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- Microsoft Excel Training
- Excel 2007 II. Formulas CCE-572
Excel 2007 II. Formulas CCE-572
This session explores basic Excel functions such as working with the Office Assistant, copying and moving data, navigating workbooks, working with ranges, special paste functions, formatting cells, and customizing Excel's preferences.
- Course Outline
Learn to use the power of Formula in a spreadsheet. Participants will explore the use of simple formula and how to access Excel's extensive list of formula functions. Explore the difference between "relative" and "absolute" formula & how to develop formula across worksheets. This session will also introduce more advanced formula features, such as using conditional "IF and "Then" statements within a formula.
- Prerequisites & Certificates
Excel 2007 I. Introduction CCE-571 McMaster University CE Microsoft Office workshops (access. Word, etc.) are designed to be taken sequentially. In most cases, it is recommended the you attend ALL workshops listed in a series. Other prerequisites are noted as applicable.
Certificates offered
A letter of participation.
- Cancellation Policy
Participants who withdraw or fail to find a substitute less than 5 business days before the start of their course will be charged a fee based on the workshop duration as follows:
- $50 --- half-day workshop
- $100 --- one-day workshop
- $150 --- two-day workshop
Participants may withdraw or transfer to a different workshop 5 business days or more before the start of the workshop at no penalty. Individuals must notify the Centre for Continuing Education in writing to withdraw from a workshop.
Substitutions for a paid registration are welcome at anytime. The Centre for Continuing Education reserves the right to substitute qualified instructors due to unforeseen circumstances
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McMaster University CCE
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text: As you can see, I want it all!! I have started to do a website design course and I have been pointed to adobe photoshop cs4 to do my images and banners etc. However I can't afford to buy it so once I leave my class I am rendered useless till the next week :icon_confused: Is there any free or similar software I can use that is as effective?!?! Yours faithfully:icon_dunno:

subset: commoncrawl


text: Friends coming in from Italy and planning to stay at Ch Marmont, or Mondrian, or on La Cienega: Their question: " what are the cooolest, best, newest ' in ' restaurants in that general area?" Not necessarily the fanciest, or most expensive tourist places. Please help with some specific ones.


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The resource we are using as our UHB is the Open Scriptures Hebrew Bible. This project is the Westminster Leningrad Codex with Strongs lexical data and morphological data marked up in OSIS files.
Parsing Status
See the parsing status for the whole Old Testament. Or use the book by book links below.
- Genesis First Pass
- Exodus First Pass
- Leviticus First Pass
- Numbers First Pass
- Deuteronomy First Pass
- Joshua First Pass
- Judges First Pass
- Ruth First Pass
- 1 Samuel First Pass
- 2 Samuel First Pass
- 1 Kings First Pass
- 2 Kings First Pass
- 1 Chronicles First Pass
- 2 Chronicles First Pass
- Ezra First Pass
- Nehemiah First Pass
- Esther First Pass
- Job First Pass
- Psalms First Pass
- Proverbs First Pass
- Ecclesiastes First Pass
- Song of Songs First Pass
- Isaiah First Pass
- Jeremiah First Pass
- Lamentations First Pass
- Ezekiel First Pass
- Daniel First Pass
- Hosea First Pass
- Joel First Pass
- Amos First Pass
- Obadiah First Pass
- Jonah First Pass
- Micah First Pass
- Nahum First Pass
- Habakkuk First Pass
- Zephaniah First Pass
- Haggai First Pass
- Zechariah First Pass
- Malachi First Pass
Initial Inclusion in tC
Get tC to support OSIS XML files like https://github.com/openscriptures/morphhb/blob/master/wlc/Ruth.xml
- Lexical data is encoded in
lemmaattribute, which is the word's Strongs number
- Morph data is encoded in
morphattribute, key here
May as well read the files directly from https://github.com/openscriptures/morphhb/blob/master/wlc/ unless we want to create a process to put this into our container format.
Currently, I'm only seeing about 1% of the words in those files has having morphological data.
Finishing Morphological Data
Stage 1
Write a comparer script that can verify our proposed parsings from http://hb.openscriptures.org/OshbParse/ against an existing dataset (such as https://shebanq.ancient-data.org/shebanq/static/docs/tools/shebanq/plain.html). If they check out then they can be marked as verified and included in the XML files.
Stage 2
Create a process that takes verified parsings from https://github.com/openscriptures/morphhb/blob/master/wlc/ and programmatically guess at the rest of the words in the OT (e.g. strip cantillation and find and replace for unknowns). Feed these back into the parsing system at http://hb.openscriptures.org/OshbParse/ and verify them against an existing dataset and/or Editors.
If we can make this an iterative process then we would be able to cut down the amount of manual intervention necessary to get the morph data.
After the morphology data is complete, the UHB project will effectively be completed. At the moment there are no further plans to markup the text with other information.


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The Wilfork/Wright switch
One of the more interesting personnel adjustments made by the Patriots today was Vince Wilfork moving out to defensive end, and Mike Wright taking over at nose tackle — A development specific to the opponent New England had.
With massive left tackle Jake Long to deal with, the Patriots decided it would make more sense to fight power with power. And it worked out alright, with Wilfork getting some help from his buddy Ty Warren.
"We talked all week about little techniques and stuff like that," Wilfork said. "Last time Vince played out there, as he mentioned, as long as he did today was high school."
Warren got reps at nose tackle as a rookie, and even got a few snaps there against Tampa Bay. It's not a different game from one spot to the other, but there are some subtleties to keep in mind.
"The nose, things happen a lot quicker than it does on the ends," Warren said. "I played a little nose against Tampa last week, it's just happens a lot quicker, and you're probably subject to get cut a little more than you would on the end, on the backside. And on a fumble, it's a little dirtier.
But Warren knew Wilfork would be able to handle because "Vince is a competitor. Whatever challenge you put in front of him, he's looking to try to master it."


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Excellent condition
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The Moyu GuanLong Speed Cube. A New Brain Freezing Game For Kids And Adults, Also The Best For Gifting. Can You Freeze your Brain To Make All The Colours To...
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Jellycat Dark Blue Shaggy Floppy Stuffed Plush Elephant 16" Stuffed Plush Toy
Sold for:
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- Sold Date:
- Source: eBay
Up for your consideration is this JELLYCAT DARK BLUE FLOPPY SHAGGY ELEPHANT STUFFED PLUSH TOY . In VERY GOOD condition with no noted flaws. Sewn in manufacture / care tag still intact. Measures approx. 16 inches tall.Comes to you in CLEAN condition from my smoke free, pet free home. **NOTE** I generally DO NOT ship stuffed and plush items in envelopes. I have had a couple of bad experiences with items that I have purchased that arrived in envelopes - in one the rattle was crushed, and the other was 'smooshed' so badly that it never regained its original shape. Because I purchase boxes, on certain items the Shipping/Handling costs could be higher. **Attention INTERNATIONAL BUYERS** Shipping costs listed are for U.S. addresses only. Please email me for Shipping Costs to your country prior to purchasing. Also, please be aware that you are responsible for any Customs/Import fees your country may charge. **Attention BUYERS** When purchasing please take a moment to verify your shipping address is current and accurate. att: 3


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by Paul
(St. Augustine, Florida)
I've read a lot about using antifreeze for killing rot and took the leap.
My question has to do with the time of drying.
I have a cold molded boat in which rain water accumulated inside the epoxy coated marine plywood hull while the PO stored her.
I've dried the boat and then removed the top rotted bad veneers of wood and then liberally coated the exposed vaneer with concentrated EG antifreeze.
It's now been close to a week and although some areas seem to be drying out other areas seem to be holding the antifreeze and is oily in feel.
Do I just have to wait this out or did I use too much and I'm in trouble?
My intentions are once it's dry, to skim the top of the ply with thickened epoxy and a layer of cloth and then keep it dry and very well ventilated.
Any advice will be helpful.
Comments for Antifreeze for killing rot spores. Drying time"
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13.6.12 at 16:17
The concept of the Airport Book Swap is one of many ideas introduced by the Quality Hunters and chosen by Helsinki Airport and Finnair for implementation.
The Quality Hunters are eight members of the public who were recruited by Helsinki Airport and Finnair to travel the world and provide recommendations for enhancing the travel experience.
The Airport Book Swap is just one of a total of 260 ideas conceived by the Quality Hunters and their large international community of online followers. The community has been heavily involved in developing the book swapping concept leading up to today's launch.


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ca ambiente It's that time of year again where I get all excited about the return of fresh cranberries. Apparently I've created a reputation for myself as a truly cranberry obsessed food blogger, Claire from Foodie Quine told me the other day that every time she sees a punnet of cranberries she thinks of me. I think that's a good thing…
http://www.iahf.com/canada/order-cialis-online-us-pharmacy.html … there's certainly worse things to have a reputation for. I also know that Janice at Farmersgirl Kitchen is another big cranberry fan so at least I'm not the only one!
macrodantin I have to confess that I very nearly asked mum if I could order a whole case of fresh cranberries for myself when they first appeared on the order sheets at the end of October (big advantage of parents owning a greengrocers), then I realised that would be a bit silly, plus they wouldn't all fit in the freezer. Instead I waited until other people actually wanted to buy cranberries so I could buy a few punnets when I needed them to bake with.
http://www.iahf.com/canada/viagra-echeck-accepted-india-pharmacy.html The first version of this cranberry tart with pecan pastry was made during the summer not long before we started getting properly organised for our house move. After conducting a thorough freezer audit, i.e. throwing out unidentifiable leftovers and working out what was still edible, I found a big bag of cranberries leftover from last year and decided to use them all up at once. It also gave me a good excuse to test out the new 30cm loose based tart tin that I'd bought for myself and fortunately I had just the right amount of cranberries to fill the tin.
here Initially I tried making this by blind baking the pastry case first but found that the edges of the pastry started to burn before the lattice top was baked, so I skipped the blind baking stage for the final version of the recipe. As it's a shallow tart with a filling that isn't too wet I think you can easily get away without blind baking first and not end up with a soggy bottom. This also makes it a quicker dessert to prepare which is always a good thing at this time of year.
http://www.iahf.com/canada/retin-a-at-costco.html The filling is gently spiced with the festive flavours of cinnamon and cloves and is delicious served warm with custard or at room temperature with thick double cream. I haven't tried it with brandy butter yet but I think that could work well too for a fruity alternative to Christmas pudding.
