Red soil

[MattyB]

I was browsing around on palmpedia and noticed this picture and how red the soil is.  The soil around my place has a slight red tinge to it also and I've noticed several hills around San Diego County that have this soil coloration.  What's this from?  Is it iron oxide that's rusting?  Is this beneficial to plants, ie. like ironite?  Let's talk.

P.S., my dogs find little chunks of Decomposed Granite and crumbly rock and love to eat it and crunch on it.  What's up with that?  Metallic Taste? (that's the name of my new band by the way)

[freekypalmguy]

I think you nailed it. I was just up in Bryce Canyon this summer and that was the explanation given. Rusted iron in the soil. It sure looks cool.

[Tad]

just a little south and to the west in Mexico the dirt and rocks are almost purple!!

[Kathryn]

Some of the soil in north and central Louisiana is red like this so I looked up the Red River (which flows from Texas to Louisiana then into the Mississippi river) on Wikipedia. It stated that the redness in the Red River is due to eroded Port Silt Loam from Oklahoma, which is reddish in color due to the weathering of reddish sandstones, siltstones, and shales of the Permian geologic era.

Also: Soil color is primarily influenced by soil mineralogy. The extensive and various iron minerals in soil are responsible for an array of soil pigmentation. Color development and distribution of color within a soil profile result from chemical weathering, especially redox reactions. As the primary minerals in soil-parent material weather, the elements combine into new and colorful compounds. Iron forms secondary minerals with a yellow or red color; organic matter decomposes into black and brown compounds; and manganese forms black mineral deposits.

Interesting.

[Tad]

resurection fern in red dirt

[Mats]

Matt, I think you're planning on living in your new home for a long time and will be putting a lot of plants in the ground.  If I were you, I would invest $100 and get a good soil analysis done.  

A company like Wallace Labs can tell you everything you need to know about your soil.  

Here are a few paragraphs from Robert Smaus' (former long-time garden editor of the LA Times) '52 Weeks in the California Garden' chapter on "Why leaves turn yellow".  (It has nothing to do with your question about red soil, but may show you the importance of knowing as much as possible about the soil you're planting in.)

"Garn Wallace, of Wallace Laboratories in El Segundo, which also runs tissue and soil tests for professional and home gardeners, is convinced that chlorosis is the culprit in a majority of cases, but adds some interesting qualifiers. While iron is plentiful in California soils (perhaps five percent of our soil is iron by weight), what makes it unavailable to plants is the soil alkalinity, which, he says, is caused by lime. (Gardeners who are from the East Coast, or who heed gardening books written by eastern authors, should note that lime is a problem here and should never be added to a soil. In the east, it is frequently recommended to tone down the natural acidity of their soils.) To counteract the lime in our soils, he says, every gardener should add gypsum to the soil every time it is turned or prepared for planting.

    In addition, Wallace suspects that a number of heavy metals, such as copper, some found in soil amendments that contain sewage sludge, interfere with the uptake of iron, and that cold, heavy, waterlogged soils do the same. He always expects to see a lot of chlorotic yellowing after wet winters.

    His solutions? Improve a soil where you are going to plant or replant by adding gypsum and organic matter. Gypsum has many benefits: It reduces salinity, subdues heavy metals, binds organic matter to the soil particles and the like. Add about 50 pounds for every 1,000 square feet. (Be careful, you can overdo it, especially if you live in Gypsum Canyon in Orange County!) Homemade compost is the best soil amendment, but if you don't have any, add mushroom compost, peat moss or other organic matter so it becomes about 10 to 20 percent of the soil volume. If you are cultivating to a depth of a foot, that would be a one- to two-inch layer. Wallace says manures are okay if you use only 10 percent by volume, because of the salts they contain.

    Where there are yellowing permanent plantings, such as trees and shrubs, and you do not want to turn or disturb the soil, scatter chelated iron over the surface. Wallace favors a product called Sequestrine 138SE because it gets to work faster. He calls it a "designer chelate," because its formula was carefully designed years ago at UCLA. But all forms of iron chelate work with time.

    "Vertical mulching" is another idea from Wallace for yellowing permanent plantings. Dig holes near the effected plants and fill them with improved soil, mixing in amendments such as homemade compost, sludge, mushroom compost, manure or--his least favorite--shavings and sawdust, the kind sold by the bag at nurseries. He has dug holes and then a few years later found them stuffed with roots, all able to take up nutrients needed by the plant. For trees, he suggests digging four or five holes, two to three feet deep and a foot wide, spaced evenly around the tree out near the drip line, the edge of the tree's canopy. You could even use a post-hole digger.

