Questions about soil

[Wild Bill Kelso]

Ask away and I will do my best to answer them

Wiki on Soil

[MrMofo]

you've started a thread about dirt and then pointed us towards wiki which tells us all we need to know about dirt and then you say to ask you about dirt.

Is this some sort of test on how well you've read about the wiki dirt?

[eisenkopf]

The first reply actually shows that much more information and education about soil is needed. The majority seems indeed to equal it with dirt, which could not be more wrong. The degradation of soil through human influence (unsustainable agricultural practices, sealing of surfaces through housing or streets, unstustainable consumption of groundwater, etc.) actually is one the most pressing envinronmental issues everywhere. It takes thousands of years to "grow back" soil, if at all. While we continously increase our global "footprint", the area on which these footprints are left is decreasing.

Wild Bell Kelso, are you a pedologist? I studied pedology for a few years, before it became too complicated for me

[Wild Bill Kelso]

The first reply actually shows that much more information and education about soil is needed. The majority seems indeed to equal it with dirt, which could not be more wrong. The degradation of soil through human influence (unsustainable agricultural practices, sealing of surfaces through housing or streets, unstustainable consumption of groundwater, etc.) actually is one the most pressing envinronmental issues everywhere. It takes thousands of years to "grow back" soil, if at all. While we continously increase our global "footprint", the area on which these footprints are left is decreasing.

Wild Bell Kelso, are you a pedologist? I studied pedology for a few years, before it became too complicated for me

Yeah, I am doing my PhD in Soil science focusing in soil microbial ecology and biogeochemical cycling. Currently I am doing work on reclaiming the oilsands areas in Alberta. unfortunately, general knowledge on soils and how they function is lacking in both the general public and among specialists. People have to remember that the failure of many ancient civilizations is directly linked to soil degradation.

[The Devil's Sergeant]

Yeah, I am doing my PhD in Soil science focusing in soil microbial ecology and biogeochemical cycling. Currently I am doing work on reclaiming the oilsands areas in Alberta. unfortunately, general knowledge on soils and how they function is lacking in both the general public and among specialists. People have to remember that the failure of many ancient civilizations is directly linked to soil degradation.

Was it always your life long ambition to play in the mud?

[chamaeleo]

Yeah, I am doing my PhD in Soil science focusing in soil microbial ecology and biogeochemical cycling. Currently I am doing work on reclaiming the oilsands areas in Alberta. unfortunately, general knowledge on soils and how they function is lacking in both the general public and among specialists. People have to remember that the failure of many ancient civilizations is directly linked to soil degradation.

Sounds like cool research. Are you looking for the ideal microbial community for consolidating hydrocarbons into mine-able deposits? Most of my knowledge comes from the polar opposite, in bioremediation, where communities that munch on complex organic compounds are highly prized. You might find suitable bugs in petroleum-bearing strata much deeper than your oilsand deposits.

I've got a question: I live on a flood plain in NM that'd been farmed for the past 400 years in the old Spanish land-grant style...makes for pretty nutrient deficient, alkaline soil, since most actual floods were mitigated by the network of aceqias. When I moved in, ~50% of the ground was hardpack sandy clay capped w course river gravel.

I have since scraped most of the gravel away (good exercise, bad for lungs) and replaced it with 2-3" of pine wood shavings from a local lumber yard. I was thinking that adding so much pine mulch might deplete what little nitrogen there is (correct?), so, what would you recommend as the best way to buffer the mulch? I'm planning to spread compost, but if you know an easier/cheaper method I'm all ears. I'd eventually like the place to have a forest-floor appearance...since lawns are so bourgeois...

[Wild Bill Kelso]

Sounds like cool research. Are you looking for the ideal microbial community for consolidating hydrocarbons into mine-able deposits? Most of my knowledge comes from the polar opposite, in bioremediation, where communities that munch on complex organic compounds are highly prized. You might find suitable bugs in petroleum-bearing strata much deeper than your oilsand deposits.

Actually, I don't deal with the extraction or remediation of hydrocarbon contimanted soils. basically with oil sands you are left with huge amounts of redisual sand and the overburden that was above the oil sands. The aim is to take this material, recontour the land and cover it with a cap of clean sand. This cap is then to be the new medium for the forest to grow in. I am looking at various reclamation treatments and how the microbial communities they have in them compare to communities in natural site. The goal is to jump start the soil to a self-sustaining system in 25 years where mother nature took 6000. it is a pretty lofty goal, but I am confident it can be done!

I've got a question: I live on a flood plain in NM that'd been farmed for the past 400 years in the old Spanish land-grant style...makes for pretty nutrient deficient, alkaline soil, since most actual floods were mitigated by the network of aceqias. When I moved in, ~50% of the ground was hardpack sandy clay capped w course river gravel.

I have since scraped most of the gravel away (good exercise, bad for lungs) and replaced it with 2-3" of pine wood shavings from a local lumber yard. I was thinking that adding so much pine mulch might deplete what little nitrogen there is (correct?), so, what would you recommend as the best way to buffer the mulch? I'm planning to spread compost, but if you know an easier/cheaper method I'm all ears. I'd eventually like the place to have a forest-floor appearance...since lawns are so bourgeois...

I imagine the land would be very depleted in nutrients especially since the flooding no longer occurs. The soil would also be very old since it would have escaped glaciation, meaning most of the nutrients in the surficial mineral layers would have long ago been percolated into the water table.