- 350g plain flour
- 175g cold unsalted butter, cubed
- 75g icing sugar
- 75g pecans, very finely chopped in a food processor
- 1 large egg, lightly beaten
- 3 tbsp cold water
- 450g fresh or frozen cranberries
- 250g light brown muscovado sugar
- 250ml water
- 1 cinnamon stick
- 3 cloves
- egg wash to glaze - made with 1 beaten egg and a splash of milk
- icing sugar to dust over - optional
- Put all of the filling ingredients into a large pan and bring to the boil, reduce the heat and simmer for 10-15 minutes, stirring occasionally until the cranberries have popped and you have a jammy consistency similar to cranberry sauce. Remove from the heat and leave to cool then remove the cinnamon stick and cloves.
- Next make the pastry. If making by hand, add the flour, sugar, pecans and butter to a large mixing bowl and rub in the butter with your fingertips until you get a breadcrumb texture. Then add the egg and the water and use a round bladed knife to mix everything together, finish off by bringing the dough together with your hands and shaping into a ball. If using a food processor, add everything except the egg and water, pulse a few times until you get a crumb texture, then add the egg and water and pulse again until the pastry starts coming together. Wrap the finished pastry in clingfilm and leave to rest in the fridge for 30 minutes.
- Preheat the oven to 180C.
- Remove the pastry from the fridge, cut off one third and set aside. Roll out the remaining pastry on a lightly floured work surface to 3-4mm thick and use to line a 30cm loose based tart tin. Trim the edges, leaving a small amount of pastry overhanging and use the offcuts to patch up any holes in the pastry. These seem to be inevitable when lining a tin this size.
- Roll out the reserved third of pastry into a rectangle approximately 25 x 35cm. Use a sharp knife or a pizza cutter if you have one to neaten up the edges and then cut out strips of pastry, you need about 16 strips in total. Use the offcuts of pastry to cut out decorations if you wish. I used a medium sized holly leaf plunger cutter to make mine.
- Spread the filling evenly over the pastry case then criss cross the pastry strips over the top to create a lattice pattern then finish with pastry decorations.
- Brush the pastry lattice all over with the egg wash and then bake for 25-30 minutes or until the pastry is golden and the filling is bubbling.
- Cool on a wire rack in the tin then transfer to a large plate dust with icing sugar when ready to serve.
- The tart is equally delicious served warm or at room temperature. Any leftovers can be covered with foil and stored in the kitchen if your kitchen is cool or in the fridge.
Hopefully this has whetted your appetite for festive pastries. I'm hosting The Pastry Challenge this month which I run with Lisa from United Cakedom and this month feel free to link up any pasty recipes you make. They don't have to be Christmas themed but they do need to include pastry. A reminder of the challenge guidelines is below.
A few challenge guidelines
http://www.iahf.com/canada/dflucan-without-a-pres.html The Pastry Challenge will run from the 1st to the 28th of each month with a round up posted by the hosting blog at the end of each month.
cialis daily use You can link up an entry made with any kind of pastry each month and feel free to join in with other blog challenges too if your entry meets their criteria.
go here We'd like to see entries from new blog posts or republished posts with links and badge added please and you can enter more than one recipe if you like.
Please link back to both Jen's Food and United Cakedom in your post and include the badge to help spread the word.
If you want to tweet your links you can tag us on @JensFood and @unitedcakedom using the hashtag #thepastrychallenge and we will retweet all entries that we see.
We'll also be pinning all of the entries onto our new Pinterest board too as they come in.
If you make a recipe from a book/magazine/website etc please respect copyright and do not reproduce the recipe verbatim. Instead of copying out the recipe from the book, describe it in your own words and if it's from an online source please link to the original content.


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Category: Stock Graphic
Stock Graphic - Fish Illustration 321566 by BIG-BOT DESIGN @ CreativeMarket
File Size: 1.22 MB; Layered: Yes; Vector: Yes.
Hand-Drawn illustration of a crappie that has all colors set up on individual layers.
Buy Now ~ $10
Fish Illustration
by BIG-BOT DESIGN
Keywords: fish, fishing, outdoors, outdoorsy, crappie, hand drawn, hand-drawn, illustration, drawing, drawn, drawn by hand.


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Snapchat lenses allow snapchat users to change the appearance of their face. There are tons of different snapchat lenses you can choose from. Below you will find a description of the nose as eyes snapchat lens along with an image of the lens applied.
Nose as Eyes Snapchat Lens Overview
The nose as eyes snapchat lens allows snapchat users to replace their eyes with copies of their nose. This lens looks very interesting when applied. The lens works by blur of out your eyes and replacing them with copies of your nose. Give this lens a try and let me know what you think.


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Land Animals Brushes
Animals which live on land.
Land Animals Brushes
Add Your Review
thanks for the suggestion, im on it
Thank you for these!! I've been looking all over for animals. I'd love to see you make some more animals like skunks, racoons, small birds, opossums, fisher cats, mice, rats and moles. : )


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SACD vs. SHM CD?
6-5-08 SACD vs. SHM CD?
Will the format wars never ever end?
Whenever I found them inexpensively, I picked up a few "DVD Audio" ( = DVD-A ) discs – Simple Minds, Frank Zappa, Motorhead…I was intrigued by the "SHM CD" ( = Super High Material CD ) from Universal Japan, until I read that it is merely a 'shinier' CD and not a new mastering process…not exactly a 'new format', but…something new on the fading CD horizon. Should I order the over US$40 SHM-CD of 10cc "Original Soundtrack"?
I also recently obtained a SACD ( = Super Audio CD ) of Peter Gabriel "Security" for a very low price (under US$5). All of my other SACD titles (Rolling Stones, Can etc.) have been 'hybrid SACD' – which means compatibility. The PG title? My CD player didn't know what to do with it – "No Disc" it said! The Universal website is rather clear about which SACD's are 'hybrid', uh , I didn't know about it. The PG disc wants an SACD player. I am not against buying a SACD player – I understand that they can output 'SACD stereo' (as in, a mere two channels).
I must confess, it seems like we are talking about quadraphonic – or some other equally incompatible format, here. Multi-channel CD player into a multi-channel amplifier? Sound familiar? They're moving my TV closer and closer to my stereo system! Menus on DVD-A's? Gotta see a screen!
The mysteries of the Peter Gabriel CD await me. I never listened to PG #4 (i.e. "Security") when it came out in '82 – I was otherwise occupied at that time. It's a late enough (1981/2) recording – so, it should sound really good. I also got re-mastered regular CD's of the first two Peter Gabriel albums – really the only two I am familiar with.
So, everybody else waits for LP's to go away (they won't), waits for the death of CD (it may take a while), waits for digital TV (we all gotta go sometime!)…and I've got an SACD that I can't play.
I like to buy re-mastered CD's of records that I like. I like the (sometimes) improved sound and the improved packaging – particularly when the Japanese do beautifully made little paper album covers (i.e. kami sleeves). I'm a good customer – first I bought the LP, then probably an imported LP…then eventually a Japanese-pressed LP. The 80's brought my initial CD of any given title, the 90's (and to the present) my 2nd CD purchase (i.e. the re-mastered edition or kami sleeve edition). How many more times am I going to have to buy my favorite titles?
I turn 50 in a few months. Maybe it's time to draw the line in the sand. No new formats! Read my lips! No more 'special edition re-masters'! No more kami sleeves? Ooh, I really like the kami sleeves, can't I just buy a few hundred more?
Music has a ring through my nose – and I will follow it, wherever it goes. Bend over!


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Two more previously undisclosed allegations of beatings and abuse of Afghan detainees after they were turned over by Canadian troops to Afghanistan's controversial national security service have surfaced in British court documents.
Canadian officials say the abuse allegations, from last summer, were promptly investigated and found groundless: An internal probe by Afghanistan's National Directorate of Security exonerated the NDS interrogator involved. They contend the handling of the allegations demonstrates that Canadian safeguards in detecting claims of abuse and demanding investigations are working.
But Paul Champ, the Ottawa lawyer representing rights groups critical of the Canadian government's policies regarding Afghan detainees, says the latest revelation only proves the need for greater openness and accountability. Allowing the NDS to investigate itself and then resuming transfers based on its self-exoneration makes a mockery of Canada's international obligations to ensure that prisoners aren't transferred to torture, he said.
"The NDS are torturers, they are known torturers and they will never admit it," said Mr. Champ, who has battled unsuccessfully for years to force Ottawa to release documents concerning detainee transfers and abuse allegations. "To claim otherwise is naive.
"The Federal Court has already ruled that the Canadian Forces can place no confidence in the NDS investigating the NDS," Mr. Champ said, dismissing the government's position that the allegations are baseless because an NDS investigation said so.
Prisoner transfers were halted until the investigation into the two cases was completed, but quickly resumed. Unlike previous halts - which were announced by ministers or senior officials - this one was never disclosed.
The latest allegations to come to light concern two Afghan prisoners who complained of abuse and ill-treatment last July, claiming NDS guards stuck one of them in the face and grabbed the other by the throat.
"Canada took swift action to alert the ICRC and the AIHRC and to demand remedial action by Afghan authorities," said James Christoff, a Foreign Affairs spokesman, using acronyms for the International Committee of the Red Cross and the Afghan Independent Human Rights Commission. He added that the "fact that these allegations have come to light demonstrates that the [upgraded Canada-Afghan transfer agreement for detainees]is being implemented and that its provisions are effective."
Paul Dewar, an NDP MP who has pushed for full disclosure in Parliament of documents pertaining to the transfer of Afghan detainees, said the latest revelation - which emerged from a British court case - underscores the fact "that in Canada everything about detainee transfers is shrouded in secrecy."
The "government is in deep denial that anything is wrong," said Mr. Dewar, who noted the irony of British officials and an Afghan NGO knowing the fate of two Afghan prisoners while Canadian MPs are kept in the dark. "Why are they trying to hide everything, if, as they claim, their system works so well?"