    To help acidify the soil, which makes iron more soluble and usable, sprinkle soil sulfur on the surface and water it in. Again, Wallace has a favorite product, DisperSul Plus Fe Mg, which also contains some needed iron (and manganese), though it may be hard to find at nurseries. Follow label directions--it is possible to use too much sulfur.

    If you think your problem is serious, or want to fine-tune your solutions, get a soil test or leaf tissue analysis done by a professional lab, usually listed under Soil Testing in the classified section of the phone book. A soil test costs about $70 and tissue analysis between $50 and $70. You might find that you actually have one of the 1,000 other reasons leaves turn yellow."

.

[JakeK]

Matty and Matt both got it right. It's iron oxides in the soil. Rainforests have deep red and orange clay soils from all the iron oxides, same with the S.E. U.S.

[fiji jim]

Here red clays and soils have iron oxide and arsenic in them. Most things grow ok in it as long as the clays are not too solid and water-logged. Usually acidic also.

[ariscott]

Come to Australia... we got lots

Regards, Ari

[Gonzer]

Matty, that looks suspiciously like a cactus and not a Polypodium fern?

[amazondk]

The overwhelming majoirty of Brazil has red soils of laterite composition.  I guess the Wikipedia description below explains it pretty well.  In Brazil what is known as "terra roxa" or purple soil is the best for agriculture. These soils were formed when Africa and South Amercia split up.  

Laterite is a surface formation in hot and wet tropical areas which is enriched in iron and aluminium and develops by intensive and long lasting weathering of the underlying parent rock. Nearly all kinds of rocks can be deeply decomposed by the action of high rainfall and elevated temperatures. The percolating rain water causes dissolution of primary rock minerals and decrease of easily soluble elements as sodium, potassium, calcium, magnesium and silicon. This gives rise to a residual concentration of more insoluble elements predominantly iron and aluminium.

Laterites consist mainly of the minerals kaolinite, goethite, hematite and gibbsite which form in the course of weathering. Moreover, many laterites contain quartz as relatively stable relic mineral from the parent rock. The iron oxides goethite and hematite cause the red-brown color of laterites.

Laterite covers have mostly a thickness of a few meters but occasionally they can be much thicker. Their formation is favoured by a slight relief which prevents erosion of the surface cover. Laterites occurring in non-tropical areas are products of former geological epochs. Lateritic soils form the uppermost part of the laterite cover; in soil science specific names (oxisol, latosol, ferallitic soil) are given for them.

[palmmermaid]

Here in Florida where we have areas of white sand, if you dig down a couple of feet, you will see the sand change color to a reddish brown.  The rainwater leaches the minerals out of the sand, leaving it a bleached white color.  I think a lot of our color is due to the remains of shells that have been turned into sand by erosion or fish.  We do have 3 kinds of sand here in Florida, depending on your location.  We also have 3 kinds of limestone.  Up around Tallahassee and Quincy, we have a lot of clay, deposited by the rivers and old ice flows from Apalachia.  The geology of the state is very interesting.

If you go out to a place called Twenty Mile Bend near Lake Okeechobee, you can see the difference between the old dune line and the lake bottom.

[steve 9atx]

Matty

Call one of your State Universities that has an Ag program.  If they're like Texas A&M used to be, they'll do your soil analysis for free.  Sometimes County Ag Extention Agents have the same capabilities.

Steve

[Kris]

Dear Matty  

we have red soil & clayee soil in plenty in south india.and when i dug the huge pits for palms.the clay portion was removed and refilled with 4 parts loose sandy soil : 2 parts of red sand :3 parts of dried leaf mulch from our dycot trees.

even in my plastic barrels the ratio is the same...

here are some visuals !

love,

Kris  

And by the way all the plants here seem to love this mix,leave alone palms or cycas...

[Kris]

one more close-up !

[Kris]

Some soil preparation stills....!   the work was carried out in our roof top terrace area.

[Daryl]

Lots of red soils in OZ. Iron oxide adds the colour. Around here the red soil is called 'Terranora Red' or 'Volcanic Red' as it is derived from volcanic basalt that is millions of years old. It is a very rich soil, and most plants love the stuff. Here is what it looks like...

