Indicator of Reduction in Soils (IRIS)

The list of activities and structures that don't do so well in reduced conditions is pretty long: septic drain fields, crops and steel underground storage tanks come to mind. On the other hand, reduced conditions are a requirement for jurisdictional wetland designation and constructed wetlands. Beyond that, watching the playoff between various redox gradients in soil is just plain fun.

Pedology and Wetland Soils

Development and Evaluation of Iron-Coated Tubes that Indicate Reduction in Soils

B. J. Jenkinson and D. P. Franzmeier^*

Dept. of Agronomy, Purdue Univ., Lilly Hall of Life Sciences, 915 W. State St., West Lafayette, IN 47907-2054

^* Corresponding author (dfranzme@purdue.edu )

Soil drainage conditions are important to land use decisions. Traditionally, anaerobic conditions induced by poor drainage have been evaluated by observing soil color related to Fe and Mn oxides, using , -dipyridyl dye, measuring dissolved O₂, and measuring E_H. We believe that there is further need for a device that is scientifically sound and easy to use. Therefore, our goals were to develop and test a device that mimics natural soil processes, visually indicates soil reduction, and is robust. Our concept was to coat a rod or tube with a colored soil mineral that dissolves on reduction, insert the device into a soil, remove it after a few weeks or longer, and observe if some of the coating had been lost. If the coating was not dissolved, no reduction occurred, but if it was dissolved, reducing conditions must have prevailed. After trying several kinds of coatings and tubes, we chose ferrihydrite (FH) coating on polyvinyl chloride (PVC) pipe. We call the device an Indicator of Reduction in Soils (IRIS). As the study progressed we added semi-quantitative interpretations by measuring depleted areas using a digital camera and image analysis. We tested IRIS tubes in the lab and in soils in Indiana, Minnesota, and North Dakota, and concluded they performed as expected. Reduction rates increased between February and April and were related to increasing soil temperature, turnover (flux) of soil OC, and content (inventory) of OC. Reduction rates decreased after April, presumably because the nutrient supply for microbes decreased.

Abbreviations: Ac, area of FH coating in contact with the soil • Ad, area from which some FH had been depleted • D, percentage of Ac from which some FH had been depleted • DO, dissolved O₂ concentration • FH, ferrihydrite • IRIS, indicator(s) of reduction in soils • OC, organic carbon • PVC, polyvinyl chloride • UDD, upper depth of FH depletion

Easy and straightforward. Kind of like the traditional sticking of the toothpick into the banana bread to see if it's done.

Note: I updated this article a few hours after posting the original. If you read the first version, my sympathies. What can I say. Its a gift.

Further Reading:
Redoximorphic Features Powerpoint presentation developed by: Michael Whited, USDA-NRCS - Wetland Science Institute August, 2000. (4.6 MB) (source page )

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In Praise of Richmond Bartlett

“We all should fall upon our knees and sing out praise for manganese.�
Richmond Bartlett (wikiquote)

I received the following from Paul Bloom earlier today.

Below is an announcement supplied by Don Ross of the University of Vermont. I truly enjoyed the times I got to sit and discuss life and science with Rich. He was as unique character, but more that he was a good scientist and a fine human being.

Paul Bloom

Richmond Bartlett died Tuesday, December 20 at the age of 78. His contributions to the field of soil chemistry were many and he will be missed. He would surely want everyone to remember the difference between soil and dirt, and the fact that manganese can explain everything (almost). There are plans for a memorial service on Saturday January 7th on the campus of the University of Vermont in Burlington, time and place to be announced.

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Phosphorus and TMDL

Today I am pulling together conceptual information related to phosphorus (P) and Total Maximum Daily Load (TMDL) in anticipation of meeting with Walt Edelen and Rick Noll, water quality folks with the Spokane County Conservation District (SCCD). The problem we will be putting our heads together on is the relationship between river and stream P levels (ug/l) relevant to TMDL and soil P levels (mg/kg) in adjacent, contributing areas. More specifically, we are going to lay out what methods and approaches are available for gathering soil P information that will produce data that can be used to measure P loading, measured in pounds of phosphorus, lost to the river. We want tools to quantify the effects of implementing various Best Management Practices (BMPs) for controlling streambank sluffing and farm field erosion.

The motivation for specifically defining pounds of phosphorus delivered has to do with the concept of phosphorus load allocation. It has to be conceptual, rather than actual, because, when it comes to soil contributions, we don't have the studies needed to characterize the complex causes and effects in these systems. Nor do we have the luxury of time of waiting for the studies to be designed, funded and conducted. The TMDL beast is at the door.