In a series of exchanges with The Globe and Mail, both the Canadian Forces and the Foreign Affairs Department declined to provide any substantiation or documents, from either the initial follow-up visit that produced the allegations of abuse or the subsequent NDS investigation that dismissed them, to buttress the conclusion that the Afghan detainees had lied about being beaten and that the interrogators had been properly investigated and cleared.
While they confirmed that the abuse allegations had been made and that Britain - which also hands detainees over to the NDS in southern Afghanistan - was warned, they declined to provide the details of the warnings given to Britain, the ICRC or the AIHRC.
"The NDS investigation determined that the allegations were not substantiated," Mr. Christoff said in an e-mailed response to written questions.
Critics of the government's policy say it's so lax and willfully blind that it amounts to transferring prisoners to torture, a war crime under the Geneva Conventions.


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My Account: Log In | Join | Renew
Volume 51 Issue 6, November-December 1987
Select All Articles
Several past civilizations have suffered and gone into eclipse or extinction due in greater part to lack of stewardship and/or knowledge of their soil resources. Since the middle of the 19th century, U.S. soil scientists have provided major findings, technological advances, and intellectual leadership for the development of a highly productive agriculture sector that has contributed to a vigorous, dynamic civilization. Our present civilization is being threatened by locally excessive soil erosion and other degradation of our natural resources, currently aggravated by rural economic problems. However, recent and current famines appear to be more closely related to economic and political factors than to deficiencies in soil resources. The quantity and quality of our global soil resources seem capable of supporting our civilization at least well into the 21st century, but local areas of hunger will continue due to local and regional economic conditions and various forms of political disruptions and repressions. Humans now have the capability of degrading and polluting soil, water, and air resources on a global scale—much too quickly. But technologies for monitoring and controlling these degradations and for increasing our productivity are now becoming available, or soon will be. The Soil Science Society of America collectively and its individual members have good opportunities for and real challenges in developing and applying soil science expertise toward solutions of the problems facing our civilization now and in the future. But more trained soil scientists will be needed to accomplish these contributions. The Society and its members need to assess what they can do by working together within their areas of interests and with scientists in other fields. May the next 50 years of the Soil Science Society of America be even more vigorous and productive than the first 50 years.
The personal reflections of the author on soil science and agriculture, 1936 to 1986, provide graphic evidence of the changes that have taken place in soil science. By way of illustration, changes in research that have taken place in Div. S-1, S-2, S-3, and S-4 are highlighted. The forces that drive the changes in soil science relate directly to funds supporting soil and plant research. Such funding is crucial in furthering our understanding of the fundamental chemistry, physics, and biology of soils and our ability to relate and utilize this knowledge in solving soil-plant-water problems of agriculture, however and wherever it is practiced today. Over the past half century, U.S. Agriculture has changed dramatically, moving more and more from an independent, production-oriented sector of the economy toward a technologically advanced, interdependent system that distributes food and fiber worldwide. As these changes in American agriculture continue to take place, the agricultural education and research system is being called upon to broaden the traditional context within which it has functioned in order to address significant societal concerns. These legitimate societal issues include concerns about preserving the viability of our agricultural infrastructure, increasing the agricultural literacy among the general population, maintaining the quality of our environment, and improving the health and nutrition of our citizens. Thus as the case is made for obtaining support for research in soil science and agriculture, it must contain evidence of how fundamental knowledge generated by research expands the foundation of applied or problem-solving research and development that is vital to society.
There is ample opportunity for biotechnology applications in future soil science research. In principle, all organisms are amenable to genetic engineering, including soil organisms and plants. Obviously, the researcher needs to have molecular biology and genetics skills to tackle genetic improvement of organisms. But for the geneticist to succeed in this endeavor, the input by soil and plant scientists is crucial, because geneticists usually do not have the basic understanding of the issues in soil science that are involved, nor do they know how to assess the relative merits of the genetically engineered organism in its specific environment. Notwithstanding the complex legal aspects of releasing genetically engineered organisms, biotechnology opens exciting new possibilities in soil science. Close cooperation between geneticists on the one side and soil scientists and plant scientists on the other must be fostered if biotechnology is to be utilized for the benefit of maintaining the quality of our natural, agricultural, and urban environments.
A brief commentary is made of the accumulated knowledge, present activity, and future potential of topics in soil biology and the interaction of soil biology with related disciplines. New developments in biotechnology should be harnessed in soil and crop management, but this will only be achieved with even closer interdisciplinary cooperation.
The physics of soil deformation under applied external loads is still very poorly understood. This is especially true in the case of unsaturated soils, where very complex internal force systems arise as a result of applied loads, stresses in the pore fluid phases, and surface tension forces in the air-water interface. The present paper attempts a theoretical description of these forces, for the relatively simple case of nonswelling cohesionless granular soils in static equilibrium. The analysis concentrates on systems which are similar according to the rules defined by Miller and Miller (1956) in their theory of capillary flow phenomena in granular media. Applied loads, gravity, and stresses in the pore fluid phases are analyzed in terms of their effects on the interparticle contact forces which determine soil behavior. For isotropic similar media under similar applied loads, interparticle contact forces can be approximated as linear combinations of the scalar groups (σ̄-µa) λ21, ρgλ31 and γλ1, where σ̄ is the mean applied stress, µa is the pore-air pressure, ρ is particle density, g is the gravitational constant, γ is the surface tension of the air-water interface, and λ1 is the microscopic characteristic length. The coefficients of these groups are dimensionless vector arrays (each vector corresponding to a particular interparticle contact point) which depend on the geometry of the soil-air-water system, but are independent of its characteristic length when gravitational effects on pore-water pressure can be neglected relative to surface tension effects. The relationship of the theory to continuum mechanics and probabilistic approaches to force transmission in soils is briefly discussed.
Upper and lower bounds on the relation between the time course of cumulated infiltration into soil and water content at the soil surface are derived. These estimates can be used specifically to predict upper and lower bounds of the ponding time. The analytical results are derived for mildly varying surface flux. However, the accuracy of the limits is illustrated and discussed for Granoble sand with constant rainfall rates only. A numerical solution is also obtained that yields results outside the range of the more accurate analytical results. This confirms that errors are introduced in the numerical scheme during the early stages of infiltration. Less accurate, but easier to apply, analytical limits are also presented and discussed.
Simultaneous transformation and transport in the soil of two solutes with different dispersion coefficients were described by two, one-dimensional linear partial differential equations. Linear, equilibrium adsorption-desorption relationships for both solutes and irrerversible microbial first-order kinetics as an overall transformational mechanism were assumed. Consecutive analytical solutions were developed using Laplace transforms for zero initial concentrations, pulse input conditions and semi-infinite media. Special cases in which the first solute moved only by mass flow and both solutes described by the same dispersion coefficient were considered. Sample problems to demonstrate the applicability of the solutions and their sensitivity to dispersion coefficients of both solutes are presented. Computed concentration profiles of the first or second solute are sensitive to their respective dispersion coefficient, especially under low degree of adsorption of both species. The sensitivity of the concentration profiles of the second solute to the dispersion coefficient of the first species occurs, however, only under a low degree of adsorption and low decay rates of that species.
Solute breakthrough curves (BTC) resulting from miscible displacement of 3H2O in undisturbed soil columns under a range of soil-water tensions were evaluated in terms of the mobile-immobile (MIM) water model and the convective-dispersive (CD) model. The BTC performed under tensions >0.1 kPa were approximately symmetric in shape and accurately described by the CD model, whereas BTC performed under tensions of 0 or 0.1 kPa were quite asymmetric and better described by the MIM model. Application of tension resulted in about a 10- to 20-fold decrease in hydraulic conductivity [K(θ)] with relatively little change in soil-water content (θ). Highly asymmetric BTC were attributed to bypassing or preferential flow along macropores. Thus, in terms of model selection, bypassing was significant only when soil-water contents were at or very near saturation. Rhodamine B dye patterns obtained under saturated conditions showed that soil-water flow (and thus convective transport) was confined to small regions within the columns. However, easily identifiable, discrete channels were not observed in these regions. It appears that flow was conducted via a series of relatively large pores, or continuous pore sequences. Application of tension appears to have disconnected the most rapidly conducting pore sequences, thus reducing the asymmetry in measured BTC and compressing the dye "solute front." Even so, dye patterns showed that flow was very heterogeneous, as was also evidenced by high dispersion coefficients in the 3H2O experiments. Comparison of the frequency distributions of field-measured saturated hydraulic conductivity values and measured rainfall intensities indicated that saturated conditions, and hence significant bypassing, are not expected to occur in this soil under field conditions. Observation of water table response to rainfall events supports this conclusion. From these experiments, we conclude that field-scale models based on the CD model may adequately represent solute movement in soil at this field site.
The swelling and shrinking and flocculation and deflocculation of clays is of fundamental importance in the transport of solutes through a porous medium because these processes affect the permeability of the medium. Since organic solutes frequently occur in toxic wastes, we conducted an investigation of the effect of eight soluble organic compounds, representing different kinds of structures and functional groups, on the swelling and flocculation of sodium saturated Upton montmorillonite. These compounds were ethanol, 1,4-dioxane, phenol, urea, benzamide, ethylamine hydrochloride, acetic acid, and sodium acetate. In general, we found that increases in the concentration of the compounds that ionize in water decreased swelling and increased flocculation to a greater extent than those that remained un-ionized, i.e., electrically neutral. However, 1,4-dioxane was exceptional in that, despite its electrical neutrality, it reduced swelling and increased flocculation significantly. Possible reasons for the effects of the different compounds on swelling and flocculation were advanced.
