent chemical oxidizing agent. To shock the process with chlorine would kill the bugs doing the work.

I am sure there are some good uses for triclosan. Maybe a place in the acne control tool box is one. The majority of this product is sold for normal household use. The casual use of triclosan needs to end.

Image Source: Neil Duazo

Hypography Science Forum Upgrades Terra Preta Discussion

The Hypography Science Forum has upgraded the terra preta discussion from a long, 43 page thread to a forum, with separate threads for charcoal making, gardening experiences, news, etc. The new location is here.

A recent message posted to the forum, from Janice Thies, Cornell University, is most interesting:

I am extremely heartened by the very positive response to the idea of using of biochar in agriculture and horticulture and appreciate your desires to put it to immediate beneficial use in these systems.

My name is Janice Thies. I am a soil microbial ecologist. I have been working with Johannes Lehmann at Cornell University for the past 6 years on various aspects of terra preta (microbial ecology in its natural state) and agrichar (how microbial populations respond to adding biochar to soil). It took us three years to convince the National Science Foundation that we were on to something here and to obtain funding for some of the basic research that is necessary for us to provide the data needed to answer your questions with confidence. Hence, we are several years behind where we could have been if funding had been available earlier. Even now, we continue to seek support for doing the types of tests many of you are most interested in. The results of our NSF funded research are just now being published or written up, but we are still a long way from being able to answer everything.

Currently, there are 10 research laboratories around the world that are testing char made from bamboo that was prepared at 5 different temperatures in the range we believe is likely to provide char that will be most beneficial for both plant production and C sequestration purposes. Rob Flannigan prepared the char in China and has engaged us all to do a wide range of testing on it. So, we should have some news about what temperature range might be best reasonably soon, but it is still early days.

Bio-char amended plots respond more favorably if adequate nitrogen fertilizer is provided. This is consistent with a previous observation here that added nitrogen is desirable when increasing soil microbial biomass.

One of the reasons that Dr. Lehmann recommends caution in the use of biochar can be seen in the paper recently published by Christoph Steiner et al., mentioned in previous messages. He did get excellent plant growth responses to adding biochar - as long as mineral fertilizer was also used. When you look at plant growth in the biochar only treatment, growth was worse than doing nothing at all (check plots). In the nutrient-poor and highly leached soils of the tropics, the added biochar likely bound whatever nutrients were present in the soil solution and these became unavailable for plant uptake. These results should make you cautious as well. How fertile a soil needs to be for biochar not to reduce plant growth or exactly how much fertilizer and/or compost should be added to be sure there is good, sustained release of nutrients, will likely vary soil to soil and we simply do not have these data available at present to make proper recommendations. So, keep this in mind as you do your own trials with your own soils or mixes. Try to follow good design practices for your trials, with replicates, so that you can judge for yourself what amount and type of biochar works best in combination with what amounts and types of fertilizers or composts you use (depending on the philosophy behind your cultural practices).

The soil microbial community in terra preta is different from that of surrounding soils, yet is repeatable over great distances. Actinomycetes bacteria seem to have a particular affinity for terra preta.

As to the 'wee beasties' or 'critters' as I like to call them, we have made progress on this front over the last several years. Brendan O'Neill and Julie Grossman in my laboratory, Sui Mai Tsai, our Brazilian collaborator at CENA and the University of Sao Paulo, and Biqing Liang, and many others in Johannes Lehmann's laboratory have been characterizing microbial populations in three different terra preta soils and comparing these to the adjacent, unmodified soils near by to them. Brendan found that populations of culturable bacteria and fungi are higher in the terra preta soils, as compared to the unmodified soils, in all cases. Yet, Biqing found that the respiratory activity of these populations is lower (see Liang et al., 2006), even when fresh organic matter is added. This alone means that the turnover of organic matter is slower in the terra preta soils - suggesting that the presence of black C in the terra pretas is helping to stabilize labile organic matter and is itself not turning over in the short term. All good news for C sequestration. However, since the respiratory activity is lower (slower decomposition), this may lead to slower release of other mineral nutrient associated with the fresh organic inputs. In some circumstances this is a good thing (maintaining nutrient release over the growing season), in other circumstances (more immobilization), perhaps not. We need more work on this to understand the implications of these results more fully.

