The Dirt on Soil

Saturday Morning Fun Times Ideas

2011-12-01T21:00:00.000-08:00

Info thanks to the Capital Area Master Naturalists (CAMN)!

Biodiversity Survey

Austin Nature and Science Center

Saturday, Dec. 3, 2011

8:00 am

Biodiversity = the variety of all forms of life, from genes to species... (Stanford Ecyclopedia of Philosophy)."
Survey = to look carefully and thoroughly at someone or something; a non-experimental, descriptive research method.

Nohhhhhtes: No special skills are required, and all are welcome. Dress comfortably; long pants and sturdy shoes with closed toes, hat, water bottle, and sunscreen are stongly recommended. We may encounter ticks, mosquitoes, &/or poison ivy, so arm yourselves accordingly! For your personal use, you may wish to bring field guides, notebook and pen, camera, and / or binoculars.

Changes are sometimes necessary, so if you would like to join us, please contact Melissa Macdougall melissa.jane.mac@gmail.com or 422-6270.

Man-Eating Plants and an Announcement

2011-08-13T21:39:00.000-07:00

Hi Readers!
Do you know how I told you that this blog is about science in Austin, TX? Well... not today! Cuz I visited Maryland over the summer, so you get Maryland science today. Yay! Here is something I saw in Maryland:

Man-Eating Plants:
I was with la familia at the Deep Creek Lake, and in an effort to ~~wear out and produce a nap~~ educate our son, we went hiking at Cranesville Swamp*. Here is the back of his head at the swamp...

And upon looking at that picture, here is the drama I imagine would enfold if we were face-to-face:

You: Amanda, I love you and all, but that is not a swamp. That soil looks really dry. Swamps aren't dry, they are forested wetlands.

Me: You! I sooo love you too! You are right. The swamp didn't fit into this picture; it is up ahead, on the right.

So anyway, the super-cool reason we went to the swamp is because... there are man-eating plants!!! For reals (and when I say "man, " I mean "insect") !!

Ahem, so why are there man-eating plants (and when I say "man, " I mean "insect")? Cuz there ain't no other way to get the nutrition, folks. Ain't no way. That soil has very. little. nutrition. Sigh. Here is a carnivorous sundew plant with what looks like insect leftovers.

Sundew you.

And here is the general ecosystem area, preserved courtesy of The Nature Conservancy.

In fact, carnivorous plants thrive best in oligotrophic* soil. In more fertile soil, other plants would outcompete sundews for resources, forcing sundews out. Here are some great links to more info:

The Nature Conservancy's post on the land they conserve.
West Virginia University Extension Service (gotta love Land Grant Extension programs!) gives us natural history of Cranesville Swamp, and why this "southern" ecosystem (compared to Canada, not Texas, y'all) is called an arctic plant community.
Sundew info. This one has pictures.
Awesome brochure.

So if you ever see a man-eating plant in your neighborhood (Run!), it would be rational to infer that you have low nutrient soils! Whoo-hooh!

Why does this area have low-nutrient soil? Maybe another day, because...

An Announcement:

I have a new job!!! And even better, it is at Eastside Memorial High School teaching Math. I'm excited because I might have a chance to provide context to the math through environmental science and engineering (and other ~~more boring~~ equally important academic disciplines)!

It is going to be a busy year, so I will probably only post here to check-in with y'all or post quick links. I'll still be on twitter for bits and pieces and I assume you know how to e-mail me. Of course, I might just be calling some of you and nagging for advice ~~(Jude)~~ in the near future. Until then, hugs you!

Definiciones:

Oligotrophic: low nutrient conditions
Swamp: Forested wetland

In Honor of Soilduck

2011-07-27T13:19:00.000-07:00

In honor and congratulations of SoilDuck's awesome new job (!!!) (What is it again SoiDuck? Where?), I am sharing a few fungi pics. I took them on my vacation to Deep Creek Lake, Maryland, my yearly summer mecca.

SoilDuck really likes fungi. I don't know much about my vacation photo subjects, except that they are decomposers, of course. And that they are located in an area that receives an average of 40-50 inches of rain per year. Compare that ATX's measly-peasly 30-35 inches (No, I'm not mad we're living during an exceptional drought. ~~Yes, I am~~.).

By the way, don't forget that decomposition in general increases with increasing temperature and water. Whooh! On to celebrating SoilDuck...

Looking good in the forest.

Near Muddy Creek Falls at the Park.
Look: moss, fungi and lichen in one pic!
Which is- Plant kingdom (moss), Fungi kingdom, and symbiosis between the two kingdoms (lichen)!

Close-up of emerging 'shroom from the 2nd pic (above).

Close-up of the other one from the 2nd pic (above).

What's this? I don't know.

Forest floor again.

Close-up of it's gills, or lamella.

Congratulations, Professor SoilDuck! Go forth and inspire them with your knowledge and enthusiasm!

"What the...?" Part 2; How to identify a mystery substance.

2011-06-17T11:24:00.000-07:00

Hey guys,
Where did we leave off? Oh yeah, there were two "mysteries of nature" that I was trying to solve:

A yellow flour-like powder veins in the clay; and a
Very thin white crystalline crust on the soil surface.

So I sampled them both.

Freestyle soil sampling.

Here is Mystery #1 in the field. See the yellow powder, look how fine it is. Can you see it spread on my fingers?

Here is Mystery #1 by microscope magnification. I think it is pollen!

They appear circular, but I can't quite tell due to their small size.
I'm gonna try and get some mineral oil magnification soon.

Here is Mystery #2 in the field. To obtain the crystalline crust, I dug out a chunk, which revealed fresh clay (you see the yellow veins, Mystery #1, very clearly). The rest has that thin layer of white crystal crust on it.

Here, I'll "magnify" again, using my special magnifying lens.

Here is Mystery #2 magnified under the microscope and at various angles.

Thank you Eastside Memorial Green Tech and Mr. Moldenhauer for hosting my curiosity!

Here are my future plans (if I can acquire a few supplies with limited effort on my part, ahem):

Mystery #1 (yellow "flour" powder): Access a microscope with greater magnification and hopefully identify the pollen.

You see, each type of pollen looks different when you get up close.

Mystery #2 (tiny white crystalline crust): Attempt to dissolve the crystals in water. Then, add acetone to see if there is any precipitation reactions.

Why? I'm testing to see if it is gypsum. I think it is gypsum because gypsum is a very common white evaporite. Also, the presence of gypsum indicates arid environments (like where I was standing at the time).

UPDATE: I haven't found a higher resolution microscope yet. Also, I tried the acetone experiment, but I don't believe I had enough crystal sample to get significant results; it's a very thin layer. Alas, the mystery continues...

Have a great weekend, everyone!

"What the...?" Part 1

2011-05-05T22:01:00.000-07:00

Once upon a time, I started to write a blog post that went like this:

Recently I went to, according my zero research, the world's largest antique fair(!!!) in Round Top, TX. Fried pickles, fried mushrooms, funnel cake, fresh fried pork rinds, and popcorn may or may not have been devoured ravenously.

We may or may not have found the perfect vintage accessories.

While in town, in a pine forest, I also happened upon a cut in the soil that showed the native clay a few inches below. It had weird yellow veins going through it. The veins were very fine grained, like a flour-fine powder. I dug deeper to see if they thinned out, but after several inches of digging through dry clay, the veins were still there. Can you see them below?

You don't see the yellow veins? Let's try again, with "magnification."

OK?
OK.

"What the...?" I was being SoilDuck's good kind of stupid: stupid yet curious.

Internet research was boring, so I checked in with my fellow twits, to see what they thought. Here were some ideas:

I forgot to mention that there was something else interesting too: a white crystalline crust on the outer surface of the clay.

Here is your first official look at the '"mystery of nature" observed under a stereoscope.

See? It is right there, under the stereoscope.

(Thank you, young scientist, Manuel Lopez for taking this picture.

Thank you Mr. Moldyenhaur for setting up the learning apparatus.

Thank you Eastside Memorial HS for hosting this scientific inquiry.)

Actually, were looking at the white crystalline crust here, not the yellow vein powder. Our computer screen is showing a blurry version of it.

But then I hit a stopping point. I hit Publish anyway. I hope this post finds you well, and if we don't chat sooner, Happy Mother's Day! Thank you to both Granny Sharon and Mother Earth.

Join us next time, in "What the...?" Part 2, How do you identify a mystery substance?

The latest obsession (genus Pogonomyrmex)

2011-04-25T23:43:00.000-07:00

As you read this, you can enjoy the Henry Mancini "dead ant" Pink Panther theme song (1963). Cuz I'm old.

For further evidence that science is everywhere (insert ghosty sounding, "ooooooh!" here), I submit to you, to the best of my knowledge, a red harvester ant nest outside my classroom at Eastside Memorial. Here we are, addressing TEKS outside my window (you know, cuz they are part of the food web). But more importantly, it is fun to engage in my favorite step of the scientific method, Observation, and watch my new favorite Formicidae (ant family) live their lives.

Untitled from TheDirtOnSoil on Vimeo.

Texas A&M, the school my alternate universe self attended, says that by removing the vegetation around their nest, the ants allow the sun to dry out and warm the soil. They dig tunnels and chambers where the workers (wingless females) store seeds, which are their main food source, along with scavenged insects. They'll eat "alfalfa, burr clover, Johnson grass, oats, wheat, Bermuda grass, wild sunflower, mesquite, beans, and others."

That looks like a seed. Food!

Annoyed for the sake of educating us. Thank you, kind Ant.

Hope I didn't squeeze you too hard, but you were trying to get away!

And to quote Texas A&M,

Populations of the horned lizard and the harvester ant, on which it predominantly feeds, have declined in the eastern part of Texas. There are several possible factors contributing to the decline of these species.
Red imported fire ants are believed to eliminate harvester ants and prevent new colonies from forming by preying on mated queen harvester ants.
Red imported fire ants may prey directly on lizards or on hatching eggs of lizards.
Many insecticides used to control or eliminate the red imported fire ant are toxic to the harvester ant, and eliminate the harvester ant more efficiently than they eliminate fire ants. Broadcast applications of fire ant bait products should be avoided in areas where harvester ants are found.
Horned lizards normally inhabit flat, open, dry country with little cover. Urbanization, mowing, shredding, shallow discing and other land use practices can eliminate or reduce the production of weed seeds on which harvester ants feed. Harvester ants and horned lizards, which are dependent upon this ant species, cannot survive in these disturbed habitats.

Mostly, they only bite when harassed, but even when I was indubitably harassing them (see above pics for proof), their tiny mandibles never got a good enough grip to hurt me (and cuz I'm totally tough). So they aren't pests (besides aesthetic issues), AND they are food for our threatened (state-listed) Texas Horned Lizard. If you need more, the enemy of our enemy (Red imported fire ants) is our friend. Yay Harvester ants!

Update: Buried Seeds Turn Into Plants!