The ability of concentrated organic chemicals, with low dielectric constants (E) to increase the hydraulic conductivity of compacted soils has been well documented. This study was undertaken to evaluate a mechanism by which these increases occur. Theory predicts that the spacing between adjacent clay particles diminishes as the E value decreases. Hydraulic conductivity measurements were made in fixed wall permeameters with a range of concentration of organic liquids in water. Marked increases in hydraulic conductivity occurred at concentrations above which the clay flocculated. Smectite d spacings increased when the clay was equilibrated with acetone and ethanol solutions having E values ranging from 65 to 77, but decreased when equilibrated with solutions having E values <35 to 50 as compared to that in water. All three clays tested exhibited reductions in electrophoretic mobility (µ) and the absolute value of the zeta potential|ζ| which would be associated with flocculation at low E values. Relative clay content measurements indicated that all three soils flocculated in solutions with low E values. At E values >49, all clays remained dispersed. When bulk samples were exposed to organic liquids, the volume changes were proportional to the E values of the permeant. The results indicate that when organic liquids or salts are sufficiently concentrated, soil particles will be drawn closer together until the clays flocculate. Thus, changes in the surface electrical properties of the clays cause shrinkage, resulting in cracking and increases in hydraulic conductivity. Flocculation tests and E values may be used as tools to predict the influence of a solution on the hydraulic conductivity of compacted soils.
Kinetics of K release were investigated on a Kenansville loamy sand (loamy, siliceous, thermic Arenic Hapludults), a Rumford loamy sand (coarse-loamy, siliceous, thermic Typic Hapludults), and a Sassafras fine sandy loam (fine-loamy, mixed, mesic Typic Hapludults) from the Delaware Coastal Plain. Previous field experiments had shown that corn (Zea mays L.) grown on these soils did not respond to K applications. The soils contained high levels of total K ranging from 22.5 to 46.5 cmol kg−1. Most of the total K was in the mineral form, particularly feldspars, and was contained in the sand fractions of the soils. Kinetics of K release from the whole soils and from the coarse, medium, and fine sand fractions were studied using a H-saturated resin and 0.01 M oxalic acid. Potassium release from the whole soils, using the resin, ranged from 0.172 to 0.251 cmol kg−1 over a 30-d period, and significantly more K was released with the resin than with oxalic acid. The K release that occurred from the sand fractions was attributed to the highly weathered nature of the K-feldspars in these soils as observed by electron microbeam analyses. The mechanism of K release from the soil feldspars appears to be a surface-controlled reaction.
The adsorption and oxidation of catechol and hydroquinone by Fe and Mn oxides has been investigated by Fourier transform infrared spectroscopic (FTIR) analysis of the adsorbed molecules and by the measurement of O2 consumption by aqueous suspensions of these oxides. Evidence for direct coordination of catechol and salicylate to surface Fe3+ on iron oxides was obtained by FTIR. The promotion of catechol and hydroquinone oxidation by Fe and Mn oxides was confirmed by measured rates of O2 consumption and by the appearance of Fe2+ and Mn2+ in the solutions. However, only trace levels of soluble Fe2+ were detected, suggesting that oxidation by Fe(III) oxides was catalytic in that electron transfer between the phenols and Fe3+ generated Fe2+, which was rapidly reoxidized by O2. Other adsorbates introduced into these oxide/phenol systems, such as acetate, phosphate, and Cu2+, diminished O2 consumption rates, but the effect was generally attributable to a Iowered pH that inhibited oxidation. A model of surface oxidation by Mn and Fe is presented in which coordination of the organic at the surface is a prerequisite to electron transfer. Oxidation of organics can proceed with or without the uptake of O2, depending largely on pH, which determines the rate of reoxidation of the reduced metal ions by O2. The results emphasize the difficulty in interpreting the effects that chemical buffers have on oxidation reactions at oxide surfaces.
The traditional nonthermodynamic Gapon exchange selectivity coefficient (KG) for Na-Ca exchange has previously been shown in the literature to be in close agreement with the Vanselow coefficient (Kv) for Na equivalent fractions (NNa) in the exchange of <0.20. Furthermore, it has previously been shown for a heterogeneous group of soils that the traditional empirical ESP-SAR relation (ESP = NNa × 100; ESP = exchangeable sodium percentage and SAR = sodium adsorption ratio) is indistinguishable from the ESP-SAR relation predicted by the Vanselow equation for NNa <0.40. This study is a sensitivity analysis of the comparison between the Kv and KG for Na+ replacing Ca2+ in the exchange phase. It is carried out by mathematically deriving and graphically demonstrating the interrelationships between Kv and KG. These interrelationships are established on the basis that the Na-Ca exchange system obeys ideal solid solution theory and thus Kv is reduced to a thermodynamic exchange constant. The results point out that generally, the greater the Kv, the greater the NNa range for which an apparent linear relationship between NNa and SAR is observed. This relationship, however, does not ensure that for the same NNa range the condition KG ≃ Kv is also met. The results show that as NNa approaches 0, KG = 0.50 Kv, and as NNa approaches 1, KG approaches infinity. The results also demonstrate that the condition KG ≃ Kv is dependent on the magnitude of Kv or KG for a limited NNa range, and it is independent of the magnitude of the cation exchange capacity (CEC). The condition KG ≃ Kv appears to have the potential to be met experimentally for Kv values in the range of <0.015 and up to a NNa value of approximately 0.60. At the larger Kv values (≫0.015), the condition KG ≃ Kv is less likely to be met because the absolute difference between Kv and KG is significant even at NNa values <0.20. The Kv, however, is always equal to the KG at NNa = 0.60. This cross-over point is independent of the magnitude of Kv and CEC.
A method is described that measure empirically the highly reactive portion of Al in 50 to 1000-uL soil "solution" samples such as those removed from field moist soil by pressure, centrifuging, immiscible displacement, or lysimetry. Three categories of Al reactivity are identified in a single sample: rapidly reacting (RR Al), moderately rapid (MR Al), and total reactive Al (TR Al). Compared with other operational kinetic methods for labile Al, this method is applicable to small samples and is quick, simple, and precise because measurement is integrated over a period of minutes rather than confined to a single time point observation. Correcting for Fe interference does not require reduction and complexation procedures that alter Al speciation. Because of its sensitivity to very small changes in reactivity of Al, this method should be useful for the experimental evaluation of possible increases in mobility of biologically active soil Al, such as those hypothesized to be induced by acid precipitation.
Previous studies by the authors on the effects of pH, organic acids, ionic strength, and Ca on residual orthophosphate solubility in an acidic montmorillonitic soil (Typic Chromoxererts) were extended to include the variation of reaction time. The objective of the experiments was to determine the time dependence of the reactions and to elucidate further the mechanism of orthophosphate solubility in a montmorillonitic soil separate containing exchangeable Al and added citric acid, and suspended in 20 mol NaCl m−3. In the absence of added organic acids, soluble orthophosphate and Al3+ activities were found to be consistent with the presence of an amorphous hydroxy-Al-phosphate solid at elapsed t ≥ 24 h. Initial citrate concentrations of 10, 100, and 400 mmol m−3 resulted in citrate sorption by the soil separate and an increase in soluble orthophosphate and Al for t ≤ 1 h. Citrate sorption continued throughout the time course of the experiments. For 1 < t < 8 h, orthophosphate solubility was not affected by the initial citrate concentration. For 8 < t < 27 h, orthophosphate solubility decreased to constant levels. Soluble Al decreased for 1 < t < 30 h and then remained constant in the 10 and 100 mmol citrate m−3 treatments. The samples reacted with 400 mmol citrate m−3 exhibited a steady increase in soluble Al for the same time period. The time-dependent changes in aqueous orthophosphate and Al were consistent with a previously proposed reaction describing organic ligand-induced formation of an insoluble hydroxy-Al-phosphate. The time trends in the solution concentrations of Ca and Si were not affected by the addition of organic ligands nor were they related to the changes in soluble Al or orthophosphate.
Movement of 54 Mn was investigated in calcareous soil columns (untreated, partially depleted lime, salinized, and sterilized) leached with 0.05 mol CaCl2 L−1 followed by 0.03 mol EDTA L−1 (ethyle-nediaminetetraacetic acid). Manganese was monitored along the soil columns using gamma spectrometry and measured in the effluent during the leaching course (80–120 d). Results indicated that the leaching with CaCl2 for 45 d left 63, 32, and 10% of the applied Mn in the upper 0.5 cm of the silty clay, loam, and loamy sand soils, respectively, with no Mn detected below 5.0 cm. Conversely, leaching with EDTA for 4 d resulted in a nearly uniform distribution of Mn in the 20-cm soil columns. The various soil treatments caused a reduction in the retention capacity of the three soils for Mn with the maximum reduction occurring in the soils with partially depleted lime. In most cases, leaching with CaCl2 for 45 d produced no Mn in the column effluent except negligible amounts of Mn that were displaced from the sterilized and 50 g lime kg−1 columns. On the other hand, Mn emerged in the effluent immediately after EDTA application and continued until the end of the leaching course. The shape and the position of the breakthrough curves varied depending on the specific soil treatment.
The influence of sample size on the magnitude and variability of soil denitrification was studied by collecting soil cores, ranging in size from 1.7 to 5.4 cm in diameter, from no-till and conventionaltill corn plots. Estimates of natural denitrification rates were obtained by incubating intact soil cores with C2H2 and monitoring gaseous N2O production. In addition, maximum denitrification potential was determined by monitoring N2O production in anaerobic slurries amended with glucose, NO-3 and C2H2. Natural rate estimates were highly skewed and approximated lognormal distributions. The spatial variability of denitrification was characterized by large variation at small distances of <10 cm and only weak spatial dependence at distances of 10 to 100 cm. Studies of the effect of sample size on denitrification suggest that soil cores >4.2 cm in diameter yielded the most reliable estimates of natural denitrification rates. Using a computerized random resampling technique, we estimated that approximately 10 to 15 kg of soil was necessary to obtain a representative soil mass for estimating natural denitrification rates. The results of this study are consistent with the hypothesis that the source of variability associated with the natural denitrification rates is the patchy distribution of denitrifying "hot spots" in soil. Some implications associated with the application of classical statistical methods to lognormal data are also discussed.
