The Soil Science Society of America had its North American Societies Conference (Canada/Mexico/US combined societies) in San Diego this month - https://www.sacmeetings.org/
1,700 people came and gave talks. Lots of talks!!! You can review the topics covered by various categories, such as mineralogy, soil chemistry, microbiology, fire impacts on soil, climate change, soil physics, irrigation management, etc, etc, etc -
or by what was presented each day -
It's a huge amount of information. By clicking on the session, its possible to see the different speakers and topics and see an abstract of the talk. For example, clicking on the Monday, 9:30 AM session on Fire in the Landscape:
- 24 Symposium--Soils of Wildfire-Affected Landscapes: Linking Belowground Ecology & Watershed Processes
reveals a bunch of talks
clicking on the 11 AM talk by Jeff Hatten gives:
24-7 Fire Effects on Soil Organic Matter in a Southern Appalachian Hardwood Forest: Connecting the Movement of Fire-Altered Organic Matter in Soil and Aquatic Systems'. Jeff A. Hatten1, Lauren Matosziuk2, Adrian Gallo1, Katherine Heckman3, Kevin D. Bladon4, Lucas E. Nave5, Brian D. Strahm6, Tyler Weiglein7, Jessie Egan8, Maggie Bowman9 and Ryan Stewart10, (1)Department of Forest Engineering, Resources and Management, Oregon State University, Corvallis, OR, (2)Oregon Sate University, Corvallis, OR, (3)Northern Research Station, USDA Forest Service (FS), Houghton, MI, (4)Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, OR, (5)University of Michigan Biological Station, Pellston, MI, (6)310C Cheatham Hall (0324), Virginia Tech, Blacksburg, VA, (7)310 West Campus Dr., Virginia Tech, Blacksburg, VA, (8)University of Colorodo Boulder, Boulder, CO, (9)INSTAAR, University of Colorado Boulder, Boulder, CO, (10)Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA
And clicking on the title will give the abstract : 24-7 Fire Effects on Soil Organic Matter in a Southern Appalachian Hardwood Forest: Connecting the Movement of Fire-Altered Organic Matter in Soil and Aquatic Systems'.
Fire can have dramatic effects on the quantity and quality of soil organic matter (SOM). While combustion of the O-horizon causes direct losses of SOM, fire also transforms the remaining SOM into a spectrum of thermally altered organic matter. This spectrum ranges from hydrophilic, low molecular weight compounds to highly condensed, hydrophobic carbon (i.e., black carbon and PAHs). These compounds have differing mobility in the environment, and thus their impacts on soils and aquatic systems vary by their mobility. The objectives of this study are to Examine the fate and mobility of 1) particulate and hydrophobic compounds such as black carbon and PAHs and 2) hydrophilic compounds in soil and aquatic dissolved organic matter. Studying the effects of wildfire is always challenging due to the rapid post-fire changes to the environment and lack of robust controls. We overcame those limitations by examining the Chimney Tops 2 Fire which burned 4,617 ha of the Great Smokey Mountain (GRSM) National Park, a National Ecological Observatory Network (NEON) site, in November 2016. We have examined soils from three-time points from an area burned a low-severity (pre-, immediate post-, and 11 months post-fire) and two-time points from areas burned at low to high severity (immediate post-, and 11 months post-fire). These soil profiles have been examined for black carbon and PAH contents. We are currently collecting information on the mobile phases of soil and aquatic organic matter. Here, we will present preliminary data from a study examining the effects of fire on the movement of thermally altered dissolved carbon in soils. All samples have a high concentration of black carbon, and as a result, we could not detect a change in black carbon as a result of a low-severity fire. All profiles showed that the proportion of carbon as black carbon increased with depth to about 10cm and remained constant, suggesting that black carbon is being turned over at a slower rate than other forms of carbon at depth. Samples collected along a severity gradient showed that severity and time-since fire affected the black carbon content. We have evidence that the majority of black carbon missing from the surface soils (i.e., ash bed) has moved into the top 5cm of mineral soil. We expect that the hydrophobic PAHs will follow a similar pattern as black carbon. Overall, we intend for this information to facilitate a thorough examination of the effect of fire on the relative flux of carbon through soil profiles and into aquatic systems.
So, this is how some organic matter moves through the soil after a fire. It doesn't all go up into the air as carbon dioxide, some of it actually migrates deeper into the soil and will probably persist there for a long long time.
Or maybe the whole issue of what constitutes a Healthy Soil interests you? Check out these talks:
Read more about similar and different presentations at the Conference. The full papers based on the abstracts will be out at some later date once they have been properly reviewed for accuracy. That usually takes several months to get all of these presentations organized.