Julie Grossman, Brendan O'Neill, Lauren McPhillips and Dr. Tsai have all been working on the molecular ecology of these soils along with me. So far, what we know is that both bacterial and fungal communities differ strongly between the terra pretas and the unmodified soils, but that the populations are similar between the terra preta soils. These results are both interesting and encouraging. First, that the terra preta soils (sampled from sites many kilometers apart) are more similar to each other than to their closest unmodified soil (sampled within 500 m) tells us that the conditions in the terra pretas encourage the colonization of these soils by similar groups of organisms that are adapted them. Our group has been working on cloning and sequencing both isolates from the terra preta soils and DNA extracted directly from them. A number of bacteria that were isolated only from the terra preta soils are related to the actinomycetes, but have not yet been described yet and are not very closely related to other sequences of known organisms in the public genetic databases. This is also very interesting. Some of you will know that actinomycetes have many unusual metabolic capabilities and can degrade a very wide range of substrates. Also, many are thermophilic and play important roles in the composting process. We have yet to fully characterize these organisms, but are optimistic that in time we can make some recommendations about what organisms or combinations of organisms might make a good inoculant for container-based biochar use. Two papers describing these results are in their final editing stages and will be submitted for publication in the journal 'Microbial Ecology' within the next few weeks. So, keep an eye out for them in several months time.

The prospect that glomalin might play an important role in terra preta needs to be approached with caution.

I want to add a word of caution about getting too excited about glomalin. Another of my students, Daniel Clune, has been working on this topic and his work suggests that the glycoprotein referred to as 'glomalin' in the literature - operationally defined as the protein extractable in a citrate buffer with repeated autoclaving - is not what it has been purported to be. First, the proteins extractable by this method are from a wide range of sources, not just arbuscular mycorrhizal fungi. Second, it has a shorter turnover time than has been suggested. Third, in a test with hundreds of samples taken from field trials varying in age from 7 to 12 to 34 years, its relationship with aggregate stability is suggestive at best. Dan's work is also being written up right now and should also be submitted for publication soon.

Could archaea be important?

Some field trials with bamboo char have been conducted in China, with very positive results. Look for upcoming papers from Dr. Zheng of the Bamboo Institute in Hangzhou. Another student in my laboratory, Hongyan Jin, is working with the soils from this experiment to characterize the abundance, activity and diversity of the soil bacteria and archaea. Her first results will be presented at the upcoming conference on Agrichar to be held in Terrigal, NSW, Australia, at the end of April/beginning of May this year. Please be sure to see her poster should you attend this conference.

Janice's recipe for char based potting soil:

Lastly, from my personal gardening experiences, I use spent charcoal from the filters of the 14 aquaria I maintain for my viewing pleasure. I combine it as about 5% of my mix with 65% peat moss, 10% vermicompost (from my worm bin in my basement where I compost all my household kitchen waste - aged and stabilized, not fresh!), 5-10% leaf mulch (composted on my leafy property in NY), 5-7% perlite to increase drainage, decrease bulk density and improve water retention and percolation, and some bone meal and blood meal (to taste :-) ). This makes an excellent potting mix for my indoor 'forest'. I am very much still playing around with this.

I hope this very long posting helps those of you feeling frustrated and wanting answers. Many labs are working on many fronts, but it is early days and we are trying to answer some fundamental questions first and then use the information to guide our field tests and recommendations.

I hope to meet some of you at the Agrichar Conference (see details at the conference website) http://www.iaiconference.org/images/IAI_brochure_5.pdf
The Cornell work and that of many of our colleagues in Brazil, China, the US, Australia and elsewhere will be presented, along with that of many others actively working on agrichar production and use around the world.