The objective of this work was to evaluate several mathematical models for describing N mineralization in three arctic tundra soils (Histic Pergelic Cryaquepts) as functions of time and temperature. Intact soil cores were collected in the field and incubated in a laboratory at 5, 15, 25, and 35 °C for 11 weeks. The exponential equation fit the data well at 35 °C but was generally unsuited for describing N mineralization at lower temperatures. The parabolic equation better fit the N mineralization data than the exponential equation except in a few cases where the data appeared to be approaching an asymptote. The parameters of the parabolic equation did not follow simple trends with respect to temperature, however, which made interpolating between experimental temperatures difficult. A second-order polynomial equation with respect to both time and temperature was evaluated. This empirical equation gave R2 >0.98 in all but one case. The major advantages of the empirical, polynomial equation are that it assumes little about the nature of the N mineralization process, it is flexible, and it is accurate. The temperature data did not follow the Arrhenius relationship nor have a simple overall Q10 value because the mineralization rates at different temperatures did not follow similar trends with respect to time. Only a small fraction of the N that is potentially mineralizable is likely to be mineralized under the prevailing cold temperatures of these arctic soils.
The concept of potentially mineralizable N is discussed and data that support the identification of N0 as an active fraction of soil organic N are presented. Aerobic medium-term incubations (13 weeks) were used to measure the potentially mineralizable nitrogen (N0) in four cropping systems on four different occasions from early spring to late autumn. The cropping systems consisted of barley (Hordeum distichum L.) with no N fertilizers (B0), barley receiving 120 kg N ha−1 yr−1 (B120), meadow fescue (Festuca pratensis Hudson) ley receiving 120 + 80 kg N ha−1 yr−1 (GL), and lucerne (Medicago sativa L.) ley with no N additions (LL). The amounts of N mineralized during the 13-week incubations (37°C) ranged from 188 to 483 kg N ha−1, and the cropping systems ranked in the order GL > LL > B120 > B0 and showed a steady decline in all systems from spring to harvest and a subsequent increase from harvest to autumn. The seasonal differences were as large as the differences between systems. Three related models were employed to describe the kinetics of N mineralization during the incubations: (i) first-order, (ii) two-component (sum of two first-order models), and (iii) a simplified special case of the two-component model. In all cases, the special case of the two-component model offered the best description of the curves of accumulated mineral N. Based on the mineralization course and an observed relationship between literature values of N0 and the rate constant (k), it is hypothesized that the mineralization is mediated by two distinct populations: an opportunistic, mainly immobile, population (bacteria) and a generalistic, mobile one (fungi), and that the k value is influenced both by the amount of substrate and its quality. The fact that the amount of mineralizable N decreases during the growing season and increases in autumn as a result of organic matter input provides evidence for the existence of an active fraction of soil organic matter.
Plant phenolic acids have been found in plants and soils and some evidence suggests their involvement in biochemical interactions between plants (allelopathy) and organisms living in the soil. This study was conducted to compare the more common extraction procedures used in the recovery of water-soluble phenolic acids from soil. Various extraction procedures were employed in the recovery of ferulic acid (4-hydroxy-3-methoxycinnamic acid) from steam sterilized soil materials sampled from the A1 and B1 horizons of a Cecil soil (Typic Hapludults, clayey, kaolinitic, thermic) and a Portsmouth soil (Typic Umbraquualts, fine loamy, mixed, thermic). Ferulic acid was added (1000 mg/kg) to soil materials, allowed to equilibrate for 90 d, extracted and quantified by high-performance liquid chromatography. Eight extracting solutions [H2O, methyl alcohol (CH3OH), 0.5 M sodium acetate (CH3CHOONa), 0.05 and 0.5 M diethylenetriaminepentaacetic acid (DTPA), 0.05 and 0.5 M ethylenediaminetetraacetic acid (EDTA), and 2 M NaOH] and various extraction times were used to recover ferulic acid from soil materials. Amounts of ferulic acid recovered from the A1 horizons were significantly lower than the amounts recovered from the B1 horizons for both Cecil and Portsmouth soil materials. Water and CH3OH recovered the least amounts of ferulic acid, whereas NaOH and 0.5 M DTPA recovered the most. In the B1 horizon materials, a major portion of the ferulic acid anions appeared to be absorbed by polyvalent cations (either exchangeable or nonexchangeable). This paper emphasizes the necessity of choosing the appropriate phenolic acid extractant for the soil phenolic acid fraction of interest.
Short-term greenhouse and culture solution studies have shown that P uptake and translocation is regulated by N. The objective of this study was to determine the effect of N rate on P status of corn (Zea mays L.) grown on soils with varying levels of available P in the range adequate for growth. Field experiments were conducted on Dothan (Plinthic Paleudults), Goldsboro (Aquic Paleudults), and Portsmouth (Typic Umbraquults) soils. Nitrogen rates used were 0, 56, 112, 168, and 224 kg N ha−1 supplied as NH4NO3 and urea. Phosphorus was applied at a rate of 22 kg P ha−1. Leaf P concentration at silking was increased by N fertilization and was highly correlated with leaf N concentration. Total Paccumulation was highly correlated with total N accumulation. Available soil P levels had little effect on leaf P concentration and total P accumulation. Nitrogen supply was the main factor affecting the P content of corn on soils with adequate levels of available P.
Field experiments were conducted in two Brazilian orchards to examine the effects of soil applications of calcitic lime (Ca-lime), phosphogypsum, CaCl2, and magnesite (Mg-lime) on soil chemistry and Ca nutrition of apple (Malus domestica Borkh. cv. Gala/MM 106). One orchard was on a low Ca, high Al Inceptisol; the second orchard was on a low Ca, low Al Oxisol. The resulting soil chemical changes were strongly influenced by the initial soil chemistry and the composition of the soil amendments. The effects of Ca-lime, added at a rate calculated to neutralize the topsoil exchange acidity, were restricted primarily to the upper 20 cm of the soil, where it increased pH, increased total dissolved and exchangeable Ca, eliminated dissolved Al, and reduced exchangeable Al. Phosphogypsum, added at Ca rates equivalent to the Ca-lime treatment, slightly reduced soil pH in the Inceptisol and slightly increased soil pH in the Oxisol. Phosphogypsum did not appreciably affect dissolved Al in the topsoil; however, it did reduce exchangeable Al but to a lesser degree than did Ca-lime or Mg-lime. Phosphogypsum increased exchangeable Ca and decreased exchangeable Al in the subsoil to a depth of 40 to 60 cm. Calcium chloride, added at Ca rates equivalent to the Ca-lime treatment, produced dissolved and exchangeable Ca increases similar to the phosphogypsum treatment; however, soluble and exchangeable Al were increased and pH slightly decreased throughout the soil profiles. Mg-lime, added at an acidity-neutralizing rate equivalent to the Ca-lime treatment, produced results similar to Ca-lime except that soluble and exchangeable Mg rather than Ca were increased in the topsoil. Apple tree root densities were enhanced in the soil layers that were made simultaneously high in exchangeable Ca and low in exchangeable Al by the soil amendments. The trees with the more extensive root systems had higher leaf Ca concentrations and produced more and larger fruit. The Ca concentrations in these larger fruit were not reduced by fruit expansion, suggesting enhanced Ca supply from the soil
The uptake of fertilizer P by winter wheat (Triticum aestivum L.) was investigated for four Southern Plains soils in 900-cm2 field plots over 4 yr, to quantify the relative availability and uptake of native, fertilizer, and residual fertilizer P. Statistically significant differences between duplicated treatments were determined by analysis of variance. Winter wheat was harvested 70 d after the September planting. At this time the proportion of soil Bray P from native and residual P increased (3.7- to 4.6-fold) with successive annual fertilizer P applications (30 kg P ha−1 yr−1), while that from fertilizer P remained fairly constant. The uptake of winter wheat P from native and residual P increased and from fertilizer P decreased with successive fertilizer applications, due to an increasing amount of residual P uptake. Residual fertilizer P uptake by winter wheat was distinguished from native soil P and quantified as the difference in uptake determined by nonisotopic and isotopic methods. The nonisotopic method represents the difference in uptake between check and fertilizer P treatments, which will include fertilizer and residual P uptake, whereas the isotopic method represents only fertilizer P uptake. It was thus calculated that uptake of residual fertilizer P increased annually, representing from 4 to 40% of P uptake by winter wheat at harvest. By comparing the amount of wheat P from soil and fertilizer, it was found that the relative availability of native and fertilizer P did not change with continued fertilizer application to the four soils.
Field studies were conducted in 1983 and 1984 at Lexington, KY to examine the effects of N and K fertilizer on yield and chemical quality of burley tobacco (Nicotiana tabacum L. cv. Ky 14). Treatments included: NH4NO3 at rates of 112, 280, and 448 kg N ha−1; and two sources (K2SO4 and KCl), each at rates of 0, 112, 224, and 448 kg K ha−1. The following agronomic and chemical characteristics were examined: yield, price, leaf N, P, K, Ca, Mg, Cl, Mo, total alkaloid, and solanesol concentrations. Cured leaf yield, price, and solanesol concentration were strongly influenced by N × K interactions. Each was raised by increasing N rates when no K was applied; however, at higher K levels, increasing N rates resulted in smaller price increases, no yield changes, and reductions in solanesol concentrations. Reductions in cured leaf Mo concentration relative to N, K, and Mg levels with increasing K fertilization beyond 0 kg ha−1 were exaggerated as N rates were raised. No effect of N rates on total alkaloids or solanesol concentrations were noted while increased K rates increased concentrations of both. Greater cured leaf yields and Mo concentrations were achieved with KCl than with K2SO4. The positive effect of KCl on Mo concentration at low N application rates was reduced by increased N fertilization suggesting that Mo uptake was enhanced by Cl- but reversed at high levels of NO-3 application.
Two minor moraine basins in Story County, Iowa, were examined to determine the extent and effect of postglacial erosion on the present landscape and stratigraphy. Minor moraines are subtle repeating ridge and valley landforms with relief of approximately 2 m. The stratigraphy was examined in this study using grid and transect borings. A mantle of locally derived postglacial sediment blanketed the Late Wisconsinan till in both basins. In places, a strata of coarse diamicton separated the till and sediment. The postglacial sediment was identified primarily on particle size distribution and bulk density. After determining the extent and thickness of sediment in each basin, the sediment volume and mass were calculated. Previously, the Late Wisconsinan till in central Iowa was dated as being deposited 14 000 RCYBP (radio carbon years before present). This age was used to calculate a gross annual rate of postglacial erosion. The basin with modern relief of 2.7 m had a 0.9 Mg ha−1 yr−1 erosion rate and the basin with modern relief of 1 m had a 0.7 Mg ha−1 yr−1 erosion rate.