2011-04-09T22:10:00.000-07:00

Hello, everyone! Long time no read and write! I've missed you. Lots of things have happened since we last e-spoke, but not much soil-oriented stuff. Let's catch up?

Last year on October 31rst, 2010, many of us celebrated The Halloween. Many of us bought, if not grew, a pumpkin. I bet you even composted it! My readers are so responsible. And then there is yours truly, a different kind of responsible...I thought I'd keep my uncut pumpkin as front door decoration until it started to spoil. Almost 5 months pass by and the loyal little pumpkin, exposed to the ATX elements, gets passed by us every day as we walk through our house entrance. Enter MARCH 2011! The little pumpkin that could, gave up. Ew. Stinky.

Lazy, I contract my son to help me chop up the gooey mess and bury it in place. Cuz, like, the compost bin is ALL THE WAY around my house, IN THE BACKYARD, so far away!!!!

And then...a week later. A little biology reminder.

I feel like I'm at the very beginning of the Neolithic Revolution.

What I find most fun about this li'l situation, is that it is as if the pumpkin knew when to rot- it is the beginning (and almost the end) of pumpkin planting season in Travis County!

In other news, my son thanked me the other day, out of the blue.
I said, "For what?"
"For trees," he said.
I guess he was talking to his other mom (ahem, Mother Nature).

Hello Sandbox, my old friend

2011-03-31T14:40:00.000-07:00

Hello Dear Readers!
How are you today? How is your sun shining? We're having nice, crisp cool weather here. Oh, by the way-

Happy Sandbox Appreciation Day!

Remember that one time (at band camp), when I referred to Sand as boring? Wasn't that ignorant and rude!? With a spirit of atonement and reconciliation, I declare today Sandbox Appreciation Day (I can do this because, who is stopping me?).

Dear Sandbox,

New sandbox courtesy of the very civic Hubs.

You are a pretty cheap way of introducing science and engineering to youngsters of all kinds and abilities (and their reminiscent parents). You are super fun. I remember playing in you for hours and hours under the grateful eye of The Parents (cuz I was quietly and productively occupied without their effort, heh. Love you!).

Hours add up to days and weeks of scientific inquiry. Who knows how long I played in there- my concept of time has evolved.

And now I realize how much I learned from you. Days spent with you, Sandbox, were my first physics lessons.

What did I learn? How to build, in my minds eye, buildings, mountains, rivers, dams, lakes, canals, pits and moats and other natural and man-made wonders. That you have a sweet spot, a preferred soil moisture for forming stable shapes with molds, and reducing your stickiness to the molding buckets.

You subconsciously led my life interest to the earth sciences. You may have led others to NASA. And you are pretty fun. Thank you Sandbox, and thank you Hubs for making one for The Kiddo.

Dear Sandbox,

Big Hugs,

The Dirt on soil

Ask an expert that isn't me

2011-03-02T22:10:00.000-08:00

Ever want an answer to your question from a person, and not The Google? You know, cuz books are so passé? With these links, you can get the personalized soil attention we all crave:

Ask a soil expert from the Professional Soil Scientists Society of Texas, or
Ask a native plant expert from the Lady Bird JohnsonWildflower Center (University of Texas), or
Ask an extension agent, fluent in all types of natural resources from Texas Agrilife Extension (Texas A&M University).

These pages will also find you someone to answer your deep, dark, fertile questions on the world around you. Yay!

What is Science?

2011-01-17T20:24:00.000-08:00

Science isn't being bored in class while someone lectures.
Science is the learning we gain through the scientific method.

Observation Hey, look!
Question Why is it like this?
Hypothesis Well one time, at band camp, this happened, so maybe ...
Prediction it would happen the same way here.
Testing No. Hmm. Wonder why. Let's try this.

And that is all in the way of learning you will get from me today. But you wanna see something cool (Doyle, did you post about this? I forget where I first saw it, but THANKS to who did!)? Look at this.

Wanna read something cool? Read how they did it.

Can you imagine how much sky-watching and tinkering they'd have to do before they'd come up with that system? Quite obviously, for at least a few people, staring out into space (and actually paying attention) was the thing to do. Sweet.

And then there is this:

More outer space, but also really teeny tiny stuff. You must look.

And thanks to Classic Detritus, we get beautiful art, with an explanation of some of it's scientific limitations.

In a nutshell, in "real life," the shell they have in the movie dons't match the math they are showing. It is still a logarithmic spiral though. But I can't confirm, I didn't do the measurements myself.

And of course, there is one of the reasons I wrote this whole post: I found some awesome shells on Galveston Beach on New Year's Day (To my hubs, these shells seemed much more fragile this year than he remembers. Of course, his hands don't count as a scientific instrument. We'd need something with more accuracy and precision. But it got us thinking. What would make them more fragile? What happened between last year and this one? The BP oil spill happened. What was that dispersant again? But maybe these are just older, more worn shells than the ones you've crushed before? No, he says. Well, we know CO2 makes water more acidic. And an increase of CO2 in the atmosphere would influence the dissolved CO2 in the ocean. And acidity "eats away" at calcium carbonate. And if they are made of calcium carbonate...but we don't know. We weren't using the scientific method all the way through, you see? No testing, no researching through peer review journal articles. But observation, paying attention, and wondering and being curious will get you pretty far, but the tedious tinkering of the dedicated and hardworking may save us all.)

You see, science is everywhere. All we have to do is pay attention.

All I got so far in my new room. Don't judge. We can go from here to the scientific method, no probs.

P.S. The way that my tutor groups are divided, I only get the same kids 9 times before my gig is up. I got 9 80-minute sessions to inspire them to consider that Science is the way, the truth, and the life, and that they should never be discouraged from challenging themselves with it's study. No pressure, right? Send advice, now please, thanks.

Bad Mother Earth Daughter

2011-01-12T14:54:00.000-08:00

Ooooh, I've been a bad Mother Earth Daughter! Please Mom, allow me to apologize! But first, let us look at what seems to be the new theme of my blog: illegal yet agronomic art. Let us pause to say

Dearest vandals and/or artists,

I do not support your allegedly illegal acts, oh no! I do however, like your topics of interest. Please pursue them constructively. Mayhaps my Introduction to Environmental Science class at ACC would interest you next semester. You may learn that there are VOCs in them thar spray paints, and there are health risks involved in exposing yourself to them, and then perhaps you would choose to use milk-based paints. Legally. Heh.

Thank you.

Love, TheDirtOnSoil

PS Sorry for the commersh milk link, I'm not getting paid to link to it. But you and Martha Stewart do have something in common!!! And it is a recipe, so- Awesome!

You see? It is hard not to admire the topic.

Back to why I am not on Mother Earth's Good List right now:

The basil seeds will replant themselves, no problem!

I am on a compost break.
My pet soldier flies disappeared (I think I can blame the cold, at least in part. But you know the whole not-giving-them-food thing has got to be causing problems.).
I haven't been prosthelytizing about soil to my full potential: educational blog post frequency = decreasing.
My garden... you know, has been neglected.

Maybe a few minutes of your time, Amanda?

Yet there is hope for me, fellow souls. There is yet hope. For example,

Prosthelytizing will increase next week when I start tutoring science to high school kids and professoring environmental science to college kids.
Also, I did take the Soil Science licensing exam. I didn't say I passed it. That is to be determined.
I've been planning an awesome post *since September cough cough cough* on how urine is chemically transformed to plant food (AKA nitrate) by bacteria. You didn't think it happened all by itself did you? It might be free fertilizer to us, but those nitrosomonas and nitrobacter gotta work for their money. So you know, please keep the faith and stay tuned.

Wait, what is my point? Oh that is right, I didn't have one. Blogging is fun!!

Thank you Parsley, for not making it look so bad. You look great. Keep it up.

Math Science Photo Series

2011-01-09T01:21:00.000-08:00

Found this art on the Speedway Grocery at the corner of Speedway and 38th in ATX. BTW, if you are a very strict parent, don't take your adorable toddler in there because the nice people inside will offer him/her free candy (I guess not everyone is immune to his smile)! But if you are very strict, said toddler will freak out with chocolate glee.

See Roots in their Natural Habitat

2011-01-04T11:51:00.000-08:00

Dearest soil enthusiasts,

¡Feliz año nuevo! ¿Cómo fue su celebración?

To celebrate my new science teaching jobs that I mentioned on Twitter, I'm looking around for fun soil science ideas that address our Texas HS Science learning objectives, TEKS. I found instructions for making a root viewing box where you can make lots of fun experiments. I hope I can muster up the motor skills to make one. Hammer, please avoid my fingers. Thank you. I found instructions here (horizontally oriented) and here (vertically oriented). Mickey over at My Wisconsin Garden made a pretty one with cedar with some nice germination results.

Vertically oriented root viewing box by the NRCS

Of course, we can use root viewing boxes to learn about tropism*, like

positive geotropism (grow towards the source of gravity), and
negative light tropism (grow away form the source of light), and
negative thigmatropism (growing away from obstacles touching them) (activity details for all here)

You could

see how the roots respond to different soil textures (sand, silt, and clay), and
varying soil moisture at depth (water it for longer or shorter time periods)

You could

compare the root lengths of different plants, like native Texan prairie grass to conventional lawn grasses, and then
think about what that means for facilitating erosion (Native is better! But find out for yourself).

You could

do so many things! Heh, you though you were getting more, eh?

Also, the Capital Area Master Naturalist's Education and Outreach Committee has a learning activity on root length, and you can ask them to present it to your group. Any age.

If I make this you'll soooo get pictures, hopefully in a classroom setting, administration-willing.

HUGS.

*Definiciones:
Tropism: A response to stimuli by plants is called a tropism (source).

The Dirt on Enchanted Rock, TX

2010-12-13T11:00:00.000-08:00

An honor to be climbing with The Prez of the Texas Invasive Plant and Pest Council and The Lady that is responsible for my love of science (and wavy hair)

So, me and some lovies went to Enchanted Rock, Texas. It reminded me of my last trip to Enchanted Rock, wayyyy too long ago with a precious godmother, or madrina, who was visiting for a baptism circa the spring equinox. I also have many a memory of camping here during college. Ergo, during this hike, I was twice filled with The Love: the lovies of the present, and the lovies of the past. I will spare you the relevant Sesame Street video, but let's all agree, climbing Enchanted Rock is fun.

What is Enchanted Rock? It is a big granite intrusion. It's most common minerals, I believe, are microcline, plagioclase, quartz, and biotite. You can follow a geological tour up the hill, it's nice.

Schmanyways, obvs there are associated soil photos, but first (!!!) here is what Enchanted Rock looks like from the road.

Since Texas is unfairly known for being quite flat, this is kindof a big deal. Look, a protuberance!

A closer peek...

We climbed to the top and had some cool views.

Forgive me because I have lots of pictures I want to share about an obsession I didn't really know I had: plants appearing to grow out of rocks (!!!).

People in the know are calling them vernal pools. Vernal pool ecology is created by pioneer species: they are the first to colonize a mostly abiotic area.

I like this pic: this is a vernal pool - the first inklings of entisol soil formation.