Good luck with your own testing and kind regards,

Janice Thies - jet25 at cornell.edu
719 Bradfield Hall, Ithaca, NY 14853

Technorati Tags: terra preta archaea bacteria soil microbiology bio-char garden glomalin

Soil Collapse Conditions Illegal, Preventable

In the previous post, Don't Dig Too Deep, I wrote of the alarming extent of death and injury related to soil collapse. Historically there have been 100-300 deaths a year in the US due to soil collapse. One would hope that the current level is far lower, since these deaths are preventable, and the conditions that cause them are largely illegal to send workers into. News coverage of trench collapse is often cavalier when it reports survival, celebrating a can-do attitude and sidestepping a duty to inform. News readers deserve to be told how extensive the problem is, industry standards, or how they can take simple steps to avoid future injury to themselves and their loved ones.

Injuries that occur in the workplace deserve to be covered in the news from the point of view of compliance and employer ethics. All news coverage I have ever seen on these tragic work-related events leave off the preventable and illegal aspects of the event. The story in Georgia that prompted my post was no different.

Jordan Barab has been posting on this issue with the news media: trench collapse should not be treated this lightly; most workers do not come out alive.

Soil collapse is quiet and quick. Soil goes from supported to free fall in an instant. A collapse event initiates with little or no warning to a trench occupant. It is loudest at the end of the collapse event, yet seldom heard beyond the immediate area of the trench. Unless it is witnessed directly, or the victim can make themselves heard, a rising cloud of dust is the only evidence available to alert coworkers to respond.

A discrete soil collapse event is normally progressive in nature. First an uppermost portion of a trench wall caves off, and drops straight down like a slice off a block. When I am in a trench, even a shallow one, I am ever vigilant for this first increment. Falling from the maximum height it is moving fairly fast by the time it reaches the trench bottom. In injury events, it typically traps the feet and prevents trench egress. The collapse progresses to involve soil volumes coming from further down the wall and further back: lower velocity but far more weight and volume than the first increment. The progression commonly ends with a maximum increment.

This leaves remaining vertical wall sections unsupported at the margins of the collapse. Subsequent collapse of these vertical sections is a substantial hazard for rescue workers. 60 percent of fatalities in trench rescues involve would-be rescuers.

OSHA standards require trenches deeper than 5 feet to be shored. Shallower trenches can still be the site of fatal soil collapse, especially if workers are not standing upright. Movable temporary shoring is available within the construction industry. An alternative is to excavate sloping or terraced sidewalls. Due to vibration, heavy equipment should not be left running in proximity to occupied trenches. Interior trench corners are particularly susceptible to collapse and deserve particular caution.

Technorati Tags: soil hazard safety

Don't Dig Too Deep

Historically, there have been between 100 and 300 people killed in the United States every year due to trench collapses. Jordan Barab covers these trench hazards in his worker safety blog, Confined Space.

On Friday, a worker in Georgia was trapped for two hours, briefly up to his neck, when the trench he was working in collapsed. Last word was that he survived, but the extent of his internal injuries had not been assessed. He is in my prayers.

It is a strong man, and lucky to boot, able to breathe under the crushing dead weight of soil. When soil drops, it quickly gains sufficient momentum to slam the air out of most folks. Against the weight of soil, there can be no place to expand the lungs. Even a person buried below his chest may still be grave danger. Where the soil reaches the diaphragm level, and settles in a form that has pushed the abdominal contents into the chest cavity, the effect on breathing can be the same as confining the chest.

Soil walls may collapse multiple times, or in phases, in the same trench. 60 percent of fatalities in trench rescues involve would-be rescuers. Soil collapse related deaths are both work-related and recreation-related, and all too often include children. The beach is a repeated setting of concern (from a story apparently no longer up at WebMD):

Safety Note for Beachcombers: Don't Dig Too Deep

Sand Holes Collapse, Suffocate Toddlers, Children, Even Adults

By Jeanie Davis
WebMD Medical News

Reviewed by Dr. Jacqueline Brooks

April 17, 2001 -- Sharks, skin cancer, drowning -- was a day at the beach ever a picnic? What's left, just digging holes in the sand? Maybe not. With beach season drawing nearer, two researchers report that several children -- and young adults -- have died when sand holes got a bit too deep and suddenly collapsed on them.