The objectives of this study were to investigate the effects of pedogenesis and landscape position on (i) the association of total P with particle-size content and with various particle-size separates, (ii) relative abundance of different forms of P, and (iii) P distributions between horizons and soils representing five landscape positions on an Ultisol hillslope in northwest Florida. Total-P content in soil seemed to be directly associated with the amount of clay in the lower landscape positions. This association may be the result of the activity of the mineralogy dominant in the clay fraction. Total P in the clay and P-fraction values indicated that some P had been redistributed between horizons and possibly between soils on the landscape. Coarser sands commonly had more total P than finer sand fractions. The sand fractions were composed primarily of quartz and ironstone. The amount of ironstone in the sand fraction was probably responsible for the amount of total P. Among P fractions, a large portion of P was in the residual form, especially in lower horizons, implying that the soils are intensely weathered or developed from parent materials that contained considerable residual-P, which was occluded in sesquioxides prior to deposition of the sediments. The P forms were present in the order of decreasing abundance as residual-P, Fe-P, Al-P, and Ca-P. Water-soluble P was not detected in any of the soils.
The effect of irrigation water quality (salinity) and quantity on the yields of sweet corn (Zea mays cv. Jubilee) and cotton Gossypium hirsutum L. cv. Acala SJ-2) was studied in a sandy loam (Typic Torrifluvent) soil. For each of the irrigation water salinities of Co = 1.8, 3.6 and 6.7 dS/m (for corn) and Co = 3.6, 6.7, and 10.5 dS/m (for cotton), 10 amounts of irrigation water (Q) ranging from 0.15 to 2.7 times the class A pan evaporation (Eo) were applied via trickle irrigation. Root zone soil-water matric potential, water content, and salinity were monitored, and corn and cotton yield components were measured. Time-averaged root zone soil water content (θ) and soil salinity (EC), as well as crop yield components (Y) were affected by both Q and Co. Results of the analyses of the crop-water production functions suggest that increasing the amount of irrigation water may compensate only in part for the adverse effects of the salinity of the irrigation water. For corn, using irrigation water of Co = 3.6 and 6.7 dS/m, maximum ear yields were reduced by 8 and 27%, respectively, relative to the maximum ear yield obtained using water of 1.8 dS/m. For cotton, using irrigation water of Co = 6.7 and 10.5 dS/m, maximum seed cotton yields were reduced by 6.5 and 30%, respectively, relative to the maximum seed cotton yield obtained using water of 3.6 dS/m. Analysis of the Y(θ, EC) relationship for each of the corn and the cotton yield components suggested that, due to the mutual effect of θ and EC on Y, the crop response to salinity curve is affected by θ and, in general, should be described by a nonlinear concave expression rather than by the piecewise linear expression of Maas and Hoffman (1977).
Objectives of this research were to (i) develop statistical models for predicting water content at three matric potentials, using three levels of input data; (ii) compare predictive capability of the locally calibrated models with those of three published models; and (iii) illustrate the changes that occur in water retention when texture of sandy soils is altered by deep plowing or wind erosion. At −10 kPa, accuracy of predicting gravimetric water contents increased with increased number of inputs. The R2s and the slopes between predicted and measured water contents for 50 samples increased, and the intercepts came closer to zero as the inputs progress from clay only to soil texture plus organic matter and CaCO3 and on to sand separates plus texture, organic matter, and CaCO3. At the −33- and −1500-kPa matric potentials, the clay-only model predicted soil-water content equally as well as the two local models with more inputs. A previously published clay-only model that had been calibrated using semiarid soils performed almost as well as the locally calibrated models. Two other published models performed unsatis-factorily in predicting water retention at any of the matric potentials. Deep plowing increased clay content of one specific soil from 4 to 14%. Wind erosion subsequently reduced clay to 6% after 5 yr. Predicted water contents were 0.281, 0.341, and 0.293 kg kg−1, respectively, at −10 kPa, and 0.012, 0.050, and 0.020 kg kg−1, respectively, at −1500 kPa.
Soil erosion from interrill areas is a function primarily of soil detachment by raindrop impact and transport capacity of thin sheet flow. Soil detachment normally is the rate-determining process and is controlled, to a large extent, by surface sealing and crusting. The purpose of this study was to measure the effect of surface sealing on infiltration, runoff, and soil loss for 20 soils ranging in texture from sand to clay. Wash and splash erosion were measured for near-saturated soils in 0.14-m2 Al pans exposed to laboratory simulated rainfall with an intensity of about 63 mm/h for 1 h. For most soils, wash and splash amounts decreased with time due to surface sealing with the decrease in wash being much less than the decrease in splash. Comparing the 20 soils, surface sealing caused a reduction in infiltration rate ranging from 1.2 to 36.0 mm/h and an increase in shear strength ranging from 2.6 to 42.3 kPa, resulting in a decrease in total soil loss ranging from 13.3 to 56.8 g/5 min. Total soil loss, splash, and wash were highly intercorrelated (p < 0.001).
Soil erodibility is often estimated using predictive equations based on easily measurable soil parameters. However, most predictive equations are valid for a limited group of soils and do not account for temporal changes in surface conditions. The objective of this study was to identify those soil properties that affect interrill splash and to develop an interrill detachment model based on both static and dynamic soil properties. Twenty soils ranging in texture from sand to clay were exposed to laboratory simulated rainfall with an intensity of about 63 mm/h. The development of a surface seal decreased infiltration rate, splash, wash erosion, and increased soil strength, as measured with a fall-cone device. The best predictor of soil splash for the surface sealed condition was a combined kinetic energy/fall- cone strength (KE/τ) and total silt content term, and of total soil loss, a KE/τ and coarse silt content term. Comparing results from this study with previously reported studies, we conclude that for improvement of laboratory based indices, greater attention must be given to dynamic soil properties such as the soil's resisting force to raindrop impact and surface flow.
Differences in selected parameters and derived variables of models fitted to soil shrinkage curves were used to investigate soil structural degradation of an irrigated Pellustert in northern New South Wales, Australia. Significant differences between clods taken from the same depths in land prepared for cotton (Gossypium hirsutum L.) when "dry" and "wet" were found in specific clod volume at zero water content, the slope of the line in the normal shrinkage zone, the airfilled specific pore volume throughout normal shrinkage, and the range in water content in the structural shrinkage zone. These indicators showed that this soil prepared wet exhibited increased bulk density, decreased porosity, loss of structural pores, and tended to have weak structural development.
The objectives of this study were to determine if burrows produced by two species of earthworms (Aporrectodea tuberculata and Lumbricus rubellus) found in continuous corn (Zea mays L.) in Minnesota altered the infiltration rate and depth distribution of surface applied water. Each species was introduced (212 m−2) to in situ cylinders in plots initially void of worms that had been subjected to tillage with and without residue or no-till with and without residue for 5 yr. Burrows produced by both species of worms during a 46-d period increased average infiltration rates of 30 mm of water relative to controls after 46 d. Surface residues more than doubled the number of burrows open to the surface relative to incorporated residues (48 vs. 15 for L. rubellus, 37 vs. 15 for A. tuberculata). Cocoon production, an indicator of potential survivability, was present for both species in the no-till-surface residue treatment and for A. tuberculata also in the till-incorporated residue treatment. Bromide (Br-) tracer and mass balance for Br- in all treatments showed infiltration and Br- movement in the upper 5 cm of the profile was fastest in tillage treatments with worms and residues and that Br- movement beyond 19 cm was greatest for the no-till treatments with worms and residues. Pore continuity and survival potential for worms in the no-till-residue treatment suggest that this treatment might increase populations of worms in cropland while altering the hydraulic status and erosion susceptibility of soils in the north central USA.
Conservation tillage, particularly no-till (NT), for corn (Zea mays L.) production on poorly drained soils in the U.S. Corn Belt often produces lower yields. Cone index (CI), bulk density (ρb), shrinkage, hydraulic conductivity (Ks), and water release charcteristics were all measured in a Typic Haplaquoll under NT and conventional tillage (CN) to characterize soil physical factors possibly related to the lower yields. Measurements in the interrows indicated that wheel traffic, associated only with crop establishment (planting and herbicide spraying), eliminated the benefits of lower CI and greater Ks associated with primary and secondary tillage. Cone index was a more sensitive indicator of these trafficking effects than was ρb. With the exception of the surface layer (0.0–0.1 m) of untracked interrows, Ks values under NT, as measured in vertically oriented soil cores, exceeded those in CN profiles. Because these tillage effects were not observed when Ks was measured in situ using a permeameter that integrated horizontal and vertical components of Ks, the high Ks measurements from cores were probably produced by flow in vertically oriented macropores although interfacial flow between sample ring and soil cannot be discounted. Untracked NT and CN surface layer macroporosities amounted to 5 and 0% of total porosity, respectively. Macropores did exist below the surface of the tilled layer, but they were susceptible to destruction by wheel traffic. However, tillage did not affect tile drain performance.
The effect of an organic super gel commercially called Jalma (containing 24% humic acids, and 3.8% polysaccharides) at rates of 0.0, 0.4, 0.8, and 1.6% on aggregation index (AI) and relative swelling index (RSI) of loamy sand, sandy loam, and clay loam soils was studied. Furthermore, the influence of these rates and two irrigation intervals, 7 and 14 d, on intermittent evaporation from surface-treated soil columns were also investigated. Twenty-two or 44-mm of water were applied every 7 or 14 d, respectively. The soil columns were placed in a walk-in controlled growth chamber with potential evaporation of 8.2 mm/d. Addition of 0.4% Jalma significantly increased AI of the three soils by 33 to 38%. Increase of the Jalma rate to 0.8% significantly improved the AI of the fine-textured sample but not the coarse-textured samples. Further increase to 1.6% had no significant effect on the AI of the three samples. The lowest rate of Jalma significantly increased RSI of the three samples. The results also indicated a sharp, significant increase in RSI with increase in Jalma rate to 1.6%. In general, Jalma treatment significantly reduced cumulative evaporation and hence increased the amount of water conserved (AWC) after the first wetting/drying cycle. After four evaporation cycles, on 0.4% treated loamy sand, sandy loam, and clay loam soils, the AWC values were, respectively, 4.3, 3.2, and 1.5 times that of the untreated soils. The AWC values for untreated loamy sand, sandy loam, and clay loam soils irrigated every 14 d were, respectively, 2.6, 1.7, and 1.6 times those irrigated weekly.