I think that is an oak tree. Sorry for my photo smidge on the right.

Looking uphill, presumably native grass.

Same area.

Some cactus.

Spatial distribution.

The top.

According to the Texas Parks and Wildlife Department, the plants and animals that live here are "uniquely adapted to a harsh environment."

In fact, by studying weather pits, ecologists learn: (1) how plants and animals colonize a newly formed habitat; (2) how those organisms modify their environment and help develop soils; and, (3) how plant and animal community structure and composition change over time.

In other words, they are super neat.

At Enchanted Rock you can see the progressive development from bare rock-bottom pits, to annual plant establishment, to miniature prairies with grasses like little bluestem and even trees like live oak. Vernal pools also support an interesting species of invertebrate, the fairy shrimp. These tiny animals survive total desiccation as fertilized eggs, and hatch into larvae and grow into adults each time water collects after sufficient rainfall.

Since these things are super cool, and their ecosystems are so fragile, the Texas Parks and Wildlife Department wants to make sure visitors are aware of their significance and asks them to back off.

"STAY ON THE ROCK," they say. And,

"Thank you for protecting an important part of the Enchanted Rock experience."

Look at the length of the root compared to the height of the above-ground portion (green leaves only). This was on the bank of a dry creek bed.

Have a great visit!

P S. Natural resources of Enchanted rock found here.

Six Degrees of Separation: Smectite Style

2010-11-28T00:51:00.000-08:00

Hello, my dearest little poblano peppers!

How are you today? Where are you today? You know, ~~I clicked on something~~ according to my research, there are twelve whole readers of you out there. TWELVE of you that lovingly indulge me with a subscription! I thank our usual suspects, Dr. Doyle, Soilduck, GonferalinID, and Layla. And you others aren't my mom or dad (well, two of you are, but you don't actually subscribe, LOVE YOU!), so... who are you? Please let me know, so instead of me talking about soils I encounter, we can talk about our soils. For example, uno de mis amigos vive en un ultisol importante, y otro vive sobre de roca y un poco suelo (his guest post here).

So please, will you comment and introduce yourself? Or what you want to hear about next? Or a random thought? I'll pause and wait, to give you a moment to do that....

Waiting for you to comment gives me similar existential issues as those confronted by Grover and Telly Monster in "Waiting for ~~Godot~~ Elmo" by Sesame Street's Monsterpiece Theater.

Moving on, I have this little "6 degrees of soil separation" game going on in my head all the time. I believe you can link anything back to soil, just like Kevin Bacon. So today I am going to relate annoying small toads to the chemical structure of smectite*. I know, it's magic! Thank you ;-)

First of all, let us let us focus our attention on a gentle, young, unsuspecting Bufo valliceps toad.

Actually, he indeed suspects, see why below.

According to my ~~research~~ hubs, this toad is a Bufo Valliceps. I like to water my foundation, catch them, and gawk at them adoringly. I pour water onto the side of my house and they all come jumping out from the crack between the foundation and the soil.

You see, when it doesn't rain, my clay shrinks to provide these naifs space to cuddle in a nice, moist resting area.

And when it doesn't rain, I water my foundation to get rid of the very same crack in which they reside (Does it help your foundation stability for reals? No idea).

You see, this toad and my humble abode are located upon a smectite clay. ~~I'm obsessed~~ Perhaps you have heard of this soil here, here and here. Anyways, the crystal pattern for smectite involves adjacent planes, or sheets of oxygen (among other elements). And adjacent oxygens don’t “bond” with each other very strongly compared to say, hydrogen bonding [the polarity of water: discuss]. This means that when precipitation (rain) percolates into the soil, fresh soil water molecules have an opportunity to get all up in between the tetrahedal layers, which pushes the layers apart and increases the soil volume(!!!). Yes dude, the soil gets bigger, and in an annoyingly uneven way. "Le sigh," says my house.

Imagine, the soil under your house is a smectitic, and whenever it rains, the clay under your house expands, and shrinks when it doesn't. It is like building on ... some other slowly flowing (viscous) material. Your walls may crack, your door jams stick. Anyways, we water it in a ~~futile?~~ effort at keeping soil moisture nice and even at all times, which should supposedly preserve our foundation's integrity. And this is where the toads come in again.

In conclusion, our 6 degrees of ~~Kevin Bacon~~ separation:

I pour water onto the soil next to my house foundation so that it will expand to close the crack between the two. Toads hop out of the crack, annoyed (and then I catch them!). You see,
Maintaining near constant soil moisture levels may preserve our foundation located on a smectite clay.
Smectites change volume depending on soil moisture,
Cuz their adjacent tetrahedral layers are only bonded by oxygen bonds and
Water is more electrostatically attracted to the oxygens in between the tetrahedral layers than the oxygens are to each other.
Once hydrated, the smectite clay mineral expands with the added molecules.

Ta da! You too, can use your soil science expertise to mildly inconvenience small animals!

PS These smectitic soils are characterized by high base saturation, partially explained here and here.

Definiciones:

Smectite: A mineral found in great quantities in vertisols, which are known for their shrink swell capacity due to expanding 2:1 lattice clays (source).
Phyllosilicates: Silicates (atomic structures featuring silicon) that combine to form planar sheets.
P.S. They discovered phylosilicates on Mars.

ATX: Your poo promotes birdwatching. Indirectly.

2010-11-04T22:38:00.000-07:00

Birdwatching at Hornsby Bend (Photo credit: Meredith O'Reilly)

Hornsby Bend, Austin’s premier birding location, is a biosolids recycling facility.

Say what? Your beatific contribution to the sewer system via flushing toilet travels through pipes and goes to a wastewater treatment plant. After treatment, the biosolids (or, ~~if you want to sound like a nerd,~~ primary and secondary waste-activated sludges) go to Hornsby Bend, where they are ~~manipulated again~~ ultimately composted with yard trimmings collected from Austinites to make Dillo Dirt (Read page 3 of this doc for more details on how this is done.) The liquid waste portion of the biosolids make outdoor ponds, whose waters irrigate onsite fields.

The birds love Hornsby Bend. They like the ponds, the drying basins, woods and fields:

The biodiversity is present both because of the nutrient rich biosolids treatment processes used by the facility and because of the diversity of habitats at the site stretching along 3 miles of the Colorado River. (source)

We built it, so they came, enjoyed, and returned. And now we can go watch them. Meredith at GreatStems wrote a very nice blog post on Honsby Bend's birdwatching and history.

If you haven’t had a chance to visit Hornsby Bend's neat avian-friendly ecosystem, you should fer reals go.

Here are some visiting tips:

Hornsby Bend Map

Location Descriptions: Where to see What

Seasonal Guide

You can go by your lonesome or join the group activities as listed on The Dirt on Soil's calendar, which include:

A monthly bird survey every 2nd Saturday of the month @ 7am,
Birder led "field trips" every 3rd Saturday of the month, and
Eco-literacy day every 4th Saturday of the month @ 9am -1pm

3 hours of outdoor volunteer work; 1 hour of ecological education

Also, Hornsby Bend is open daily to the public from sunrise to suneset.

The Saaaands are Alive with The Sound of Muuuuusic!

2010-11-04T10:04:00.000-07:00

This post reminds me of that lovely Julie Andrews song, parodied here.

Dear Readers (How are you?),
I confess: I've been pretty biased against sand. Hydrologically speaking (which is totally my paradigm), I consider it the boring soil texture of the three (sand, silt, clay). Por ejemplo:

Water flows through it the easiest (of sand, silt and clay), meaning is has the highest hydraulic conductivity*, and
it holds onto the fewest nutrients because of it's low cation exchange capacity* (I mention CEC here and here).
Also, it's soil moisture curve* leaves much to be desired. I mean look,

(image source, from an awesome looking lecture on soil water relationships in soil)

Just look at how quickly sand loses it's soil moisture when the water table drops (shown on the x-axis). Yawn, right? Clay holds onto it's water!! Jeez.

But recently, I came to terms with the idea that maybe sand was more interesting than I thought. A few weekends ago, we saw some familia in Corpus Christi, TX and went to Padre Island National Seashore (Click here for map). As in, we went to the beach, where you get to play in nothing but pure, boring, bland sand. So you'd think I'd be bored out of my mind there, but lo, it was not true.

Mi familia y yo started digging in the sand of the intertidal zone, and did some learning (BTW, sandcastles, sand-chairs, and drip mountains are totally learning.)

This is South Padre Island National Seashore's intertidal (IT) zone*. The IT zone here would be everything in between the seaweed piles to the low tide waves. An IT ecology lesson here.

Wanna know what we saw? Aliens! Just kidding: one long, skinny worm, tonsa things that looked like dark, stubby worms, a decapod (a ten-footed something-or-other, shrimp?), and something that looked like a "sand crab" to my untrained eye. Kinda like everything on this marine science page (seriously, look at the cool pictures!).

This is a blood worm (genus Euzonus), which might be what I saw (Image credit).

So, in conclusion, the sand is alive! These creatures have ecological importance as nutrient recyclers, just like our soil brethren. For example, can you believe, and I quote:

Some worms called polychaetes [my note: this is a class of worms that inlcude the Euzonus genus] simply eat the sand whole and let their digestive systems clean it off. Out the back end, eventually, comes a trail of clean sand (source).

Blood worms function on the sandy beach much like the earth worms do on land — they ingest the sediments (sand for the blood worms) and digest the organic material found between the sand grains. This type of feeding is called deposit feeding and results in a type of "cleaning" of the sediments. (source)

You mean they poo a trail of clean sand!?!? Awesome. So, why are we thankful for tiny sand creatures? They don't cause diseases and they clean up after our organic mess. HUGS YOU, little sand creatures!!!

And to you, Sand: I'm sorry for thinking you were boring. I love your interstitial fauna* and you are easier to wash off our hands than clay. Thank you, too :-)

***UPDATE***
It turns out that sand is waaaaay more interesting than I thought. Check out this book review blog post by Brian Romans on the book Sand by Michale Wellans. This author also has a SAND BLOG on all things sand! Now back to your regular programming...

*Definiciones:
Intertidal zone: The transitional coastal region located between high and low tide marks (source).
Hydraulic conductivity: "A measure of the capacity for a rock or soil to transmit water; generally has the units of feet/day or cm/sec (source)," or "The ease of movement of water through the soil relative to a potential gradient (source)." Think of a potential gradient as a difference in water table levels: water flows from high to low water table levels.
Cation Exchange Capacity: "a measure of the negative charge on soils (primarily on clays and organic matter). It is expressed as the quantity of cations (positive ions) that can be adsorbed by the soil (source)."
Soil moisture curve: a graph that shows the relationship between soil moisture content and pressure head (aka water table draw-down).
Interstitial fauna (meiofauna): the tiny animals that live in between the sand grains. Also "loosely defined as animals capable of passing through a 0.5-mm mesh (source)"

So, Did You Know That Moss is an Ecological Indicator*?