Removing the coarse stones is a good idea if you wish to grow any plants in it. Mostly to make working the ground easier. The mulch you applied won't deplete the nitrogen, but it also won't help plants grow either (if that is your goal). The problem with straight wood chips is that they are very high in carbon and contain relatively little nitrogen. Any fungi that decompose the wood will use more nitrogen then what is provided by the soil, so yeah it will remove it from the system. Now what this means is that the wood chips will be there for a long time, and not much else will grow. if you want to make the material more favourable for plant growth then I am afraid compost or some topsoil is your only option. I wonder is it possible to mix the woodchips into the sandy clay with a rototiller? It may make it a more suitable planting medium then just straight woodchips as that way there would be a variety of microbial habitats and the resident microbail population in the sandy/claywould then have access to the woodchips. This may work well with some compost mixed into it.

What I woudl suggest is you find a corner of your yard and have a mini experiment. Buy one bag of compost and rotorill it into the woodchips and sand, and then next to it try just woodchips rototilled with sand, and finally your third section would have the woodchips on top of sand. See what happens during the year and then you can make a decision on how to do the rest of your yard.


I am curious to know what kind of ecosystem you are living in? Is it arid/montane? If you want a forest floor appearance then you will need a tree. If you are going for a natural look and don't want to water your lawn then I would suggest you find some native species that are adapted to the area (if they are available and depending on their cost). I think it would look cool if you have a yard with a ponderosa pine with the grass/shurb understory

[Copperknickers II]

I have a question. What happenes to soil that is under tarmac? What would it be like if we were to dig up a 2000 year old road/a city center? Do buildings compress the soil? And what was there before organic life, a world without soil?

[Wild Bill Kelso]

I have a question. What happenes to soil that is under tarmac? What would it be like if we were to dig up a 2000 year old road/a city center? Do buildings compress the soil? And what was there before organic life, a world without soil?

Generally, soils under tarmac have had all of thier top layers removed, and are heavily modified and compacted. Also, soil forming processes will have pretty much ceased since there is limited percolation of water and no accumulation of plant roots/organic matter, teh same thing would apply to buildings. If you want to see what the world would be like without organic life then all you need to do is look at a photo of mars, or if you want an example that is a little closer to home, look at areas with recently receded glaciers.

[Godfrey I of Leuven]

Okay: Why do I always get dirt under my fingernails ?

[Sphere]

I'm a Civil Engineer, so if something grows in it, it isn't soil.

Soil Mechanics actuallly has some rather complicated mathematical theory behind it, which is counter intuitive because it is often the building component that an engineer has the least control over and least information on. The theory may be complex, but getting a result within 100% of the actual value is considered very good.

As to the dark sticky stuff that plants grow in, you need to dig that stuff out and get rid of it unless you want huge settlement of your foundations.

[Wild Bill Kelso]

I'm a Civil Engineer, so if something grows in it, it isn't soil.

Soil Mechanics actuallly has some rather complicated mathematical theory behind it, which is counter intuitive because it is often the building component that an engineer has the least control over and least information on. The theory may be complex, but getting a result within 100% of the actual value is considered very good.

As to the dark sticky stuff that plants grow in, you need to dig that stuff out and get rid of it unless you want huge settlement of your foundations.

I guess the term soil depends on your profession I believe your term for soil is what I would call surficial geological strata. Same would go for the surface of Mars. My definition of soil and the one which I hope to discuss in this thread requires biological activity. And you are correct, building on top of organically enriched mineral soil is a bad idea. There is a library built near where I live that was constructed on a topsoil stockpile. Little did the builders know that 10 years after completion the organic matter under the building would be converted to methane gas.

[Playfishpaste]

What are the unique advantages of muck farming?

And from your knowledge of soil, could you make some comparisons in efficiency between it's use in botany as opposed to hydroponics?

[chamaeleo]

What are the unique advantages of muck farming?

And from your knowledge of soil, could you make some comparisons in efficiency between it's use in botany as opposed to hydroponics?

For one thing, soils host a diverse community of microbes and fungi which are beneficial if not essential to many plants. Hydroponics is great for boosting production, but I'm not convinced that the yields are as nutritious regarding certain trace minerals.

Kelso: great info, re my yard. I like the idea of a test strip. I like the excuse to buy a rototiller even better...hand-tilling my measly 4x8' raised bed this year sucked.

A stray thought drifted into my skull whilst riding home last Fri...lawn clippings! I don't have a lawn as such (a small strip, just large enough to play Bocce ball) but many neighbors do. As long as they don't treat w pesticides & herbicides, they could give me their clippings rather than pay for removal, and I could blend it in w the wood chips.

I'm not sure how old my soil is, but the last time my yard flooded was in 1904 (the year before my adobe house was built). I'm ~3 km from the "mighty" Rio Grande, elevation-wise there's little difference; I think the water table is only 10' down.

Unlike most of Albuquerque, my area (and my yard in particular) has tons of trees (El Bosque). 5000' elevation makes for intense sun and wind, so evaporation is high. I don't so much want to cover the entire yard with a new O layer, as I want to limit dust/mud and retain moisture in the soil. The straight woodchips are doing the trick but I don't want them affecting the trees & bushes they enclose.

I can get 1 cu yd (the bed of a compact pickup, filled to brim) of organic compost for $32...the equivalent in Home Depot cu ft bags would run ~$130. I'm thinkin 2-3 loads would allow me to blend a 1" layer across a lot of chips.

Meanwhile, the compost pile just keeps up with my planting frenzy. I've had to be really careful lately, nearly speared a couple of toads with my pitchfork over the weekend...