At first glance, it seems like a simple question of mass balance. How many tons of soil are discharged to the river, where and when, and how much phosphorus did it have in it. A mass balance approach certainly makes sense for wastewater dischargers, considered the most significant source of P in the Spokane river. But that approach doesn't fit as easily for soil. How much soil phosphorus converts to water phosphorus. It can't be 100% efficient, some will end up dissolved in the water, some will end up involved with the suspended sediment load but the rest will end up on the stream bottom where it will contribute P to water only over a long period of time. Complicating this is seasonal changes in capacity of a stream to carry suspended sediment. Clean water is hungry water and it picks up material fairly easily. Muddy water is different and it drops it's sediment load whenever it loses energy, the insides of curves for instance. You can bet that sediment delivered to a clean stream is going to affect total phosphorus levels more efficiently than sediment delivered to a muddy stream. Considerations of efficiency mean testing for available phosphorus may not be enough. The next most obvious analytes to add into the mix are total phosphorus, texture, pH and organic matter content. I'm looking forward to a lively discussion.

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Dept of Licensing Surveys Soil Science Practice, Recommends Regulation

The Washington State Department of Licensing (DOL) has submitted a requested Sunrise Review of Soil Scientists to the State House Commerce & Labor Committee. The report recommends that the practice of soil science be regulated.

Members of the Washington Society of Professional Soil Scientists (WSPSS) can find much to be proud of as well as cause for renewed vigilance in DOL's report. Soil science has been in DOL's sights before but the current set of events that led to the sunrise report started in 2001. That was the year that soil scientists became concerned that under the Geologists Licensing Act, practicing soil science would require being a registered geologist. Timely action by WSPSS resulted in an exclusion for the practice of soil. It also reignited WSPSS' interest in licensing.

Renewed efforts followed shortly in 2002 when soil reports prepared by a soil scientist were rejected by the Pierce County Planning Department. The planning department required a licensed geologist, consistent with a draft model Critical Area's Ordinance (CAO) being prepared by the State Department of Community, Trade & Economic Development (CTED). Subsequent effort by WSPSS to revise CTED's Model CAO to include soil scientists as qualified to submit soil reports were initially successful but, for reasons that have not been determined, the soil science profession was not included in the final draft.

Without licensing, soil scientists are failing in their efforts to maintain their professional standing with county planning departments, health districts and permitting agencies in Washingtonm State. Draft legislation to license the practice of soil science was submitted to both State Senate and House committees during the 2004/2005 legislative session. Lobbying efforts resulted in the House Commerce & Labor Committee request to the Department of Licensing to prepare a “sunrise� report that would define the reasoning and metrics underlying the request to be regulated.

An excerpt from that report:

Considerable evidence compiled in this report, through out-of-court settlements and litigation, show harm to property, health, safety and welfare of the public. Public health endangered by improper soil analysis ... has led to contaminated wells and groundwater; septic system failures; and compromised wetlands. Harm to the public exists when [action] is approved without a comprehensive soil analysis conducted by a soil expert to support decision[s] taken. Public harm occurs when ordinances excludes a professional group that hold an expertise through education and experience. Exclusion of a qualified group to practice diminishes choice. A significant number of court settlements indicate that there are professionals [who] practice soil science beyond the scope of their expertise. In view of the findings regarding the practice of soil science, the following recommendations [are] made for consideration by the Legislature:

1. That Soil Scientists be regulated; and
2. expertise should be defined to minimize overlap of work to be performed.
   

The sunrise report goes on to indicate that defining what is soil science, and identifying who is a soil scientist is a challenge. Furthermore, without a commercial yellow pages heading for the profession, consumer access to soil scientists is limited to an informal referral system. Professional soil science societies are viewed in the report as ineffective in protecting the public from unprofessional acts by soil scientists or purported soil scientists. Specific examples of damage are provided in the report, including at least $3,000,000 in damage claims due to septic system problems in Cowlitz County in western Washington. Also cited were 20 cases in eastern Washington, provided to DOL by the Washington Department of Ecology, where earlier or more competent soil science consultation could have saved resources and protected human health.

Now that the sunrise report has been submitted, the legislature can move forward during the 2006/2007 legislative session to act on the previous draft. Prospects look good for passage, but regardless of the outcome, Washington soil scientists cannot help but be lifted up by the findings of the sunrise report: Practitioners of soil science are needed in Washington State to a degree that individual practitioners could not have been aware of. While it is extremely disturbing to learn of several instances of unprofessional work by purported soil scientists, it is good to read that quality work is highly valued and recognized as critical to protecting health and resources. Washington soil scientists already know that we are in some demand: once a soil scientist establishes a niche, it is rare to find that individual idle. DOL's survey offers us a unique glimpse into the bigger picture as to why that is.

1997 photo of sprayfield with soil problem.
Olympia Cheese. Lacey, WA.

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Mollisols, Agricultural Systems and the Dangers of Static Thinking

One of my favorite blogs is Muck and Mystery, by Gary Jones, a self described bio-geek. In a December 18th post Muck and Mystery includes a map of the global distribution of Mollisols. The map demonstrates that the best agricultural soils in the world are largely in North America and the European Union. We can expect high crop production from these areas and it is self-evident why nations with productive soils can be expected to demand more fertilizer per unit area. The point Muck and Mystery counters is that patterns of crop production and fertilizer use are largely accounted for by patterns of export subsidies.