“There actually is the potential for catastrophe," says Bradley A. Maron, a second-year medical student at Brown University School of Medicine in Providence, R.I. The paper, which he co-authored with his father, Barry J. Maron, MD, of the Minneapolis Heart Institute Foundation, appears in this week's Journal of the American Medical Association.

In their paper, the Marons document seven cases of sudden- and near-death experiences involving beach holes.

The Marons' study began four years ago -- during a vacation at Martha's Vineyard -- when they witnessed a beach-hole incident that triggered their study of the phenomenon. "It was an 8-year-old girl, under the sand for seven minutes before rescuers could get to her," he tells WebMD. She survived, says the younger Maron.

He spoke with the beach rescue team afterward: "They said without question it seems to happen with greater frequency than is realized," Maron tells WebMD. He began watching CNN for similar news accounts and made follow-up phone calls for details.

Six of the seven incidents he documented since 1997 took place on public beaches -- all on the Atlantic coast -- mostly involving children, says Maron. In five cases, the holes were being dug by hand or using toy beach shovels. In two instances, people were inside holes they had found.

In each instance, Maron says, the person suddenly became completely submerged by sand when the walls of the excavation unexpectedly collapsed.

"The biggest complication in rescue efforts," Maron tells WebMD, "is that the sand appears undisturbed after the hole caves in, so rescuers don't know exactly where the person is. And they have to dig with their hands, for fear of hurting them with shovels. They just can't get to them in time." Four people among the cases were submerged for long periods of time -- 15 minutes to an hour -- and could not be resuscitated.

In one case, a 21-year-old man vacationing in North Carolina dug a nine-foot-deep hole. "He was down in the hole, just lounging in the chair when suddenly and unexpectedly it collapsed on him," says Maron. "It was catastrophic immediately. He had to be removed by bulldozer." Rescuers attempted CPR, but the man died.

Three people survived -- including one who experienced hypothermia and shock -- after lifeguards or other bystanders frantically dug an air pocket around their mouths and noses.

"Parents feel safe with their kids right by their side," Maron tells WebMD. "But they may not be attuned to what's going on. And afterward, people are so shameful of themselves. Of course it's not their fault; it's an accident, but it's absolutely preventable. It just takes common sense."

This phenomenon was news to at least one beach rescue team member, but he's not surprised.

"A lot of times you see kids digging up to waist deep, and that can be just as hazardous as head-deep," says Sean Gibson, a paramedic with New Hanover Regional Medical Center, which services the beaches in Wilmington, N.C.

"A cubic foot of sand weighs much more than you would think, and there's no way that child could get out," he tells WebMD. "And nobody would be able to hear that child either."

Adults should know better than to take the risk, says Gibson. And parents should be watching their children more closely. But if children do get into this situation, here's good news. "With toddlers and children, you should be able to get to them fairly quickly if you see it happening."

Although sand dunes don't exactly fall under the Occupational Safety and Health Administration's jurisdiction, OSHA certainly recognizes trenches of all shapes and sizes as hazards, says H. Berrien Zettler, deputy director for construction.

OSHA has investigated 24 fatalities resulting from cave-ins in the last year alone, he tells WebMD. "It's a serious issue. People don't realize that dirt, or sand for that matter, is extremely heavy. It makes it impossible for people to exercise their abdominal muscles to draw in air; essentially, they suffocate."

The sheer weight of sand causes the collapse, says Zettler. "And people don't have to be completely covered with it to suffocate. Chest deep could be enough to do it -- you just can't draw air. If you're sitting down, it takes even less -- just two or three feet of sand -- to cover your chest."

Although wet sand looks hard, it's actually extremely unstable, because nothing is holding it together, says Zettler. "There's no cohesion like you find in clay soil. You dig into it, and it's like a liquid."