2010-10-05T12:57:00.000-07:00

I was walking with my chickfriend (not to be confused with chiksa, even though she is one of those too) the other day, and we happened upon what I will call moss (Is it moss? I don't know; I'm a geologist!). It was growing on the sidewalk downtown, under a gutter!

Photo courtesy of my chickfriend Sarah Kerver

For reals, where is your soil, Little Moss? How do you live so bright and happy under a drain spout? On top of cement, apparently very satisfied with the nutrients provided by the accumulation of dust that deposits underneath you?

So it inspired me to look up info on this plant that reminds me of ... my verdant childhood (Maryland has more moss than Texas. Our loss).

So what is moss? Here are some basic factoidals. They are not to be confused with lichens, more on those here. The neat part is, they get many nutrients from rainwater, not soil. However, if the rain droplets are falling through polluted air before they reach the moss (I wish the plural for moss was meece!), it will more likely disturb the moss faster than it will other plants. In fact, moss is a good indicator of air pollution Why? Here is a good quotation from Kevin J. Lyman of the Milkwaukee Public Museum:

Why are mosses and lichens sensitive to air pollution? Since mosses and lichens lack roots, surface absorption of rainfall is the only means of obtaining vital nutrients which are dissolved in rainwater. Lichens and many mosses lack protective surfaces that can selectively block out elements including pollutants that are dissolved in rainwater.

So, it looks like finding happy moss in the middle of downtown ATX is a good sign! Hopefully this does mean that the air around the moss is clean :-)

Wanna grow your own moss? Try reading here first. Enjoy!

*Definiciones:
Ecological indicator: as discussed in another ecological indicator post on a toad, it is a measure of the environment (e.g. the presence/absence of an organism) that is used to evaluate the health of an ecosystem (more technical definition here).

My Morning in Pictures: Soil's Eye View.

2010-09-28T20:15:00.000-07:00

Beet seedlings' eye view.

Driveway's eye view.

My favorite maggots

2010-09-24T15:05:00.000-07:00

The adult soldier fly. Photo credit: Rock Hill high School

Howdy neighbors! How is your soil today!?

I need to tell you about my new favorite pet, the soldier fly larvae. I'm being totally serious. I worry about their health! When I go to my compost tumbler to drop off a new gift, and see hundreds of them chewing on my food scraps, I get so relieved. Yay, they are still there! Phew! Now that I have them, I don't know what I'll do without them. Well, I do- I'll actually have to exert myself and turn my compost instead of just gawking at it lovingly. Don't leave me, maggots! I love how your efficiency enables my laziness!

See them in their gross glory here (click play):

Look at the smiles on those happy Hermetia illucens. That was once an avocado, by the way.

The best part about my maggots is that I pretty much do nothing to keep them around. They are lower maintenance than chickens!! My compost tumbler system is set up well to house them, because I can keep fresh kitchen scraps on the top of my pile, inside the tumbler, and attract the soldier flies without attracting rodents.

Factoids about my new Friends

Heterotrophes*, and detritivores*, these baby solider flies eat rotting things (like my kitchen scraps) like it is their mission in life. They'll take big uncut (read: lazy compost style) chunks of whatever and turn it into homogenous poo so it can further decompose into awesome humus. Ergo, they help me make compost faster. A lot faster. For example, before these guys, we called my tumbler "the preserver" since we wouldn't get but one binful of humus a year. Now I'm depositing pretty-smelling bug poo on my soil that was food just a few weeks prior.
They are voracious and will likely eat scraps before they have a chance to smell badly (even big compost no-nos like dairy, shhhh).
Their poo is a nice smelling soil amendment. Mmmmm bug poo smells like actinomycetes.
The adult soldier flies do not eat. This means that unlike the maligned cockroach and house fly (yuk!), they don't come into your house looking for food! If they are in your house, they are lost; they don't want to be in there! Unless you have rotting food in your house, but that is another discussion (you should clean your house *cough*).
The flies inoculate the compost with beneficial bacteria.
They are native.
They don't bite or carry disease (source)!
They outcompete houseflies for habitat, reducing your housefly population.

Gratuitous macro lense house fly pic: I am not a fan of this diptera (Diptera is the order that characterizes both flies).

Soldier flies have so many interesting positive attributes, that Dr. Watson and others are looking into utilizing them for large scale animal waste management.

Yay!!! Tell me about the bugs in your soil that YOU are grateful for!

*Definiciones:
Autotroph: "The acquisition of metabolic energy from the fixation of inorganic carbon, for example, by photo- or chemosynthesis (source)."
Heterotroph: "An organism that depends on complex organic substances for nutrition (source)."
Detritivore: "An organism that feeds on dead organic debris (source)."

My Friday in Pictures

2010-09-18T20:18:00.000-07:00

Yesterday, I helped at American Youthworks' inaugural "drainage ditch" garden groundbreaking.

An American Youthworks teacher gardens.

Since the gardens are in the drainage ditch, they are watered by rain and from upstream surface and ground water flow. The plants are in raised beds, adding water drainage and preventing their flooding during periods of heavy rain.

This garden is in an urban environment, which has hydrological consequences. As a small scale watershed quality strategy, we made sure to put mulch (e.g. pine needles) on all bare areas.

We weeded and sowed Fall appropriate seeds. The shadow of yours truly is in the bottom left corner.

A look at their compost pile behind the basil.

This is one of my favorite pics from the day. These little garden blessings were placed all around the garden.

I hope you are having a great weekend! Tell me about it in the comments!

The dirt on turning soil into plants: August edition

2010-08-26T13:26:00.000-07:00

OK, you got me:

"A plant's dry matter* consists mostly of carbon, hydrogen, and oxygen, which the plant obtains by photosynthesis from air and water, not from the soil. (Reference #1)"

But the other macronutrients*, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, mostly come from soil solids.

As fascinating as soil is, much of my relationship with it is in the "benign neglect" category. I'm hoping to change that! But it is August and it is hot. What to do in Central Texas?

Texas Agrilife Extension Service gives us a 2010 Travis County Planting Calendar, a list of vegetable varieties, and seed sources. Since today is August 26, the chart says I still have time to plant beans (lima and snap), cucumber, and summer squash. And maybe I could squeeze in some Irish potatoes. So I looked into my seed stash, and here is what I did:

Planted cucumber and bush bean seeds.
Covered them with my low-maintenance, wabi-sabi, I-don't-really-pay-attention-to-it compost.
Watered them lightly. Thought of our abnormally dry conditions. Considered the feasibility of graywater.
Looked around for potato seed resources, and found some awesome potato literature from Agrilife, University of Illinois Extension, and NCSU. Also, Gone Feral in Idaho uses a potato box. Looks easy, maybe I'll try it! Then I realized seed potatoes are hard to find until their spring planting season.

How is your soil today? How are you showing the soil your love?

*Definiciones:

Dry matter: "

the percentage of plant sample, which

remains after all the water, has been removed (Reference: Cooperative Extension Service University of Kentucky and Kentucky State University)."

Macronutrients: "A chemical element necessary in large amounts (usually 50 mg/kg in the plant) for the growth of plants (Reference #1)."

11 things you can do to increase water in Austin creeks

2010-08-26T10:18:00.000-07:00

This creek has high water flow during rain events; you can see the big pile of brush that the water carried. But a day later, it is sunny and the creek is dry (Fort Branch Watershed at Springdale Rd., I think).

We talked earlier about how one of the problems in local Austin streams is that they have too much water when it rains [which renders our poor froggies and fish practically habitat-less from all that turbulence], but not enough the rest of the time. This, in part, is caused by how we have developed impermeable cover on top of our soil. Basically, we've become urban. For more details, please read my post on Watersheds in a nutshell in a nutshell. Thanks! Now onto the proactivity...

There are ways we can help those little froggies and fish keep their homes, and it doesn't have to be done by big groups of people. Each yard can make a difference! All we have to do is point water in a new direction, away from runoff and evaporation, and towards infiltration into the soil and groundwater. When water is supplied to creeks by groundwater recharge instead of runoff, creeks flow at a more constant rate. A more constant flow rate helps preserve aquatic habitat.

Below are some tips directly from the City of Austin's Watershed Protection Department and the EPA that will help our creeks flow.

Structural improvements:

Divert rooftop runoff to vegetated areas rather than pavement (source). This is called rainwater harvesting.
Minimize pavement: use wood decking, bricks or interlocking stones for walkways and driveways (source).
Consider creating grass swales (low areas in the lawn).
Install gravel trenches along driveways or patios.
Make a rain garden- Rain garden instructions
Collect your rainwater to use later - Rainwater harvesting instructions

Plants:

Select yard plants that have low requirements for water.
Preserve existing trees, and plant trees and shrubs.
Irrigate efficiently to avoid runoff from your yard (source). For example, using "slow-watering techniques such as trickle irrigation or soaker hoses reduce runoff and are 20 percent more effective than sprinklers." (Thanks, EPA!)

Ground cover:

Spread mulch on bare ground or restore bare patches in your lawn.
Use compost. Compost retains moisture in the soil and thus helps you conserve water.

Increasing vegetation and ground covers are doubly effective. They increase infiltration, and they also reduce evaporation! Increased evaporation from impermeable ground surface is an often forgotten result of the increased urbanization of our watersheds. By increasing shade, and thereby decreasing heat, we reduce evaporation (click here for more physic-sy evaporation details and terminology, just scroll down on the right side and look for terms). This way, the water stays longer right where we want it, it our watershed!

What about you? Do you have other tips? This is Austin, so we can be creative!

***UPDATE!!!***

Here is a 12th, amazing extra credit thing you can do: Create a green roof! Thanks for the idea, Wildflower Center!

It was hot today: the dirt on the heat index.

2010-08-17T20:47:00.000-07:00

Fer reals. The National Weather Service predicted that it would feel like 110°F (Fahrenheit) today. Same for tomorrow, I hear. This does not bode well for the following polar bear:

Maryland: Where men are almost as tall as mountains.

What are they saying when they predict it will feel like 110°F, even if it is only [only: ha!] 102°F? They are talking about the Heat Index. At first I thought it was the same as the term "effective temperature". Oh, but no; when I looked up that definition, I got this from Columbia University:

The effective temperature of a planet is the temperature it would have if it acted like a black body, absorbing all the incoming radiation received at its surface and reradiating it all back to space.

That's not what I want! This is what I was looking for, from NOAA's National Weather Service:

The Heat Index (HI) or the "Apparent Temperature" is an accurate measure of how hot it really feels when the Relative Humidity (RH) is added to the actual air temperature.

Please click on their link for all the details, it is pretty good text, but in the mean time, here is my favorite part:

The body's blood is circulated closer to the skin's surface, and excess heat drains off into the cooler atmosphere by one or a combination of three ways...
radiation,
convection, and
evaporation.
At lower temperatures, radiation and convection are efficient methods of removing heat. However, once the air temperature reaches 95°F (35°C), heat loss by radiation and convection ceases. It is at this point that heat loss by sweating becomes all-important. But sweating, by itself, does nothing to cool the body, unless the water is removed by evaporation (sweat changing to water vapor). The downside of this method of cooling is that high relative humidity retards evaporation. (reference link)

Considering their explanation, I'm surprised that wind speed isn't factored into it. Doesn't wind promote evaporation? Cuzzzzzz it blows the humidity away?