Irrigation and Nutrient Management Field Day
Monday January 14, 2019
555 Las Varas Canyon Road Goleta 7:30 am - 11:30 pm, lunch is provided The event is FREE
but please register -
Learn all about soil moisture sensor systems -
• Using sensors to save water, energy, & fertilizer
• Monitoring & interpreting soil moisture data
• Checking & fixing common system problems
• System configurations & funding opportunities
• Practical and common sense considerations
The Cachuma Resource Conservation District, with funding from the Department of Water Resources, is
pleased to offer this FREE field day event in partnership with:
Low-severity wildland fires and prescribed burns have long been presumed by scientists and resource managers to be harmless to soils, but this may not be the case, new research shows.
According to two new studies by a team from the University of California, Merced (UCM) and the Desert Research Institute (DRI), low-severity burns - in which fire moves quickly and soil temperature does not exceed 250oC (482oF) - cause damage to soil structure and organic matter in ways that are not immediately apparent after a fire.
"When you have a high-severity fire, you burn off the organic matter from the soil and the impact is immediate," said Teamrat Ghezzehei, Ph.D., principal investigator of the two studies and Associate Professor of Environmental Soil Physics at UCM. "In a low-severity fire, the organic matter doesn't burn off, and there is no visible destruction right away. But the burning weakens the soil structure, and unless you come back at a later time and carefully look at the soil, you wouldn't notice the damage."
DRI researcher Markus Berli, Ph.D., Associate Research Professor of Environmental Science, became interested in studying this phenomenon while visiting a burned area near Ely, Nev. in 2009, where he made the unexpected observation that a prescribed, low-severity fire had resulted in soil structure damage in the burned area. He and several colleagues from DRI conducted a follow-up study on another controlled burn in the area, and found that soil structure that appeared to be fine immediately after a fire but deteriorated over the weeks and months that followed. Berli then teamed up with Ghezzehei and a team from UCM that included graduate student Mathew Jian, and Associate Professor Asmeret Asefaw Berhe, Ph.D., to further investigate.
Soil consists of large and small mineral particles (gravel, sand, silt, and clay) which are bound together by organic matter, water and other materials to form aggregates. When soil aggregates are exposed to severe fires, the organic matter burns, altering the physical structure of the soil and increasing the risk of erosion in burned areas. In low-severity burn areas where organic matter doesn't experience significant losses, the team wondered if the soil structure was being degraded by another process, such as by the boiling of water held within soil aggregates?
In a study published in AGU Geophysical Research Letters in May 2018, the UCM-DRI team investigated this question, using soil samples from an unburned forest area in Mariposa County, Calif. and from unburned shrubland in Clark County, Nev. to analyze the impacts of low-severity fires on soil structure. They heated soil aggregates to temperatures that simulated the conditions of a low-severity fire (175oC/347oF) over a 15-minute period, then looked for changes in the soil's internal pore pressure and tensile strength (the force required to pull the aggregate apart).
During the experiment, they observed that pore pressure within the soil aggregates rose to a peak as water boiled and vaporized, then dropped as the bonds in the soil aggregates broke and vapor escaped. Tensile strength measurements showed that the wetter soil aggregates had been weakened more than drier soil samples during this process.
"Our results show that the heat produced by low-severity fires is actually enough to do damage to soil structure, and that the damage is worse if the soils are wet," Berli explained. "This is important information for resource managers because it implies that prescribed burns and other fires that occur during wetter times of year may be more harmful to soils than fires that occur during dry times."Next, the research team wondered what the impact of this structural degradation was on the organic matter that the soil structure normally protects. Soil organic matter consists primarily of microbes and decomposing plant tissue, and contributes to the overall stability and water-holding capacity of soils.
In a second study that was published in Frontiers in Environmental Science in late July, the UCM-DRI research team conducted simulated burn experiments to weaken the structure of the soil aggregates, and tested the soils for changes in quality and quantity of several types of organic matter over a 70-day period.
They found that heating of soils led to the release of organic carbon into the atmosphere as CO2 during the weeks and months after the fire, and again found that the highest levels of degradation occurred in soils that were moist. This loss of organic carbon is important for several reasons, Ghezzehei explained.
"The loss of organic matter from soil to the atmosphere directly contributes to climate change, because that carbon is released as CO2," Ghezzehei said. "Organic matter that is lost due to fires is also the most important reserve of nutrients for soil micro-organisms, and it is the glue that holds soil aggregates together. Once you lose the structure, there are a lot of other things that happen. For example, infiltration becomes slower, you get more runoff, you have erosion."
Although the research team's findings showed several detrimental effects of fire on soils, low-severity wildfires and prescribed burns are known to benefit ecosystems in other ways -- recycling nutrients back into the soil and getting rid of overgrown vegetation, for example. It is not yet clear whether the negative impacts on soil associated with these low-severity fires outweigh the positives, Berli says, but the team hopes that their research results will help to inform land managers as they manage wildfires and plan prescribed burns.