Be careful out there. Keep an eye on our children.

Technorati Tags: soil blog hazard safety

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

Technorati Tags: soil microbiology carbon analysis

Home Grown Biofertilizer

The role that soil microbes (archaea, bacteria, and fungi) play in soil nutrient availability is an interesting area, one where we have much to explore. Biofertilizers are increasingly available commercially, meaning those of us outside the academic community will have increasing opportunity to conduct our own reseach. From Montana State University:

Some soil bacteria and fungi can access otherwise unavailable phosphorus, and some are commercially available. In a study on barley, one of these bacteria increased phosphorus availability by about 10 percent. In another study, a phosphate-solubilizing fungus was found to increase spring wheat grain yield by nine percent. "For both studies, the economics need to be considered to determine if these increases are worthwhile, and additional research is needed to determine the effectiveness of these products for different crops and soils," Jones said.

Growing your own biofertilizer may not be that difficult, depending on what it is you are trying to grow. Pictured is some compost tea starter I am "growing" for tomorrow's 36 hour run of actively aerated compost tea. I am going for a fungi-rich tea. Since the aerated tea process favors population growth of bacteria (and, one would think, archaea) over fungi, I am giving the fungi a boost before I start the tea. To 2 cups of compost, I have mixed in 3 tbs oat bran (the white flecks) and 1 tsp of T and J Enterprises (Spokane, WA)'s trichoderma rich "Soil Life & Activator" mix. As you can see the fungi is doing mighty fine. My first couple runs at promoting fungi growth were not as successful. By the looks of this one I am starting to get the hang of it.

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My Interesting Experience With Biosolids

It's May 5, 2005 on a biosolids research plot somewhere between Kennewick WA and Umatilla OR . If you can use either a link to Google Maps or a Google Earth kmz file, the plots start 250' S, 150' E of the fence line and extend to 650' S, 425' E. The aerial photos Google has up as I post this were evidently taken before our field visit, probably in late winter (January?) 2005. The dark E/W swaths Google shows would be annual ryegrass (Lolium multifloruminvasive winter rye (Secale cereale) growing better than normal in areas which received aggressive application of municipal biosolids. Application was in April, 20042003.

The fellow in the distance is Tom Duebendorfer (Elmira, ID), botanist extraordinaire. Tom is carrying the quadrat to the west end of the application swath south of the one I am in. I am following about 20 minutes behind him. The wire flags (pink) are randomized sample points down the middle of the application swath. That's my soil sampler in the foreground, a Viehmeyer probe. It's a lot easier to get in than it is to get back out. The astute observers among you will have already noticed that the grass in the plot isn't looking so good: it is thick, brown and stubby whereas Tom is walking in a taller but thinner stand of green grass.

The biosolids killed the grass, but how? My thinking is that it is not a simple toxic effect. Impaired growth or necrosis would have expressed itself soon after the April 20042003 application, or prevented stand establishment at the beginning of the 2004 and 2005 season. Instead we had brief lush growth, almost like a growth hormone effect. 2,4-D works that way, but not on grasses.

My conclusion is that the effect is due to abundant nutrient availability and complex weather patterns unique to 2005. The application rate was designed to promote biomass gains. It worked, and as a result, the grass grew lush and depleted the soil moisture. With abnormally low rainfall in March, by April it had run out of moisture and had to close up shop for the year. April rains came too late for this brown grass, but helped relieve drought stress in the normal areas.

Soil nitrate levels were elevated in the brown areas but not to an alarming degree. Tom didn't see any application affect on the plant species composition, but then we have not formally analyzed the data. Composition effects are probably going to occur after 2005, beyond the scope of the study. I expect we would see an increase in annual ryegrassinvasive winter rye at the expense of other species.

Look close and you will see the ryegrass was still able to produce a fair amount of seed. L. multiflorumS. cereale is an invasive species, and was the only component in the system that really seemed to benefit from the aggressive biosolids rates to a degree that increased it's longterm competitive potential. I can think of any number of invasive species that would respond similarly.