But here is a funny thing part: the heat index was first introduced by R.G. Steadman (1979) in his document called "The Assessment of Sultriness, Parts 1 and 2."

Sultriness. Hee!

Definitions are funny

2010-08-15T20:02:00.000-07:00

I wanted to talk about the difference between soil and rocks, but when I started looking up definitions, I remembered that there isn't a singular definition on which we all agree for these things. The definition of a word depends on who you talk to, and the definitions bleed into one another.

Geology
For example, I happened upon the knowledge that the classic definition of geology is the study of the earth.

The study.
Of the earth. (Doesn't that kinda mean everything? Doesn't the study of the earth also mean economics and anthropology and religion?)
And its life forms, and the evolution of life.
Which now sounds more like biology.

To be honest, I like this definition. Cuz I think that geology does include the study life and its evolution (for example, paleontology), but only as it has been recorded in the rock record. But what are rocks?

Rock
Please click here for the definition of "rock, " courtesy of the US Geological Survey (USGS). Notice they use the word "mineral." What are those?

Mineral
Please read the definition "mineral," by the Soil Science Society of America (SSSA)- "a naturally occurring homogeneous solid, inorganically formed, with a definite chemical composition and an ordered atomic arrangement."

Oh, but no! The USGS begs to differ. They are more specific than the SSSA's "homogeneous solid," calling it an element or compound instead. I like this better. Also, "the ordered atomic arrangement" is called a "crystal form" by the USGS. Same difference.

I know. Tedious.

Soil
Anyways, here are soil definitions, courtesy of the NRCS.

Here is some mica. Common in the Glenelg silt loam in Maryland. Use fingerprints for scale.

What I get, is that soil has rocks in it, but soil is also an ecosystem. There is air, liquids, and solids in soil. There is water, there are minerals. There is representation from all taxonomic kingdoms of life. Oh and look, there is also my heart and soul (transcendent violins, please! And an angelic chorus).

How to get in on tonight's Perseid meteor shower.

2010-08-11T21:01:00.000-07:00

Did you know that tonight (Texas Standard Time) is the best time to watch the Perseid "shooting stars"? They come around every August. I have some great memories of watching them with many a BFF. So fun. The good news is that, even A-town's night-light pollution won't block out the brightest comets in this meteor shower! Of course, according to Bill Cooke of NASA's Meteoroid Environment Office at the Marshall Space Flight Center, the best show will be away from city lights. "The greater flurry of faint, delicate meteors is visible only from the countryside," he says.

Here is a pic from the same webpage. Imagine lots of these at once [well you know, within an hour]! Weee!

Further details lifted from NASA:

Peak Activity: Aug. 12-13, 2010, approximately 50 meteors per hour. The crescent moon will set early in the evening, allowing for dark skies all the way up until peak viewing just before dawn. Meteor Velocity: 61 kilometers (38 miles) per second.

Note: The Perseid meteor shower is one of the most consistent performers and considered by many as 2010's best shower. The meteors they produce are among the brightest of all meteor showers.

What is the Perseid meteor shower? I lifted this next info from the Discovery magazine blog.

WHAT: The height of the Perseid shower comes every August, because that’s the time our planet passes through a certain debris path.

The Perseids are created by the tiny remnants left behind by comet Swift-Tuttle. The Earth passes through this material once a year, creating a spectacular show as the cometary particles burn up in the atmosphere.

So, in the spirit of pondering that which is greater than us, here is a youtube link.

Vertisols, veritably difficult.

2010-07-28T21:11:00.000-07:00

Once upon a time, I took a class on tropical soil management (SOS 5132) by Dr. Hugh Popenoe, at the University of Florida. Each day, we would get a slide show of pictures from farms all over the world that highlighted low-input agriculture. It wasn't my typical technical science class; we learned from stories. This post is on one of the many cool things I learned.

I got this photo from here

According to the USDA-NRCS, vertisols are high shrink/swell content clays that have deep wide cracks in the dry season. They shrink (to the point of cracking) when drying and swell when absorbing moisture. Also according to the USDA-NRCS, I live on a classic vertisol, the Houston Black Clay (associated sob story and fun fact). The state soil of Texas.

According to my class notes, vertisols typically have a wavy, bumpy surface due to all of their shrinking and swelling. They are usually dark brown, and are located on flat or low slope soils. Although they have a high exchange capacity (ability to hold nutrients), their massive* structure makes it easy to erode.

The shrinking and swelling can damage roots, and the soil is hard to plow unless it has just the right soil moisture (what that magic number is, I can't tell you, it's magic). If you plow it when it is too wet, you will be creating clods that harden as they dry, almost to the strength of rocks.

So how can you manage it? The notes say two things: 1) "Well, annuals, pasture and rice do best on the soil." This makes sense to me since my soil developed with prairie vegetation from a parent material of calcareous clays and marls 2) "You must manage soil moisture, and cultivate at right moisture content."

I have a third tip. If you build a house on it, enjoy the options of either watching grass grow or the cracks on your wall grow**!! They are about the same :-l

By the way, remember my post on the five soil forming factors? Well, vertisols and alfisols (a better drained soil order) are both found in same climactic zone, with the same type parent material, but different topography. They both developed from and found on basic parent materials like andecite, limestone, and basalt.

Links for further study:

Agroclimatology of the Vertisols and vertic soil areas of Africa

Networking on Vertisol management concepts, problems and development

Improved Cropping Systems for the Deep Vertisols of the Indian Semi-arid Tropics

*massive in this case means structureless
** from your house foundation shifting

Plants care about soil pH

2010-07-18T20:07:00.000-07:00

Fact: Soil pH* affects the availability of nutrients for plants.

Here is a figure that shows the relationship of soil pH with nutrient availability to plants. The thicker the color, the greater the availability of that nutrient to the plant. For the most part, plants can get the most nutrition at pH values between 6-7.

Link to image source.

Question: Why?

Answer: Well, one could write a book on this, a looooooong book, but this is a blog post, so let us settle with the main idea...supply and demand!

For the most part, soil has a negative charge. Negative charges attract positive charges (or cations*). Hydrogen has a positive charge...

...and when there is a lot of positively charged hydrogen (i.e., less basic, lower pH), there is more of it available to bind to the negatively charged soil. When more hydrogen is bonded to the soil, there is less of a chance for other positively charged nutrients to bind to the soil. Without binding to the soil, they have a chance to nourish the plant, but they are also more easily leached away (like when it rains).

...and when there is less hydrogen (i.e., more basic, high pH), there is less of it available to bind to the soil. When less hydrogen is bonded to the soil, there is more of a chance for other positively charged nutrients to bind to the soil instead of being allowed to nourish the plant. (Link to reference)

More learning resources:

In case you ever found yourself in front of a classroom of middle schoolers, and all you had were test tubes, plugs, scoops, pipettes, graduated cylinders, universal indicator solution, beakers, three different soil types, a stop watch, a color chart pH scale, and nothing to talk about, I propose this lesson plan for you: Measuring pH in soil. I found this at the University of Texas Environmental Science Institute. It also has other learning resources for teachers and students.

Also, I found a webpage with great links to nutrient management teaching modules. Although they might be easier to read if you have some science background, I am still impressed with their clarity.

*Definiciones:

Soil pH: a measure of the soil’s acidity, or hydrogen (H+) concentration.
pH = -log[H+],
where [H+] = the hydrogen ion concentration.
Because of the negative sign in the definition for pH, low pH soils have more hydrogen than high pH soils.
Acidic soil: a soil with pH values <7 (high hydrogen concentration)
Alkaline soil: a soil with pH >7 (low hydrogen concentration)
Cations: We defined cations here. They are ions that carry a positive charge of electricity.
Cation Exchange Capacity: the total negative charge on soil, which is a good measure of the ability of a soil to retain and supply nutrients to a crop.

Link to image source

As the soil turns.

2010-07-09T18:07:00.000-07:00

Hello dear readers! I went on a quick trip to Swallow Falls State Park in Maryland. Swimming in the waterfall was so much fun! I took a few pictures as I thought about the difference between rocks and soil.

There are 5 factors that work together to form soil:

Parent material - It can be mineral and/or organic (i.e. decomposing plants).
Climate - Different environmental factors (i.e. temperature and precipitation) affect chemical and physical weathering
Living organisms - Among other things, they help organic matter biodegrade, and can mix soil layers/horizons into each other. Their chemical reactions can cause chemical weathering.
Topography - For example, valleys accumulate soil and water, hilltops shed them. This affects the type of soil created.
Time - Neat factoid: sometimes a very chronologically old soil won't be very developed, and vice versa.

For more, there are quick explanations at NASA and the NRCS.

The Soil Science Society of America gives us a two part definition of soil. This is the first part:

"The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants."

Below, I'm sharing with you my pictorial exploration of a plant's contribution to soil development.

Plant pioneers. This guy might trap tiny rock fragments or organic debris which will grow his soil pile. To be honest though, erosion is high here. It was on a slope. This soil might not develop further.

These guys have a small part in a very big process. I imagine their roots will help make this crack a little bigger, making it able to hold even more soil, allowing even bigger plants to grow here in the future.

Growing sideways out of a crack between two rock layers. Not much opportunity for soil development here, but don't tell her!

This shrub (tree?) has chutzpah. It looks like it is growing out of the rock.

It looks like these guys are the furthest along in helping to develop soil, but they still have a looooong way to go! When these plants die, they will contribute organic matter to the soil for new plants.

Even if these little bits of soil are chronological Methuselahs, environmental factors prevent them from developing horizons. Mayhaps erosion rates are faster than the rate of soil development. If so, the soil would be characterized as an Entisol. Entisols are the youngest (meaning least developed) of the 12 soil orders.

And let's end on a lithologic music note...

I am a rock. I am an island!

Humanure and You

2010-06-30T22:44:00.000-07:00

Dear Readers,

My friend is honoring us with a guest post on humanure, and why he does it! We've talked about his soil, or lack thereof, here. I bet he has practical tips for composting humanure effectively and healthfully. Yay!

By the way, to be all official, his post represents his thoughts and feelings, not mine. I offer alternative definitions at the end of his inspiring post.

That is some low soil moisture soil right there.

GUEST POST(!):

My first experience with a composting toilet was 10 years ago in Boone, NC. A friend of mine was living in a yurt on his girlfriend's parent's land. I dreaded using the thing, but I was oddly curious about it. When the time finally came to choose between the toilet and digging a hole in the woods, I opted to try it out. The toilet was right under the deck that made up the yurt's flooring. Literally, right under the kitchen. There was no stink. Not walking up to it, not even when opening the lid.