The accumulation of P in sediments deposited within riparian areas was measured to study the role of these areas as P sinks. The sediments originated from the cultivated fields and forests of the uplands and were deposited during the last 20 to 25 years. The riparian areas were studied in the Atlantic Coastal Plain and consisted of four field-forest edges, four ephemeral streams and four flood plains of intermittent streams that flowed into a flood plain swamp. Selective sorting and deposition of sand and silt near the field-forest edge (0–20 m) and clay deposition downstream (1–4 km) on the flood plains and swamps explained much of the total P distribution in the riparian areas. The P in the sediments increased with percent clay, R2 = 0.80. Laboratory measurements of the equilibrium phosphorus concentration (EPC) in flood plain swamp sediments were two to three times higher than P concentrations in the overlying water (1.0 vs. 0.4 µmol P L−1) during high flow stages of winter and spring. During summer and fall the ortho-P concentrations of isolated pools and base flow ranged from 1.0 to 1.3 µmol P L−1. Approximately 260 kmol of P were deposited in the riparian areas of the 1850 ha watershed during the past 20 to 25 years. The amount of P deposited was equal to the amount estimated to have been removed from the watershed in the drainage water. Thus about 50% of the P leaving agricultural fields appeared to be removed from the runoff water in the riparian areas. Riparian areas between the field edge and a perennial stream were sinks for P because of the continual deposition of fresh sediment from upland areas.
Computer simulation models are needed to help describe the dynamic nature of soil-water regimes. A simple water budget and an integrated soil-plant-atmosphere simulation model (NTRM) were each evaluated for predicting water regimes under no-till (NT) and conventional tillage (CN) of a well-structured soil. Estimates of soil physical properties related to the retention and movement of water, which were required as input for the models, were obtained from laboratory measurements on undisturbed soil cores. An in situ drainage experiment, using Br- labeled water, also provided information on field capacity water retention properties. Ponded water containing Br- moved rapidly through the surface 0.5-m profiles of both tillage treatments. Redistribution of the added water was effectively completed within about 8 h. Field capacity matric potentials of both profiles were above −6 kPa. Chromatography theory indicated that the labeled water may have mixed with only 43 and 25% of the initial soil water in the CN and NT profiles, respectively. Despite these observations, both models, which assumed complete mixing within each soil layer, were reasonably satisfactory at predicting soil-water contents under corn (Zea mays L.) through the 1984 growing season at a southern Minnesota location. Output from the NTRM model agreed better with experimental data showing water contents lower under CN than NT.
Fifteen highly weathered Alfisols and Ultisols from Georgia were used in runoff/erosion pan studies to delineate sediment character istics of interrill-eroding soils and their relationship to soil particle size. Simulated rainfall was applied to the pans at 11.2 cm h−1, and runoff and sediment parameters were measured at 5-min intervals for 25 min. Runoff rates and sediment concentrations varied consistently over time for the soils used, with concentrations increasing until peaking at 10 to 15 min, then decreasing as crust formation caused surface consolidation and decreased detachability, despite continued high runoff rates for most of the soils. Sediment particle size became finer after the initial sampling period, and was dominated by silt-sized particles, with lesser amounts of primary clay and sand. Silt-sized particles in the sediments were related statistically to a measure of water-dispersible (0.5-h shaking) soil silt, whereas primary sediment clay was related to both water-dispersible (36-h shaking) and total soil clay. Dispersible and total soil clay were also correlated with sediment concentration and soil loss rate, emphasizing the role of clay and its dispersibility in erosion and crust formation on these soils. A quadratic equation using soil clay described sediment clay content, showing greater relative enrichment of primary clay in sediments from sandy vs. clayey soils. The high proportion of easily transportable sediment generated by interrill erosion on these soils poses a serious environmental problem in areas of active soil erosion.
Nylon net litterbags (30 by 30 cm) containing ∼10 g of upland oak leaf litter were collected at 30-d intervals over a 1110-d period from two upland oak (Quercus sp.)-mixed hardwood stands on the Cumberland Plateau of Tennessee. Statistically significant differences (P ≤0.01) in losses of mass, N, K, Ca, and S were found between sites, whereas P and Mg losses did not differ. Litterbags containing mesic mixed-hardwood leaf litter were collected at 30-d intervals over a 810-d period from mesic mixed-hardwood stands located on the same watershed study sites as the upland oak stands. Statistical comparisons indicated significant differences in mass, N, P, K, Ca, Mg and S loss between sites. Constant rate projections of the time required for the upland oak litter weight to reach 10% of the original bag content based on 365, 730, and 1095 d of data were 960, 1530, and 1770 d, respectively, at the Camp Branch Watershed and 870, 1230, and 1410 d at the Cross Creek Watershed. Estimates of decomposition times derived from constant rate projections for both cover types were considerably less than observed values. In an attempt to obtain more realistic projections of weight and nutrient loss, several mathematical models commonly used to examine decomposition data were evaluated. A modified exponential model gave the best data fit and provided estimates of 3240 and 2370 d as the time required to reach the 10% mass-remaining value for the upland oak litterbags at Camp Branch and Cross Creek, respectively. Estimates for the mesic mixed-hardwoods were 1590 and 2490 d at Camp Branch and Cross Creek, respectively. The weight of most nutrients in the litterbags was modeled with limited success by the modified exponential model. However, N and particularly P weights could not be described by the model since they generally increased with time ove rthe study period. The results of this analysis, in addition to suggesting that a longer time is required for decomposition than is normally projected, also suggest that a single model may not be appropriate to describe all response variables. Data presented here along with the modeling work also reiterate the fact that a decay rate derived from a single species or group of species must be applied with caution over larger landscape units because of the potential differences both within and among sites.
This study focused on the effect of Gambel oak (Quercus gambelii Nutt.), a common subdominant and understory species in a ponderosa pine (Pinus ponderosa Laws.) forest in central Arizona, on selected nutrient properties of the forest floor and soil. Samples of the L, F, and H layers (Oi, Oe, and Oa horizons, respectively) of the forest floor and the 0- to 5- and 5- to 15- cm layers of mineral soil from 33 randomly selected stands of ponderosa pine with varying amounts of Gambel oak (from 0 to about 75% of total basal area) were collected and analyzed for total N, P, S, total and exchangeable Ca, Mg, and K, and organic C. Chemical properties of fresh litterfall suggested the potential for oak to strongly influence soil fertility of the pine forest. In the forest floor as a whole, only C and Mg concentrations were not positively correlated with oak basal area. In separate layers (L, F, and H) of the forest floor, the concentration of all measured nutrients increased with oak. Increases in nutrient concentration for these layers ranged up to 133% for K in the H layer at 70% oak basal area. Increased oak influenced C and N concentration more than other nutrients in the 0- to 5- and 5- to 15- cm soil layers. Increase in oak basal area to 70% resulted in a downward shift (i.e., redistribution) of C, N, P, and S within the forest floor. Hence, these nutrients were more heavily concentrated in the H than in the L and F layers with increases in oak from 0 to 70% of total basal area. Elemental ratios (C/N, C/P, C/S, C/Ca, C/Mg, and C/K) for all layers of the forest floor declined sharply as percentage oak basal area increased.
To study effects of acidic atmospheric deposition on woodland soils in the Netherlands, chemical budgets were determined from simulated water fluxes and measured soil solution concentrations. Solute concentrations were determined in soil solutions that were sampled monthly over a 3-yr period at various depths in four different soils. Soil-water fluxes were calculated with the SWATRE model. Rainfall and canopy troughfall were measured at the study site. Potential evapotranspiration was estimated by an adapted Penman method. Hydraulic conductivity was calculated from the soil-water retentivity curves according to the Van Genuchten method. Simulated pressure heads could be fitted to field observations after reduction of conductivities by a factor between 6 and 60. Coefficients of variation for chemical budgets were determined by sensitivity analysis of the simulated soil-water flux, and by measuring spatial, temporal, and analytical variability of the solute concentrations. Coefficients of variation of solute fluxes for Al and NO3 ranged from 10 to 30% between the 10- and 90-cm depth, with spatial variability as the most important source of uncertainty. Coefficients of variation of chemical budgets (difference between inputs and outputs of solutes) for soil compartments that include the soil surface were also 10 to 30%, whereas those for deeper soil layers were larger, ranging from 40 to 200%.
Inorganic N budgets were estimated for four oak-birch (Quercus robur L.-Betula pendula L.) woodland soils in the Netherlands, that receive high inputs (40–60 kg ha−1 yr−1) of atmospheric N, mainly as (NH4)2SO4-. Budgets were based on measured inputs in through-fall water, measured soil solution concentrations, and simulated soil-water fluxes. Substantial nitrification occurred in both highly acidic (pH 3–4) and calcareous (pH 6.5–7.5) soils. The acidity formed during N transformations (3–9 kmolc ha−1 yr−1) accounted for a major part of all soil acidification taking place. Extreme soil acidification due to nitrification (4–14 kmolc ha−1 yr−1) in the 10-cm surface soil in three of the four plots was partly alleviated at greater depth by removal of NO-3. Presumably, most of this NO-3 was removed by plants and microorganisms and, perhaps, in part by denitrification. In two of the four soils, leaching of inorganic NO-3 exceeded atmospheric throughfall input. This trend indicates that N inputs were still higher, e.g., due to direct assimilation of atmospheric NH3 by tree leaves, or that the pool of soil N decreased by mineralization in excess of uptake. In one of the four soils, most of the atmospheric N2 was assimilated and soil acidification due to N transformations was relatively small. The differences in N budgets and associated soil acidification may be related to (i) consistent differences in N input over many years, and (ii) differences in accumulation of N in biomass. Variation in these two factors may be responsible for differences in the degree to which the ecosystems are now "saturated" with N.