Daryl

[Kris]

Dear Daryl

lovely still and the pulmeria plant looks great !

love,

Kris  

[sonoranfans]

Yes Iron oxides are the source of the color, they're all over the southwest.  there are many different iron oxides of different coloring, red/brown to orange to black.  I also live in an area where the soil pH is around 10, way too high for most palms.  I am a chemist by training(Doctorate) and have read extensively about soil remediation/soil chemistry.  Gypsum is CaSO4, and has a mild effect, not good enough for high pH soils in my opinion.  Sulfur is much more powerful, but needs microbes to break it down before it gradually makes H2SO4, sulfuric acid.  the sulfuric acid then in turn reacts with the calcium in clay soils(there is a lot of Ca in clay soils) to make CaSO4, gypsum, like this:

H2SO4(sulfuric acid)+CaO(calcium oxide) -> CaSO4(gypsum) + H2O

or for non oxidized calcium(often calcium is bonded to calcium, causes poor drainage by blocking water):

H2SO4(sulfuric acid)+Ca(calcium) -> CaSO4(gypsum) + 2H+(acid)

 The key is that you ONLY need to add sulfur to create gypsum IN THE SOIL with a much bigger impact on the pH by releasing acid.  It also consumes calcium oxide which is another source of poor drainage in clay soils as it is hygroscopic.  Gypsum WILL NOT substantially consume Calcium Oxide or react with calcium bonded to calcium and improves drainage only by adding drainable components, not by changing the soil chemistry.  Sulfur will take years(perhaps 5 years) to change the soil chemistry, but it will be permanent and it will be less work(much less work) and more effective ultimately than gypsum( a weak acid).  Dig/mix the sulfur into the top 3" or so of soil around your drip emitters or drip hoses, drip lines of palm 2x a year.  It works great for roses, and for palms.  It will take about 3 months to break down and impact the soil pH(and the trace mineral solutilities, see below), so plan ahead.

If you want to change the soil pH quickly use aluminum sulfate(AL2(SO4)3), but be careful as it will work in a non time release fashion, it can burn plants unlike sulfur.

Why change the soil pH if it is high??

For palms, it makes the traces of iron, magnesium, and manganese, bioavailable for your palms.  These elements are insoluble at high pH(they exist primarily as insoluble hydroxides), hence they are not available to the palm.  Many palms will suffer mineral deficiencies when planted in high pH soils even though you add the elements in fertilizers.

[MattyB]

Thanks for that lesson Tom.  Very interesting.

[osideterry]

Unlike most of us armchair experts, Tom is a REAL scientist. I don't understand what he is saying most of the time, but I sure as heck follow his advice. I definitely want to stop by and see his garden next time I'm in the general Phoenix or Tucson areas.

[Dave-Vero]

The red soils of the southeastern US Piedmont are similar to those of Brasil, something soil scientists at NC State University realized 30 years ago.

[Fouquieria]

Years ago when I took a class in geology, I think I read where California had one of the largest groups of soil types in the world (along with China).

Anyway Matty, here's a simplified SoCal explanation on soils.  Hope it helps.

-Ron-

http://www.rain.org/global-garden/soil-types-and-testing.htm

[sonoranfans]

(osideterry @ Oct. 03 2007,15:43)

QUOTE

Unlike most of us armchair experts, Tom is a REAL scientist. I don't understand what he is saying most of the time, but I sure as heck follow his advice. I definitely want to stop by and see his garden next time I'm in the general Phoenix or Tucson areas.

If someone would pay me more to be an armchair expert I'd do it in a minute Terry.  I guess I may have done things the hard way, I get paid pretty well, but it wasnt and isnt easy.  My cousins and brother in law do way better than I and dont seem to have as hard a time of it.  Hey if they would pay me enough to live in San Diego and buy a house there, I'd do that too.  San Diego is one of my favorite places in the continental US.  I'm not a palm expert thats for sure, but I'm learning alot here on this board from some experienced and knowledgable people.  I do know a little soil chemistry or my palms would probably be sick or dead.  I apologize to anyone here who found my rantings uninformative, its not simple stuff and I dont know how good I am at explaining it to lay people(non chemists).  If I can clarify any part of it to anyone, just send me an email I'd be happy to do it.  

And Terry if you ever plan to be in the Phx area, send me an email to let me know,  I'll make sure you get enough to drink and eat and a place to sleep if you get too much to drink.

[MattyB]

Great stuff, thanks Ron.  I better not shake the jar too hard my rocks will break it!  haha

[BS Man about Palms]

Great info here, Thanks guys!!!  

[Alicehunter2000]

We never had a problem with dogs eating the clay here ..........only people. Supposed to be good for you ...... so they say. My folks used to have to run them off when I was a kid because they would cause all kinds of erosion problems on the hillside with their digging. I believe it was the white clay they were going for.......I think this appetite for soil came from their ancestors in Africa where eating clay also occurs. Just a tidbit of info for you trivia buffs. Anybody else ever heard of this?