Looking back on it now, I think it's interesting I almost opted for digging a hole in the woods. There really aren't a lot of differences, a matter of time mainly. In the right circumstances, if you dug a hole out of an old tree stump, it could actually be a single use composting toilet. The main difference is the rate of the breakdown into "humus". Not to be confused with the Greek chickpea dip, humus is what organic matter (ie poop) turns into when it breaks down, but before it becomes soil [Well, I beg to differ. Humus is actually a component of soil]. As it turns out your poop is very useful, nitrogen-rich organic matter. When rendered down to humus it makes a very good and healthy supplement for soil. If animals don't dig it up, a poop in a hole in the woods will eventually break down into humus (and then into soil [same comment here, it is already a part of soil, but I still love you Shindagger]). But a good composting toilet will very quickly turn your poop, which is nasty, stinky and rife with dangerous bacteria, into benign, odorless humus.

Compost, which has become fashionable in recent years, needs nitrogen to be healthy and active. Most compost safe materials are carbon rich, so you really need [a good source of nitrogen such as] the manure from a large animal to keep your compost balanced and working. You can get manure from lots of sources, but don't forget that you are a large omnivore creating nitrogen-rich manure every single day.

I own land in the Chihuahuan Desert, where all my water is brought in by truck, or caught from the sky. The average flush toilet flushes 2-2.5 gallons of water every time you pull the handle. In most cases, they don't use spare grey water caught from sink/bath drains, they use 100% potable drinking water. Once flushed the water is useless, disease infested "black-water". Either it is piped back through a sewage treatment plant, treated with various unbelievably complex techniques and turned back into potable water, or it all goes into a nasty concrete pit in the ground called a "septic tank," where it festers, and leaches slowly back into the ground. There's nothing pretty about a flush toilet. It's an out-of-sight, out-of-mind way to easily deal with your poop, but past all those pipes, mixed with all that water your poop is still poop, and it has to be dealt with. My hero Joseph Jenkins, author of "The Humanure Handbook: A Guide to Composting Human Manure," says "Organic material should be recycled by every person on the planet, and recycling should be as normal and integral to daily life as brushing teeth or bathing." Composting my own poop I'm able to conserve thousand's of gallons of water, which is a precious resource where I live. I feel good about taking responsibility for my own organic bi-product (poop!), and i'm composting it back into safe, usable, and fertile soil. Anyone can do it.

links:

http://www.josephjenkins.com/books_humanure.html

http://weblife.org/humanure/chapter8_2.html

http://www.howtocompost.org/

Sincerely,

Creosote Composter

Thank you, Shindagger!
He sent me a funny picture with his post, but I just couldn't put it on my main page, because it has a "bad" word on it, albeit in another language (Spanish). So, knowing this, if you are ready to see his toilet's anti-theft system, have at it.

*Definiciones:

Humus: "That more or less stable fraction of the soil organic matter remaining after the major portions of added plant and animal residues have decomposed (refrence #1)."

Watersheds in a nutshell in a nutshell

2010-06-15T23:31:00.000-07:00

Hello! I would like to describe to you the issues that are paramount to my watershed in such a way that you learn about watershed management principles. First of all, what is a watershed?

A watershed is a piece of land that drains water to an outlet. An outlet could be a river mouth or an aquifer*. There is no scale requirement for the definition, and there can be watersheds within watersheds. They can be super-big or tiny. For example, the Fort Branch watershed is neighborhood-sized and is a subwatershed of the Austin watershed (city-sized), which is a subwatershed of the Colorado River Basin (about Texas-sized). Live in the U.S.? You can find your watershed here (go to the water section and click "Hydrologic Units," then on "Redraw map") and here (scroll over the names to see the watersheds light up). But technically, you can make a watershed while building your sand castle.

OK, so technically this isn't a watershed since it isn't "land," but close enough. Look, there is an outlet!

So, the watershed, like all things, participates in the hydrologic cycle. As in, when it rains on the land (and you inhale the sweet scent of actinomycetes) some water…

Infiltrates into the soil and is either stored in place or percolates further down to the water table; or
Becomes overland flow, runs off, and maybe ends up in a river down the hill; or
Transpires. "Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves (reference)." Some water
Evaporates up from the land to the clouds again. Evaporation is "the process by which water changes from a liquid to a gas or vapor (reference)."

There are other parts of the water cycle not mentioned here, like water storage in glaciers. Want more details? Click here.

Here is a picture courtesy of the USGS that helps the visual learners.

Thanks, USGS.

So, what is going on with the hydrologic cycle in my watershed? Well, there are some complaints. If you read this report, you’ll see that aquatic habitat in the creek has been rated very poorly. Why? Well, if aquatic habitat isn’t even in the creek (for the most part), you can’t rate that category very highly, can you? And what does aquatic wildlife need, but …water (aquatic, water - you see where I am going with this)? There isn’t enough water in our creek to support aquatic habitat. Now, the cynics out there might ask, well… so? Is not having aquatic wildlife bad? Well, I guess it is up to us to decide. But let’s discuss why there is not that much water in our creek, and then we can decide what to do about it.

Here we are upstream, a day after a big rain.

Remember, oh so long ago, when we discussed how rainwater either soaks into the ground or runs off, down slope? OK, well when you cover up your watershed with impermeable stuff like cement and asphalt, the rain is more likely to runoff. Since it will drain off all at once instead of soaking in, the river draining this watershed gets a lot more water at one time. So with the same amount of rain, the water flowing in a river that drains a "pavement watershed' will be high all at once, and then a lot lower later on (drip, drip). A watershed covered in permeable stuff like soil will contribute water to the river flow much more slowly, so the river flow would be more constant. River water flow in a "soil watershed" wouldn't reach the high peak it reaches for a “pavement watershed.”

So maybe, we don’t have so much aquatic habitat or wildlife because our watershed is partially covered in pavement, which is preventing the soil from absorbing rainwater and helping to keep the river flow at a more constant level. Gasp!!! There is SO much more to talk about, so stay tuned! Coming up we'll learn why the Austin watershed experts don't want clean rocks in their creeks (?).

*Definiciones:

Aquifer: a water-bearing rock that readily transmits water to wells and springs (which can form rivers) (U.S. Geological Survey, 2010).

Water budget: the study of the water that goes into a watershed versus what water leaves the watershed. It is assumed that the water budget of my watershed has changed due to patterns in development.

This might be a Bufo valliceps

2010-06-10T22:24:00.000-07:00

Y'all, I went on a super-fun creek walk today with employees of the City of Austin's Watershed Protection Department. When I arrived at our meeting place (Fort Branch Creek at Glen Crest), I caught a glimpse of breeding season in action. Bufo valliceps (photo ID'd by my herpetologist hubs)!! Although I wish this toad was a good ecological indicator*, these guys are quite common and can live within a broad range of environmental quality. Here they are, celebrating life, in their own way.

Who you callin' a Bufo valliceps? I'm a Gulf Coast Toad!

See all that stuff that looks like black strings? Those are their baby babies (a.k.a. [hopefully]fertilized eggs)! Here is an underwater view.

Photo credit: Staryn J Wagner. Environmental Scientist, City of Austin, WPD

Aaaaand, lucky me, I got to hold the gooey lovies in my hand.

Photo credit: Staryn J Wagner. Environmental Scientist, City of Austin, WPD

Here is what they sound like (#151)!!

What does this have to do with soil? Our activities on soil and how we manage it influences the Bufo valliceps habitat. How!?!? Come back next time for answers ;-) Hint: it has to do with stormwater runoff, rainwater percolation, peak flow and velocity.

*Definiciones:
Ecological indicator: a measure of the environment (e.g. the presence/absence of an organism) that is used to evaluate the health of an ecosystem (more technical definition here).

Who is eating my chicken poo? Staphylinidae!

2010-06-08T12:49:00.000-07:00

I always thought that my chicken ~~poo~~ manure disappeared quickly because bacteria really appreciated its great C:N ratio. Chicken manure is very high in nitrogen (Hurrah! [if managed properly]). However, I noticed that there are teeny tiny insects that seem to be eating it, pelletizing it, and keeping my dirt in aesthetic order. So, it's time to thank some of our less glamorous brethren in the web of life, insect decomposers!

But what is this particular beetle? Can you guess? Here are some pics:

Here is another.

Oh, and you need a scale, so this picture shows the lines of my notebook paper. So here is your scale. Kinda. I measured them later and they look like they are between 1/8 - 1/4 inches.

And finally, here they are dancing the day away...or eating a most unappetizing lunch, in the mind of this humble heterotroph.

Helpful moving bugs of mystery from TheDirtOnSoil on Vimeo.

A friend of a friend, entomologist Josh Bast, says this bug belongs to the Staphylinidae family, common name Rove Beetle. Now, staphylinidae is a huge family, that includes over 54,000 species, so I'm still not sure exactly who these helpful guys are. However, the University of Florida's Entomology & Nematology Department web page has a few facts about the large family:

Most fold their wings up very tightly beneath very small elytra*. They are so small that they almost look like part of the thorax* (via Josh Bast).
Although none are truly aquatic, they occupy almost all moist environments throughout the world: under leaf litter, inside mushrooms(!), decaying trees, burrows, caves... seashores.
Many help reduce populations of insect pests such as mites, biting flies, mosquitoes, and fleas.
Their presence in carrion can help forensic entomologists.
With one exception (Paederus and its close kinfolk), they are not pests. But even Paederus have redeeming qualities. Yes, touching Paederus beetles may cause us dermatitis, but their toxin pederin is used for its therapeutic effects. AND some Paederus species are valuable predators of crop pests.
Finally, Staphylinidae form a substantial part of the world's biodiversity.(source link)

*Definiciones:
Elytra: The hard outer wings of a beetle or other insect. Elytra help protect the insect.
Thorax: The middle section of an insect's body. The legs and wings attach here.
Definitions courtesy of Fairfax County Public Schools.

P.S. Ooh look: a lesson plan on decomposition!

Preparing for "Mi watershed es tu watershed."

2010-06-04T11:44:00.000-07:00

I'm preparing for a post on the Forth Branch Watershed in ATX and general watershed management principles. I'm hoping to meet up with an Austin Watershed expert, Mateo Scoggins. Do you guys have any questions you'd like to me to ask him?

Here is what I will ask him:

What influence does Reagan High School have on the water quality of the Fort Branch watershed?
Do different creek segments have different environmental issues (upstream vs. downstream)?
What can citizens do to help?

And finally,

Why was the creek black during that rainstorm? My guess? Tar from the roadside.

In the meantime, please have fun with this watershed-related activity. Make some seed balls. Planting native plants along creek beds (like the wildflowers in the seed balls) help prevent invasive species from settling here. Want free seeds? Apply within.

Image credit: Wildflower.org

AND (!)...TxDOT says wildflowers help improve water quality! See?

Helping the environment was never so pretty.

Here are some definitions for you to look up as homework. Hee.

watershed

infiltration

non-point source pollution

point source pollution

Those actinomycetes sure do smell good.