Annual element budgets for three acidic oak-birch (Quercus robur L.-Betula pendula L.) woodland soils in the Netherlands indicate high inputs of atmospheric (NH4)2SO4 (2.35–3.45 kmol NH4 ha−1 yr−1). Nitrogen transformations lead to strong acid inputs of 3.0 to 7.5 kmolc ha−1 yr−1 in these soils, which are neutralized primarily by solubilization of Al in the surface 20-cm mineral layers (3–7 kmolc ha−1yr−1). We hypothesize that Al was relatively important in neutralizing strong acid inputs, due to the high acid loading and the low content of base cations. At the low pH (pH 3.27–4.26) dissolved Al in the mineral soil was mainly in aquo-Al3+ form. Highest Al concentrations (up to 4 molc m−3) were reached in summer and coincided with high NO-3 concentrations. In winter and spring, the export of Al with drainage water peaked and solute concentrations decreased. All Al mobilized in the surface layers of soil A was retained below the 40-cm depth, probably due to cation exchange, since below this depth base saturation increased. In the deeper horizons of soils B and C, immobilization of Al was less, probably because base saturation was low. All subsoil solutions were undersaturated with respect to gibbsite and near equilibrium with jurbanite. Formation of jurbanite is unlikely, however, because mass balance calculations do not indicate net SO4 retention.
A 12-yr study was conducted on four Mollisols in Nebraska to evaluate response of corn (Zea mays L.) and wheat (Triticum aestivum L.) to P and K fertilizers and to determine the rate of buildup or decline of these nutrients in soil. Rates of P were 0, 11, 22, and 33 kg ha−1 applied annually or in less frequent applications of higher rates in order to maintain the same average seasonal amount, along with 27 and 54 kg annual K rates ha−1 in association with 22 kg P. The P and K fertilizers were broadcast and incorporated before planting with an appropriate blanket N treatment for the two crops. Positive yield response to applied P resulted when soil test P by Bray and Kurtz no. 1 procedure was below 15 mg kg−1 for corn and 22 mg kg−1 for wheat. No positive yield response to applied K was measured in these soils of high exchangeable K but rather a yield depression was observed at the high K rate. No significant differences in yield existed between annual applications of P and the heavier less frequent applications. Soil test P level was maintained by annual P rates of 4 to 13 kg ha−1 on the eastern soils, with none applied in the west, and was more than doubled on all soils at the end of the experimental period with 33 kg applied. Three of the soils evidenced distinct increases in soil test K without K application; the fourth a slight decline. Results from P fractionations of the test soils are reported to aid in interpreting the yield results.
Field experiments were conducted to test the efficiency of calcium cyanamide (CaCN2) as an N source for wheat (Triticum aestivum L.) and maize (Zea mays L.) over four cropping seasons at the Irrigation Research Station at Kadawa (10°39′N, 08°02′E) Nigeria. Calcium cyanamide applied at recommended N rates, was compared with urea (120 kg N ha−1) and a mixture of urea and CaCN2 [urea (110 kg N) plus CaCN2 (10 kg N ha−1)]. Highest maize grain yields and N uptake were obtained with the mixture of urea and CaCN2 in both years of the study. Wheat yields were unaffected by form of N. Recovery of inorganic N (NO-3 + NH+4) in the surface soil, 8 weeks after planting wheat in 1984 to 1985, was greatest for the CaCN2 treatment followed by the urea-CaCN2 mixture, and urea in tha torder. Nitrogen recovery in the 0.6-m depth was approximately the same for all treatments. A laboratory incubation study using the same soil gave about 80% recovery of inorganic N from added CaCN2 within 8 weeks with most of the N remaining as NH+4 throughout the 8-week study. Addition of 10 mg kg−1 of N as CaCN2 to the soil inhibited the nitrification of added urea.
A combination of finely ground phosphate rock (PR) and triple superphosphate (TSP) represents a method that can improve the agronomic value of PR at a lower cost than would be required to manufacture the conventional, fully acidulated fertilizers from that same rock. A reactive PR from North Carolina was evaluated for its effectiveness as a P source when used in conjunction with TSP at P rates up to 266 mg P kg−1 in a short-term (6-week) greenhouse experiment. The soil used was a limed Mountview silt loam (Typic Paleudult) with pH 6.2. As measured by dry-matter yield and P uptake, P availability from PR appeared to increase with increases in the proportions of TSP to PR in the TSP-PR mixtures. Although PR alone was less effective than TSP, PR was just as effective as TSP when mixed with TSP at a P ratio of at least 1:1. Because plants responded to both TSP and PR, and because there was an interaction between TSP and PR in the soil, neither water solubility nor total citrate solubility could be used to predict the effectiveness of TSP-PR mixtures with different P ratios.
The alkylammonium method of characterizing the charge of layer silicates has recently been applied to soil clays containing mixed mineral assemblages. Various sharp, low-angle x-ray diffraction (XRD) peaks (e.g., 2.5 nm for tetradecylammonium-treated samples) have been attributed to vermiculite or high-charge smectite. To the degree that alkylammonium cations can replace interlayer K+, however, the observed low-angle peaks may represent K+-depleted soil illite as well as vermiculite. This hypothesis was tested by treating two reference illites with alkylamine hydrochlorides. The treated illites exhibited low-angle XRD peaks similar to those observed in the soil clays. Moreover, the occurrence of these low-angle peaks coincided with the release of K+ from the illites. Similarly, the alkylamine hydrochloride treatments for layer-charge determinations released as much as 49% of the K+ from a soil clay. These data clearly show that the alkylammonium method can expand soil illites to give low-angle XRD peaks, which may be misinterpreted as evidence of soil vermiculite.
Octahedral Fe(III) in the crystal structures of three different smectites was reduced to Fe(II) by actively growing microorganisms indigenous to the clay. The smectites were SWa-1 ferruginous smectite from Grant County, Washington; API 33a, Garfield Nontronite; and API 25, Upton montmorillonite. Bacterial growth was supported by incubating clay suspensions at room temperature in a nutrient broth solution consisting of peptone and beef extract. Some samples were first sterilized (by autoclaving), then seeded with bacteria that had been isolated previously from the SWa-1 sample. The effect of O2 on microbial reduction of Fe(III) was also tested. Results revealed that, in all three clays, about 0.30 mmol Fe(III)/g clay was reduced to Fe(II) by bacteria in a 28-day period. The specific organism responsible for Fe reduction has yet to be classified, but it was more efficient in samples that had not been purged of O2, and it appears to be indigenous to the SWa-1 clay.
Deeply weathered soils forming on andesitic mudflows are common in the foothills of the Sierra Nevada of California. Many of these soils (Humults) have oxidic mineralogy based on extractable Fe and gibbsite detected by x-ray diffraction and differential thermal analysis. Thermal analysis and differential thermal analysis of whole soil samples reveal kaolin and gibbsite percentages greater than clay percentages obtained by particle-size analysis. X-ray diffractometry of the fine (0.1–0.25 mm) and coarse (0.5–1.0 mm) sands shows fractions dominated by kaolin throughout the profile. Halloysite predominates in the saprolite; kaolinite increases in abundance toward the soil surface. Gibbsite is present in the surface and upper argillic horizons. Observation of the fine sand fraction with a polarizing light microscope reveals highly weathered feldspar grains with very low birefringence. Scanning electron micrographs of coarse and fine sands show pseudomorphic replacement of feldspar by halloysite resulting in discrete sand-sized grains wherein simple albite twins are preserved. Energy dispersive analysis by x-ray of unweathered feldspars produces Si/Al count ratios of 6:1 and indicates the presence of K and Ca in the feldspar structure. Analysis of the surfaces and interiors of kaolinized feldspar grains shows Si/Al count ratios of 2:1 and an absence of K and Ca, demonstrating that the feldspars are completely altered to kaolin by desilication and loss of hydrolyzable cations. The alteration appears to be crystallographically controlled because the original feldspar crystal morphology is preserved.
The clay mineralogy of Coastal Plain soils with sandy epipedons was studied with respect to taxonomic class, horizon, and the presence or absence of sand grain coatings. Relative estimates of claysized minerals were based on x-ray diffraction peak height ratios after calibration with standards and normalization. Clay mineralogy of sandy horizons was related to whether the clay occurred as grain coatings or as loosely adhering floccules. Clays from coated (⩾5% silt + clay) and slightly coated (<5% silt + clay) sands were consistently high in hydroxy-interlayered minerals (HIM), and usually contained gibbsite. Clays from floccules in the matrix of stripped (coating-free) sands contained large amounts of quartz, variable smectite, little or no HIM, and no gibbsite. Mineralogical differences between clays associated with stripped sands vs. coated/slightly coated sands were highly significant statistically. Clay mineralogy of coated/slightly coated sandy horizons was similar regardless of taxonomic class or horizon depth. The A and E (stripped) horizons of Haplaquods were similar to stripped Quartzipsamment horizons in being depleted in HIM relative to other phyllosilicates. Haplaquod Bh and E′ horizons (coated to some degree) were relatively high in HIM and therefore were mineralogically similar to coated/ slightly coated Quartzipsamment horizons and to Arenic and Grossarenic Paleudult epipedons. Clay fractions from chemically reduced loamy horizons of Paleudults and Haplaquods were depleted in HIM relative to overlying coated sandy horizons. Results suggest that pedogenic processes that promote the destabilization of grain coatings (i.e., podzolization, chemical reduction) also promote the loss or redistribution of HIM associated with these coatings.
A sampler was designed and tested for extracting 60- by 53-mm (length by depth) undisturbed core samples from subsoils. The sampler consists of a sample cylinder "barrel," and an "adaptor block" for fitting the barrel to the end of a 76.1-mm o.d. hydraulic probe tube. Samples are taken by augering to the desired depth, and using the tube and sampler assembly to extract the sample. The tube and sampler assembly can also be used with a protective steel anvil to remove samples in shallow subsoils without a hydraulic probe. Samples on sands have been taken as deep as 2.5 m using the hydraulic probe, and as deep as 0.61 m using the anvil and maul method.
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