"There is very little fuel in arid and semi-arid areas, and thus fires tend to be short lived and relatively low in peak temperature," Ghezzehei said. "In contrast to the hot fires and that burn for days and weeks that we see in the news, these seem to be benign and we usually treat them as such. Our work shows that low-severity fires are not as harmless as they may appear."
The study, "Soil Structural Degradation During Low?Severity Burns," was published on May 31, 2018 in the journal AGU Geophysical Research Letters and is available here: https:/
The study, "Vulnerability of Physically Protected Soil Organic Carbon to Loss Under Low Severity Fires," was published July 19, 2018 in the journal Frontiers in Environmental Science, and is available here: https:/
The Ventura County Resource Conservation District (VCRCD) was awarded approximately $152,000 in grant funding through the State Water Resources Control Board to purchase materials for erosion control purposes on fire-impacted lands within Ventura County. Landowners impacted by the Thomas Fire are able to apply for the materials they need to help mitigate fire-based erosion on their properties. Materials include, but are not limited to:
- Silt fencing
- Jute netting
- Filtrexx Siltsoxx
- Livestock fencing
- Native plants
- Straw wattles
- Alternative water supplies (livestock)
The last day to apply for erosion control materials is March 19, 2018. For more information, or to apply for the program, click here.
Here is a really good introduction to the use of the on-line Soil Survey from USDA. Maybe it is easier to follow than blogs I have posted in the past.
WASHINGTON — “Soil don't get no respect,” Rodney Dangerfield might have said (but didn't). Perhaps you know your state bird or flower, but do you know your state soil?
Well, in recent years soil has begun to get more respect. Since the celebration of the Soil Survey Centennial back in 1999, each state has been given its own official state soil. It was in 1899 that the U. S. Department of Agriculture started its survey of all the soils in the country.
SOILS COME IN MANY ‘Flavours'
You might wonder what a “soil survey” really is. Isn't it all just dirt — some perhaps stickier, or redder or deeper — that lies beneath forest, meadow, farm, home and garden?
There you go again. Not enough respect.
In fact, soils are distinctive, as different from each other as robins are from blue jays. These differences are hard to appreciate, of course, because soil is mostly underground, hidden from view. But if you were to dig some holes a few feet deep and then look carefully at their inside surfaces, you would find that soils are made up of layers of varying thickness, called horizons. One soil might differ from the next not only in the thickness of its horizons, but also in their appearance and feel.
Horizons might be as white as chalk, as red as rust, or as dark brown as chocolate. A horizon might be cement-hard, gritty with sand, or stuff for sculpture. And if you were to tease the dirt along one edge of the hole so it falls away naturally — wow! — each horizon would reveal its particles clumped together in arrangements like plates, blocks or prisms. Such information, and more, has allowed soils to be classified, much as birds, flowers and other living things are.
Modern soil classification goes back only a few decades, when all the world's soils were grouped taxonomically into a dozen “orders.” Differences among orders reflect the formative influence of a particular combination of climate, plants and animals, topography, time and original rock material.
Just as all vertebrate animals are huddled together by biologists into smaller groupings (mammals, say) and those groupings into still smaller ones, so each soil order is divided and subdivided to include more distinctly different soils. At the end of the dividing and subdividing, you end up with a “soil series” identified with a proper name — like the Haven series in my vegetable garden, for example.
YOUR STATE'S AND BACKYARD'S SOIL
A particular soil becomes an official state soil by being widespread within the state; being distinctive chemically or physically; having some degree of name recognition; and, of course, getting a legislative stamp of approval. Examples include soils like West Virginia's Monongahela soil, Texas' Houston Black soil, California's San Joaquin soil and New York's Honeoye soil.
The job, now, of these “ambassadors” of the benevolent underworld is to rekindle awareness of soil's value as a natural resource that can only be renewed very slowly. Soil provides food, shelter, clothing and more, yet it is being lost at alarming rates to everything from blacktop to erosion.
Out in the garden this spring, dig a hole deep and wide enough that you can see and appreciate at least some of the various and distinctive horizons.
Then, if you want the name and a detailed description of that soil — or any soil — look at the maps and descriptions in the Soil Survey Reports issued by the U. S. Department of Agriculture, Natural Resource Conservation Service (NRCS). Search online for “soil survey nrcs” and you'll find links to soil maps for counties throughout the U.S. Or go to the link to “web soil survey.” At this site, you can type in a street address around which you “draw” your area of interest (AOI). The site will delineate the names and descriptions of soils within that AOI.
And of course this is available as an app at: