# Tag Info

47

The Dustbowl occurred during the 1930s because of a combination of man-induced drought and the (mis)use of relatively new farming practices. In the 1920s, the spread of automotive (and tractor) technologies made it possible to "plow up" the Great Plains. This resulted in the loss of a lot of natural moisture and the creation of drought conditions in lands ...

46

Yes. In fact, there are sand-dunes in Antarctica [1:15].

21

As always: It Depends. Assuming enough water and sunshine, crop growth rate boils down to the concept of limiting nutrients. These may be: nitrogen (via ammonia or nitrates), phosphorous (via phosphates), potassium, and sometimes others. In typical continental settings (i.e. subduction related vulcanism), lavas may be enriched in potassium and phosphorous ...

13

Soil is an interesting case because although it is non-renewable (at any useful rate) as a 'bulk material' once removed from the ground, the nutrient content of soil can be renewed with fertilizers. What a soil-scientist would understand as 'soil' is ultimately produced from the physical and chemical breakdown of solid bedrock at the base of the soil ...

11

This LiveScience article suggests the areas aren't major: The scant areas that are free of snow and ice make up less than 0.4 percent of the continental land mass. In places there, the wind has built sand dunes. This article by Burton-Johnson et al., 2016 on automated satellite analysis methods, summarized in this DailyMail article, indicates refined ...

10

So let's get through some definitions. I will not discuss the derivations of this, but you can look this up, if you want to in the source I provided. We find ourselves in a porous medium, so we will have always some volume filling factor $\Theta$ of water in rock. (copyright K. Roth, Heidelberg University) Then we can start with the hydraulic ...

10

Sugar can be used as a weed killer, particularly broad leaf weeds, rather than grasses or perennials. It is a carbon nutrient that contains no nitrogen. Sugar can limit the growth of plant that do not tolerate low nitrogen environments. This is because microorganisms in soil are forced to source their necessary nitrogen from soil. This leaves little for ...

9

The Dust Bowl was caused by farmers tilling up too much soil. However, there were also other factors. Weather also played a key role. Because there were several years of drought, and farmers had plowed up so much ground, when high winds came along the soil was blown off the ground, and the rest is history. This became somewhat of a vicious circle: no crops ...

9

Soil color is highly dependant on the oxides and other minerals in the composition. Purplish tones appear to be possible by inclusion of manganese oxide compounds. There are locations in China that have markedly violet soils. If you broaden your search to sands as well as soils, there are plenty of examples of garnet-based sands that can appear markedly ...

9

tl;dr Silica is everywhere, in everything. The amounts can be close to 100% in quartz sand, or less than 1% in things like peat or limestones (and derived soils). Finding completely pure soils (let's say less than 0.1%) is wishful thinking. Silicon dioxide (or silica, or silicon oxide, it's all the same thing) can exist in two "forms": As the compound, ...

8

From this paper from 1958 (page 2), ... gaseous nitrogen of the atmosphere represents a vast store of potential fertility. It is not directly available to plants. Nitrogen-fixing bacteria, how- ever, absorb this gas from the soil solution and convert it to cell protein. When the cells die, other microbes attack the protein and convert the nitro- ...

8

Soil color is largely determined by it's composition. There are three main components in soil: Gravel, sand, and silt. In essence, the type of stuff you find in sedimentary rocks. Usually, this is mostly silicate minerals like quartz, feldspar, and mica, and is usually pretty bland in terms of color. In theory, certain silt minerals (olivines for example)...

8

Karkar is made of calcium carbonate. then why it happens only in arid soil? Because this is what happens to calcium carbonate in wet environments: It dissolves away, forming a cave. Calcium carbonate, or calcite, is soluble in mildly acidic solutions. Rainwater is mildly acidic because of CO2 from the atmosphere dissolving in it, so it never allows for ...

7

It depends on which classification system you're using, which varies by country. According to the USDA Soil Taxonomy, R is used to designate bedrock. Other countries and classification systems may (or may not) use different letters. Check out the Compendium of On-Line Soil Survey Information for other classification systems. To answer your second ...

7

According to Wikipedia and Nature.com, "R Horizon" is the official letter for bedrock. CAPTION: Example soil with designations that communicate the soil formation processes occurring in each horizon.

7

As far as I know, there’s no one definitive pedo-transfer function (PTF) but there have been several studies that train functions against multi-site databases, rather than just deriving site-specific functions. These PTFs typically define soil moisture-conductivity-suction relationships based on silt, sand and clay fractions from which you can read off ...

7

Erratic Climate Lets take Broome, Australia as our example. Broome gets 615mm of rain a year (24 inches), including 58/182/180/102mm in Dec through March. Coupled with average highs in the low 90s, this would be fine for the sort of agriculture you see in South Texas. However, Broome's rainfall is very erratic. For example, in 2016, the rainy season started ...

6

Denitrification requires anoxic conditions, organic matter, and NO3-. Gleysols are anoxic soils formed in wetlands. Waterlogged wetland soils are generally both anaerobic and high in organic matter. For a given concentration of NO3-, denitrification rates should be higher in Gleysols than similar soils that are aerobic soils (because there will be less ...

6

Unfortunately, the color itself won't give you much more information than the amount of organic matter and oxides/hydroxides. The amount of carbonate and some silicates might also be detected, but those values would be very vague without further examination of the soil. If you want to get more information you would need some more data. The grain sizes for ...

6

Like many things in Earth Science, the answer is, "It depends." In this case it depends on the composition of the soil and the contaminant you are talking about. Climate, particularly the amount of precipitation, can also have an effect. Septic systems are primarily designed to promote aerobic conditions and aerobic bacteria to degrade organic compounds ...

6

A frost-gley is a waterlogged permafrost soil. IOW, a gleysol that has undergone cryoturbation.

6

From Mary, et al., 1996, Figure 1 on the second page shows a nice breakdown of there the Carbon and Nitrogen go when a plant decomposes. Hadas, et al., 2002 has experimental data from plants with C:N ratios from 11:1 to 136:1. In summary, most carbon ends up in microbial biomass or as CO$_2$. If the process is allowed to proceed to infinity, then ...

6

There are two main problems that "wear out" soil, and people working on this deal with both of them. A soil might be low in organic matter and nitrogen, perhaps because all the crops were sold away and the topsoil eroded off. This would also happen on a new sandbank, or where a landslide had revealed a lot of subsoil. Naturally what happens is that the site ...

5

Curved trees are a sure sign of movement of surface. Special geomorphic shapes are also present in a slowly developing landslide. At the top of the landslide cracks can start to show, at the foot you can find "bumps" in the soil. Water will have difficulties to drain at the foot of the landslide. Here are a few examples of literature that should be ...

5

Regarding your question: So now I'm wondering if that might be the "fire layer" where the excessive heat hast left its mark in the ground. The short answer is no. The layer seems to be about 1 meter thick. No bombardment related fire can cause blackening 1 meter deep. Now, why is it "black"? First of all, it's not black. It's dark brown. I've seen black ...

Only top voted, non community-wiki answers of a minimum length are eligible