2010-05-26T12:46:00.000-07:00

Here in ATX, it rained the other day. And boy-oh-boy did it smell wonderfully refreshing. It reminded me of a much-maligned kingdom (or domain, depending one what taxonomic ranking system you use): bacteria! Although bacteria can get a bad rap, we can thank them (particularly the actinomycetes) for one reason behind that fresh rain smell.

Here are some potential causes of our odoriferous joy:

ozone from a thunderstorm,
petrichor (click here to read multitudinous gargantuan technical words), and
geosmin, which is produced by the Streptomyces bacteria, a genus within the group actinomycetes!

Factoid: It is a type of terpene (we've discussed terpenes before).
Factoid: It can give fish an unpalatable flavor.
AWESOME factoid: Wild Bactrian camels may be able to smell water up to 50 miles away because they can smell geosmin. Thank you soil bacteria for helping the thirsty camels!!

Do you learn by listening? Listen here for an easy to understand explanation, covering the same stuff mentioned above.

Besides that wonderful smell, there are other reasons why actinomycetes are awesome. I imagine you've heard that bacteria such as rhizobium help legumes obtain nitrogen from the air. Well, the actinomycetes genus Frankia helps non-legumes fix nitrogen from the air. This means that they can help plants colonize infertile and newly forming soils. Also, many actinomycetes can digest what others can't. Those hard to decompose substrates such as chitin and cellulose are prime picking for these guys. That is great news for compost with sawdust and branches!

Want more actinomycetes? They can tolerate arid and salt-affected soils. They work best in soils with a pH between 6.0 - 7.5, but are more sensitive to acidic soils. Don't worry too much about acidity though, since fungi can take over the decay where actinomycetes leave off (info also from reference #1).

Also, this great article says that daily turning of compost, while good for some purposes, can inhibit growth of actinomycetes. Although actinomycetes can either be mesophilic* or thermophilic*, they are mostly known to work in the later, cooler stages of compost creation. If you see something that looks like gray spider webs in the outer edges of your compost, it just might be actinomycetes. Please remember to say, "thank you!"

Please enjoy your "rain smell" responsibly.

*Definiciones:

Mesophilic: microbes that function at temperatures above 113 °F

Thermophilic: microbes that function at temperatures between 50-113 °F (10-45 °C) (ref)

Basic soil physics lesson plan up and running

2010-05-17T12:18:00.000-07:00

Hey guys,
I'd like share a lesson plan with you that I wrote for school-aged kids. I don't see a way to post a PDF on blogspot, so I put it up here instead. It is about one of my favorite soil topics- soil porosity and water storage! After you read it, you can consider yourself better versed in basic soil physics!

Thoughts on the lesson plan? I'm thinking of writing up more, in hopes that I can put them to use in "real life" one day.
Thanks!
Amanda

UPDATE! This USGS link is awesome and also teaches us about capillary action.

An even smaller snake?

2010-05-16T00:13:00.000-07:00

I had no idea they would just get smaller. Yes, you are using my fingerprints for scale!!

That, according to ~~my hubsy~~ a bona fide herpetologist, is a Texas Blind Snake (Leptotyphlops dulcis). Another fossorial snake, a burrower. According to Bastiaan M. Drees of Texas A&M, this little guy indicates a healthy environment. Quoting him, they eat "larvae and pupae of insects, termites, and earthworms."

In a way, he/she reminds us how intimately we depend on soil. For example, their residence in the soil seems to be partly determined by soil moisture. They like it, but of course sometimes it floods them out. This page says that they move deeper underground when the surface soil dries out in the summer, and this page says that they are spotted more easily after a rain (like today, what a coincidence). I imagine it's cuz their burrows got plugged with el agua. Soil moisture reminds me of a lesson plan that I want to share with y'all, but I don't know how to put PDFs on here....

Anyways, they are nice guys. They stay small, don't bite the homo sapiens, and they eat garden pests. Let's keep him!

If you want to read about the more gruesome aspects of their hunting style, and reads words like "chemoreception," click here.

Are y'all encountering some awesome soil creatures as well?

This snake

2010-05-10T09:40:00.000-07:00

This snake came out to play as we were ripping up some invasive jasmine for a new chicken play yard. He and his cousins were out en masse! He is a rough earth snake (Virginia striatula), a native in this area, and he eats earthworms almost exclusively.

At first I was sad to learn that this guy eats one of our most beloved and useful soil friends. Earthworms are what we call a keystone species, because they are almost exclusively responsible for their function in the soil- creating aeration macropores. Macropores are an important part of healthy soil structure (more here and here). But then I turned that frown upside down when I realized the implications. We must have a TON of earthworms if their population is sustaining a huge number of rough earth snakes. Yay!

Rough earth snake facts (from here):

They are fossorial (live underground), and viviparous (give birth to live leetle baby snakey-poos).

More worms facts:

There are over 7,000 different species of earthworms around the world.
They like soil with lot of calcium for their slime production (we've got that here, my soil was formed from calcareous clays and marls), and moist, well aerated soil with ground cover (like that invasive jasmine we just killed,oops).
They are sensitive to salinity, sandy soils, ammonia fertilizers, carbomate insecticides (and others), and sudden heavy frosts on unprotected (unmulched or otherwise covered) soils. Tillage is the WORST for them, and their population will suffer dramatically from this.
This web page is awesome for kids and adults. The lesson talks about how worms can adapt to different soils and temperatures. Also, it tells us that some of our U.S. worms may not be native! They probably came over from Europe, along with their fellow homo sapien immigrants.

Biodiversity factoids:

Many scientists believe that there are more species below our feet than above them.
Forested soils generally house a larger diversity of soil animals (fauna) and more fungal-dominated microflora than grasslands, but
grasslands support greater soil faunal mass per unit area with higher activity (measured as more CO2 generated through respiration) than forested areas.
Tilling reduces habitat for soil animals, and cultivated fields have fewer soil organisms and lower soil organism biomass.

(Worms and biodiversity facts from reference #1)

The Skinny on Pine Needles

2010-05-06T09:50:00.000-07:00

Pine needles were recently thrust into my consciousness by two friends. So, if you don't mind, let's discuss the skinny on pine needles, shall we?

But before we delve, side note! I did learn one consideration in its sustainability of use during my internet perusing. Harvesting pine needles off the ground, like harvesting any other crop, ultimately reduces the nutrients in the soil, so conscientious pine needle collectors may want to give something back for the taking.

Moving on, did you know how awesome they are? They are a pretty good mulch! Look at all these reasons! Particularly on hillsides, since they interconnect with each other and stay put. But many people believe that pine needles, as mulch, add acidity. Perhaps they read this link (look under wheat straw). But what if you didn't think it was acidic at all, because you read this link? Or what if you were like, who cares, I read this pine needle apologist! So I asked the expert who wrote this, where he originally writes that pine needles should be put on acid-loving plants. He is Dr. Don Rakow, Executive director of Cornell Plantations at Cornell. He explained his text succinctly:

Pine needles have been shown to be slightly acidic, usually in the range of pH 6.0 – 6.5. This is not very different from average rainfall pH. The acidity is related to the presence of hydrogen ions in the volatile terpenes in the needles. For a review of a somewhat rigorous series of experiments that examined this subject, check out: Pine Straw (Pine Needle) Mulch Acidity: Separating Fact From Fiction Through Analytical Testing by Scott Jacobs.

So there you have it, it is acidic, but only temporarily and not enough to worry about. So all the supposedly conflicting information from reliable sources out there, were all right in their own way. So I guess this is another YES WE CAN, agree moment, heee.

By the way, you may be curious about terpenes. They are "compounds produced by plants from isoprene, a hydrocarbon that has its five carbon atoms arranged in a branched chain." They smell really good, and in the leaves of a conifer tree suffering from air pollution, they change in chemical composition and amount (more evocative terpene-talk here, from where I got this info). Wow.

Pine needles by any other name would still smell like terpenes.

(P.S. One day I'll read the instruction manual on my camera, and maybe get a better pic for you)
(P.P.S. Speaking of soil myths and mulch, here are some interesting tidbits on mulch selection from an Australian soil blogger)

Something we can all agree on...COMPOST

2010-04-20T20:42:00.000-07:00

Yes we can, agree.

Great pontification, dear ~~readers~~ reader! Decomposable compost is great for the soil, beyond just soil structure improvements. It does more than provide food for the soil microorganisms that help aid in aggregating soil. Let us draw our attention to the mother of all soil amendments (please think out loud in a bellowing voice), Compost!

It increases cation exchange capacity,
improves structure,
helps retain moisture,
and provides nutrients!
It can almost do no wrong!

As an aside, you can use manure to make your garden compost. I am trying to help a friend learn about the nutrient profile of elephant and donkey ~~poop~~ manure for her bipartisan victory garden. Ideas on where to find that info?

Here are some interesting links I found during my, so far unfruitful, search.

Land application of Animal Manure by Clemson University Extension;
Considerations in Using Livestock Manure as Fertilizer by Alabama Cooperative Extension System; and
Using Dog & Cat Manure on Home Gardens (hint, probably not the best idea) by University of Minnesota Extension Service.

What do bees have to do with soil?

2010-04-20T10:47:00.000-07:00

What is a picture of a flower doing on a soil blog? I'll tell you! I'm hoping that by letting my collard greens flower out, and get taller and taller and taller, that the roots will get deeper and deeper and deeper. I'm hoping that these roots will help improve the sad soil structure of my villainous vertisol. Now, I didn't ask a real soil scientist if this would work. I'm just guessing based on what I've read here (Reference #1). So why do I think this will help my plants down the line? Let's read bullet points!

Soil texture* and soil structure* determine the ability for a soil to hold and conduct the air and water that plants and soil animals need.
Vertisols (high clay) are known to be massive* under wet conditions.
My clayey soil, with no structure (massive), might not have enough structure to allow proper drainage and aeration.
One step in getting good structure is getting some good macropores* going. They will allow space for roots to grow and to allow for flow of water and air.
Macropores can be made by roots and other living organisms, they are called biopores.
Other things help structure too:

Minimizing tillage,
timing your soil traffic on drier days (don't crush those precious soil peds),
mulching,
adding organic matter to promote microbial decomposition,
using cover crops or rotating crops which promote root growth, and
adding gypsum or other soil conditioners (works best in irrigated soils).

I wish you the best of luck with your soil structure!

*Definiciones*:

Soil texture: the relative proportions soil particle sizes (e.g. sand, silt, and clay)

Soil structure: the arrangement of soil particles into larger units, or peds. Link to examples

massive: No visible structure, or aggregation of soil particles.

macropores: Soil pores large enough to allow water to drain readily by gravity. They generally have a diameter larger than 6 mm. You can consider this useful void space.

biopores: Large soil pores that were made by roots, earthworms or another soil organism.

What are cations, why do I care.

2010-04-07T20:24:00.000-07:00

Soil is so interesting, it makes me want to stare into space.