As an aside, it is unlikely that Tom and I will be preparing a formal report based on the data. The sludge hauling client went bankrupt shortly after that May 2005 sampling. The study was a condition of satisfying a permit violation. Outside of that original context, it falls off both our urgency/importance project matrices.

Corrections: Application was in 2003, not 2004. Ryegrasss is winter rye, secale cereale, not annual ryegrass lolium multiflorum.

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The Smell of Healthy Soil

Actinobacteria are a hyphae-producing soil bacteria that, in appearance and behavior, appear to have more in common with soil fungi. Like fungi, they decompose some of the more resistant forms of organic plant residues. Like fungi, they form branching filaments, which resemble the mycelia of fungi. Actinobacteria were originally classified as fungi under the older name Actinomycetes.

As bacteria, Actinobacteria have cell walls. They grow best in soil when conditions are damp and warm, playing an important role in decomposition of organic materials, such as cellulose and chitin. When the soil dries they produce spores. The wetness and force of rainfall kick these tiny spores up into the air. The moist air easily carries the spores to us so we breathe them in. These spores have a distinctive, earthy smell we often associate with rainfall. The smell comes from a compound, geosmin, which translates to "earth smell". The human nose is exquisitely sensitive to geosmin, able to detect it at concentrations down to 10 parts per trillion. Since the bacteria thrives in moist soil but releases the spores once the soil dries out, the smell is most acute after a rain that follows a dry spell, although you'll notice it to some degree after most rainstorms. Actinobacteria are important to healthy soil function, and are ubiquitous. Thus the smell of healthy soil is similar the world over.

Though they play an important role in soil quality, Actinobacteria are more commonly known for what it produces in the laboratory. Actinobacteria are unsurpassed in their ability to produce many compounds that have pharmaceutically useful properties. In 1940 Selman Waksman discovered that they made actinomycin, a discovery for which he was awarded a Nobel Prize. Hundreds of naturally occurring antibiotics have been discovered in these terrestrial microorganisms, especially from the genus Streptomyces.

Actinobacteria are also involved in nitrogen fixation; they convert atmospheric nitrogen into a form that can be used by plants.

Photo source: the earth smells good
Originally uploaded by kamalawalabear

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Triclosan, Triclocarban Concern

Triclosan and triclocarban are small organic molecules that give antimicrobial properties to personal-care products such as soap, deodorant and toothpaste as well as durable goods such as cutting boards, baby carriers and socks. The environmental persistence of these compounds is remarkable. More than a million pounds of these chemicals flow into the nation's sewers every year. Recently improved laboratory analysis demonstrates that 50 percent of triclosan and 76 percent of triclocarban remain unchanged by aerobic and anaerobic digestion in a typical wastewater facility, where most of it is retained in the solids fraction. We can assume that the same can be said of breakdown in the septic systems that 25% of us use in the USA. Most of these solids get spread on land to fertilize pasture, forest, biomass, fiber, feed and food crops.

Triclocarban has been determined by the FDA as having no verifiable benefit. Despite a lack of evidence that these compounds accomplish anything beneficial, usage rate is very high among consumers. Among the households I have surveyed, it approaches saturation.

It makes little sense to land apply recalcitrant compounds that needlessly get rid of soil microbes. Fomenting the growth of resistant strains of disease organisms is only one concern. Soil functional capacity is largely mediated by living processes. It is the height of folly to jeopardize those functions for a useless consumer item.

US-EPA, which has oversight on land application of biosolids, is studying the situation. More work is needed, but everyone writing on this issue seems to get it: this is not an arrangement that we want to sustain.

Sources: (1), (2), (3), (4), (5), (6)

Update: The American Medical Association took an official stance against adding antimicrobials to consumer products in 2000 and has repeatedly urged the Food and Drug Administration (FDA) to better regulate these chemicals. (Source)


Photo: hand sanitizer
Originally uploaded by chewywong.

Technorati Tags: soil science biosolids microbiology health