Hear, hear. Eliminating farm supports in developed countries will not eliminate long term demand for agricultural exports from the US and EU. While there are compelling elements of truth to the notion that agriculture production is a political toy, it becomes a dangerously simplistic construct when extended to justify redistributing agricultural production on a global scale. The planet has limited areas where soils and climate are ideal for crop production. Ignoring the realities of what the land can, and cannot, support is always a terrible mistake. Doing it in the name of economic justice and environmental protection doesn't make it right.

Ignoring what the land compels in the name of other good causes abounds. Whether it is in the name of endangered species protection, wetland protection, smart growth or prime farmland protection, the supply of ironic disconnects far exceeds demand. Thank you Muck and Mystery for holding our collective do-gooder feet to the fire yet again.

Update:
Here's a link to a news article shedding some light on the complex subject of export subsidies.
Column: Where’s that 18 cents for African cotton producers?
Dec 29, 2005 2:56 PM
African farmers should ask their leaders why their prices are 18 cents below world cotton prices


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Biosolids, Politics and Character

Biosolids, aka domestic wastewater (sewage) treatment solids, is pretty interesting stuff, to me anyway. From a soil scientist's perspective it is chock full of good stuff: Essential plant nutrients and humic substances (humic acid, fulvic acid) beneficial to soil quality. Biosolids is superior to chemical fertilizers from both a crop production perspective and an environmental protection perspective.

This is not raw sewage solids or raw septic tank solids. This is the microbial biomass solids produced during the time the sewage is being treated, usually a 20-30 day process, prior to the treated liquid being discharged to a surface water body. These solids have about the same ratio of N:P:K:S present in soil microbial biomass.

Since the 1972 Clean Water Act, USEPA has been encouraging treatment facilities to give preferential consideration to recycling the soil property enhancing constituents in biosolids. These constituents were originally derived from crops grown on agricultural land and federal legislative intent is to see these materials recycled and put to beneficial use at their source. At the basis of this intent is a conviction that the overall benefits of beneficial use exceeds the added economic and regulatory burden placed upon the local and regional taxpayer and the wastewater treatment ratepayer.

Because of costs to transport material beyond the reach of urban sprawl, it would be cheaper to dispose of it in the ocean, or, for interior cities, in a landfill.

The constituents within biosolids are derived from nonrenewable resources and energy intensive processes and, being a regulated material under the authority of the federal government, cannot responsibly be allowed to be simply discarded when the opportunity for beneficial use is available. This policy makes more sense with each passing year.

Critics and skeptics of beneficial reuse on farm land abound, but fears of environmental degradation have yet to be borne out by events.

Once I had the opportunity in the 1980's to ask the then-President of the Washington State Farm Bureau why the American Farm Bureau Federation had a policy in opposition to land application of biosolids on farmland. He was a respected, retired soil scientist, and I asked for a science-based explanation. Instead, he explained that the national Farm Bureau was using their opposition to biosolids to persuade legislators to address burdensome regulation of farmers related to wetlands and surface water quality. They correctly recognized that Farm Bureau support was valuable and wanted a quid-pro-quo accommodation or to at least be able to make a statement.

You have to respect this point of view. It may not be science-based but its not off base either. That Farm Bureau fellow was just staying in character.

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What is Soil Science?

For those who might think that soil scientists are engineers, a pretty common starting point in understanding, let me explain. Soil science is science - not engineering, not applied technology (which I consider agronomy and crop science to be) and more exactly it is an earth science. Occasionally you encounter puckish-types who place soil science among the life sciences, pointing out that a soil without living processes is simply dead dirt, another construction material for engineers to move around.

To be soil, a natural body must contain living matter. This excludes former soils now buried below the effects of organisms. This is not to say that buried soils may not be characterized by reference to taxonomic classes. It merely means that they are not now members of the collection of natural bodies called soil; they are buried paleosols.

from: Soil Survey Manual - Chapter One: Soil and Soil Survey Modern Concept of Soil USDA Soil Survey Staff, 1993

Some apply technical aspects of soil science within the context of their respective disciplines and call themselves soil scientists on this basis. Declaring oneself as a soil scientist can have an authoritative cachet that comes in handy for getting a little more business and at planning commission hearings. This is troublesome to those of us who have been qualified by our peers as soil scientists.

While the science owes a tremendous debt to agriculturists, engineers and geologists, soil science is not subordinate to any other discipline.

Some confusion about hierarchy is inevitable. It is understandable for folks to see soil science as a branch of whatever they were studying when introduced to the discipline. And it is understandable for non-soil scientist folks with a better understanding of soil science to be mislabeled as soil scientists despite their best efforts. Any real disagreement about standing were eliminated in 1924 when the International Council for Science accepted the International Union of Soil Sciences (IUSS), as a full member , rather than placing soil science within either the IUGS or IUBS.

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