What are cations?
They are ions that carry a positive charge of electricity (Reference 4). The common soil cations are calcium (Ca+2), potassium (K+), magnesium (Mg+2), sodium (Na+), and hydrogen (H+) (What is an ion, you ask. An atom or molecule that has lost or gained a charge -by losing or gaining an electron).
Why do we care?
Many of these cations are nutrients for plants. Different soils have a different capability to hold these nutrients (and other non-nutrients e.g. aluminum Al+3) and store them. This is quantified by cation exchange capacity. The higher the exchange capacity, the less likely your favored cations will leach away from your beloved plant roots (and in tangential news, the lower your "base saturation", the less likely the mineral will give that cation up and let it go into the soil water solution for roots. What is base saturation? I'll get back to you with an eloquent reminder, just... remind me).

The Joys and Turmoils of the Yard Bird

2010-04-05T19:13:00.000-07:00

Chickens provide many benefits and obstacles to the garden. Here are some examples-

Their healthier, yellower yolks from eating greens (&bugs?) in your garden (omega-3s & carotenoids, etcetera, baby!), but be careful they don't compete for foods you intend for yourself!
They make high nitrogen (nutrient) compost, but be careful it is "aged" properly or it will burn your plants or contribute disease to the soil. Spreading it thin by always providing them fresh yard prevents some issues.
They are good surface tillers, and their "tilling" is less likely to hurt your soil structure; but they are SO good, given the chance, they'll get everything;
Pest eradicators. They are equal opportunity hunters, so they will assassinate garden friends and foes- be careful!

"What is your soil?" is the new "What is your sign?"

2010-03-27T23:49:00.000-07:00

Vertisol at the playground. 8-foot baby used for scale. See the shrink/swell cracks?

I'm a Taurus, and I love asking people this question. But more and more, instead of looking at the stars, I'm going to look you up via the ab-fab NRCS Web Soil Survey (WSS) to see what kind of soil you have.

For example, I proudly (and digruntled-ly, given its issues with construction and amateur gardening) live on the state soil of Texas, the Houston Black clay, a Fine, montmorillonitic, thermic Udic Haplustert. The "ert" in Haplustert means it is a vertisol- a shrink-swell clay (we've discussed the joys of this before).

Ultisol Analysis!
Anyways, my friend and fellow soil-o-phile over at the Bipartisan Victory Garden lives in Florida, and on the (drum roll please) Millhopper-Urban land complex, 0 to 5 percent slopes! Ooooooh! What does this mean for her? Let us consult the WSS, shall we?

This series is a Loamy, siliceous, semiactive, hyperthermic Grossarenic Paleudult. The "ults" in Paleudults means it belongs in the soil order Ultisol. Booooohhhhh. Very sad. Why? Ultisols are naturally low-nutrient soils. Not only are there not many nutrients, it has a low cation exchange capacity (!), which means even if you add nutrients, the soil will have a hard time storing them. However, there is a lot of good news. Especially considering the woman on this soil- she can pay attention, and this soil responds well to good management. Here is the good news-

these soils are formed in areas with long growing seasons and plenty of water (this is where the "ud" in Paleudult comes from: humidity),
the silicate clays in ultisols are usually not sticky (unlike my lovely smectite vertisol, sigh), meaning they are pretty workable,
with lime (to counteract the soil's acidity) and proper fertilization (and compost, mayhaps?), this soil competes with the breadbasket mollisols and alfisols we all pine after ;-) HOWEVER, liming an ultisol to >6.5 pH can reduce phosphorus and micronutrient availability. Why? Not sure yet. It has something to do with precipitation of Ca or Mg phosphates.

Más definiciones:
Hyperthermic: >22 degrees Celsius average annual temperature
Thermic: 15-22 degrees Celsius average annual temperature
Ultisol: soils with low base saturation (<35%) and an argillic or kandic horizon (translocated silicate clay) or fragipan. Base saturation decreases with depth (reference).
Vertisol: Soil with 30% or more clay and that shrinks when dry (and cracks) and swells when wet.

Why you need enough Nitrogen in your compost

2010-03-26T10:49:00.000-07:00

This bird bath needs compost.

A major source of locally derived soluble nitrogen (N) for your plants is...the bacteria that eat your compost! They live at a certain ratio of C:N (carbon to nitrogen). Since there is usully enough C in the environment, these guys are usually hunting for N. And if they can't find enough N in the environment around them (say, your compost bin), then they can't grow. So if your compost does not have enough N (too much C) , it won't break down very quickly. But here is where your garden comes in- if you put fresh compost onto your soil that hasn't completely broken down, and there is not enough N in the compost for the bacteria to grow, then the bacteria will compete with your plants for the N in the soil water solution- no bueno!

Sources of nitrogen for your compost:

coffee grounds (just like manure, don't add directly to plants before composting!)
animal manure (make sure this cures, there could be disease)
any more ideas?

This looks like a good place to add some Nitrogen!

If you don't have coffee grounds or animal manure, don't worry. Most mature household compost has plenty of nitrogen (a ratio of 15:1 versus the maximum 25:1 ratio). Just make sure you don't input too much "dry" stuff to your compost, such as dried up grass or leaves. For example, sawdust, straw, and newspaper has WAY too much carbon to compost on its own.

Compost teaser

2010-03-12T21:11:00.000-08:00

Indeed, my compost smells like roses.

A commenter recently asked how to get started on compost. I haven't gathered all the necessary information yet, but I wanted to give you a quick factoid to get you interested. The time that it takes to transform your compost into usable nutrients for your plants can vary from days to years, depending on environmental conditions and contents of your compost. The fastest way to get nutritive use from your compost (there are other uses!) is to create the following conditions:

temperatures between 77 and 95 degrees Fahrenheit (25-35 degrees Celsius),
a pH close to neutral,
good soil moisture(within your volume of soil, about 60% of the void space is filled with water instead of air), AND
good aeration (reference).

Gardening on the Limestone rock land-Lozier association

2010-03-05T20:17:00.000-08:00

A friend of mine lives on this soil association. What type of soil is this? It is pretty much just solid rock! My favorite quotation about this soil, from the archived El Paso County soil survey is this:

These very shallow soils have a surface layer of pinkish-gray, calcareous, moderately alkaline stony loam that is about 5 inches thick over limestone. All of this association is used as rangeland or for wildlife or recreation. Hueco Tanks Park, a recreational and historic site, is on the association.

I can't find the soil genetic line right now (a.k.a. it's proper name starting at the order level)

My first thoughts: There is no soil to garden here. Anyone trying to improve the soil for gardening is in it for the long-term ;-) So to grow any non-native plants, you'd essentially be container gardening. Bring in yer soil; maintain moisture content with compost/organic matter; strategic water supply; protect with shade; use that humanure you bragged about.

What will your humanure do to this soil if incorporated long-term? Will its acidity help breakdown that limestone rock? Hmmm....

Any other suggestions, other than head on over to the grocery store?

Why you wait to walk on wet soil

2010-02-27T00:01:00.000-08:00

Our gardens love the rain! But be careful, wet soil is more vulnerable to compaction, especially clayey soils. The physical damage from compaction can

increase bulk density, where soil pores are now too small to accommodate the root cap's growth
increase soil's ability to resist deformation (soil strength), and prevent root penetration.
crushes natural soil aggregates and associated macropores, thereby preventing adequate water and air flow.

All this means reduced root growth and therefore less overall vigor of a plant, from your garden plants to large trees! Clay soils are more vulnerable to having their structure damaged due to their increased plasticity and cohesion. Try not to walk too much on your wet soils; perhaps make a permanent path in your garden to help you remember.

Here are some definitions:

Bulk density: weight per volume of soil
Soil Strength: ability of a soil to resist deformation (change in shape)
Plasticity: ability of a soil to be molded or deformed by pressure
Cohesion: stick/stay together
Soil aggregates: soil particles that are held together in one mass
Macropores: soil pores large enough to allow for air and water flow, and even some small animals (some animals make macropores!)
(reference)

Enjoying the Archived PDF County Soil Survey

2010-02-21T19:50:00.001-08:00

If you are someone who likes to read paper more than a screen, you may consider using the Archived PDFs of the County Soil Surveys instead of the online web soil survey.

From the archived Travis County survey, I found out that the soil under our house is part of the Blackland Prairie Texas ecosystem. We live on the Houston Black series, which is the state soil of Texas. Its usefulness in crop production is mentioned, and it also warns that its shrink-swell capabilities ... well, let me just quote it.

"The main limitations in use of the soils of this association in urbanization are the shrink-swell characteristics, as they affect foundations and streets; corrosivity, as it affects pipelines and cables; and the poor suitability of the soils for septic systems."

Our whole street is on this soil, and many of us are having foundation issues, and pipeline issues. The corrosivity that the survey mentions is showing up on our own rusted pipes.

Why is it corrosive? Is it more than just the high water holding capacity? Interesting...

Anyways, if there is anything for which you'd like to use your soil, you'll find it here in these soil surveys. Awesome!

When clay soil and cast iron pipes meet

2010-02-15T10:45:00.000-08:00

My house is among the many houses built in East Austin in the late 1950s (and maybe other places) that used a unique type of iron pipes for the sewer pipes leading from the house to the city sewer mains in the street. Typically houses are built with cast iron pipes, but this iron was centrifugally spun to create the hole in the center instead of in a cast (info courtesy of our plumber). Somehow this makes them more vulnerable (not sure of the details). Anyways, over time, the chemicals we pour down our drain can damage any iron pipes. Also, in the case of our house, if you don't have enough slope in your pipes, standing water can them rust away. It is possible that over time, corrosion of your pipes will accumulate such that you get a hole in your pipe, and instead of waste water being delivered to your city sewer system, you are also watering the ground underneath your house with chemicals (shampoo, household cleaners etc.) and other gross human goo. Another reason these pipes may be seeing their last days is that they reside in clay soil. Clay soil retains water very well, and we all know what happens when you mix water and iron: rust! Anyways, it is 2010 and this is a picture of the pipes that are now being excavated from our soil not a moment too soon.

Find out more about the soil under your feet; NRCS Web Soil Survey

2010-02-15T10:00:00.000-08:00

Have you ever wondered about the soil under your feet, or somewhere else specific within the US? The USDA NRCS Web Soil Survey can answer SO MANY of the questions you may have about the soil of a small (10,000 acres or smaller) area. Learn things like the following:

Native vegetation most adapted for the soil
Recommended uses and limitations (e.g.:agriculture, building, recreation)
Potential hazards (e.g.: prone to flooding, easily eroded, low fertility)
Chemical and physical characteristics
Name of the soil

It is quite easy to use and there are instructions on the home web page. Basically, this info is pretty much taken from the most recent county soil surveys, which have been written for almost all of the counties in the US and describes the types of info listed above. You can type in your address or graphically select the area you are interested in, instead of going the old-fashioned way and reading a map yourself. Reading the archived county soil surveys is easier for me when I am trying to learn about multiple soils within a larger area. You can also make pretty reports with some of the the same information using the Soil Data Mart.

Image found here: http://soils.usda.gov/technical/soil_orders/