Clay soil is one of the most common soils found in the world. Clay soil is characterized by its hardness and resistance to erosion. The term “clays” refers to a combination of minerals such as kaolinite, siltstone, sandstone, dolomite and other rocks. These minerals are often mixed with water or sand to form clays which are then left out in open air for long periods of time. These clays are not only hard but they have high permeability. They allow water to pass through them easily and do not retain moisture well. Thus, clay soil is very good at retaining water. However, it does lose some of its moisture over time due to evaporation from the ground surface or rainwater runoff into the soil.
The main problem with clay soil is that it tends to dry out quickly if not protected from extreme heat and cold. Therefore, it is best suited for areas where there are frequent hot and humid summers followed by cool and rainy winters. Also, clay soils tend to drain slowly, so they are not suitable for large areas like deserts or arid regions. Clay soils may also become compacted during heavy rains when the top layer of soil collapses under its own weight causing subsidence.
There are two main types of clay soils: montmorillonite and kaolinite. Montmorillonite is also known as shrink-swell clay as it tends to move around when wet and then shrinks back again when dry, causing the land to subside over time. Kaolinite, on the other hand, causes expansion when wet and does not shrink back when dry. Both these types of clays could be found in the same area.
There are many ways in which you can identify if the soil in your location is primarily clay. First and foremost is its appearance. If you take a handful of moist soil and roll it into a ball then drop it into a glass of water, it will sink. This happens because the individual clays that make up the soil have a negative electric charge called “hydration” which causes them to repel each other. If the soil has mainly clay, then the clumps of soil will fall apart as soon as they are wet and it will seem to “flow” slowly though your fingers.
This is in comparison to the sand in your soil mix, which will form a solid ball that will not break up and will drop quickly through the water. A simpler test for identification is to take a handful of soil and let it slowly run out between your fingers. If the soil is mainly sand, then you will be left with a small pile of soil at your fingertips. If there is a lot of clay in the soil, your fingers will be left covered in a thin film of the stuff.
Both types of clays are usually red or brown in color and when mixed with water become very slippery. When dry they can be crumbled easily between your fingers. When mixed with water they become hard to crumble.
Clay soil is sometimes mistaken for soft or muddy ground, but this is not always the case. A good way to check if you are in a clay area is to look for vegetation. Trees and plants in soft or muddy ground will not grow or will die as the ground cannot easily support their roots. In clay, however, the fine rich soil is easy to dig and as it contains a lot of minerals it means that plants will easily grow and are able to thrive.
One last thing to mention about clays is that they can be mixed with other soils to make them more fertile. This is especially useful when trying to create hard surfaces like roads or foundations which need a solid base. The mixture for this is usually 2 parts sand to 1 part clay and 1 part sewage waste or crushed brick. This should then be mixed with water until you get a solid concrete like substance that is easy to work with.
Sand is usually found in large areas of land, especially deserts and coastal beaches. It is one of the components of concrete and therefore an important resource when building.
As well as being easy to spot, it is also easy to identify by its feel and appearance. If you take a handful of sand and let it fall through your fingers then you will be left with a small pile. Although the individual grains can be seen easily, they are not closely packed together and are able to fall through each other. If you pick up a handful of dry sand and then pour it into a glass of water, the sand will stay separate and not form a blob at the bottom.
Sand itself does not contain many nutrients, but it is an excellent filler to make other foods go further and can also be mixed with clay to make a mortar for bricks.
Unsurprisingly dirt is very easy to spot in the landscape as it is usually a mixture of all the other types of soil. It can be a combination of sand, clay and soil and therefore will have all the properties associated with these.
If it is not deep enough to call it soil however, then it is just called dirt. This usually means that it is less than 40 centimeters down, but this varies depending on your biome and how the land has formed. For the purpose of this book however, anything shallower than 40 centimeters will be referred to as dirt.
Dirt is usually a sign that you are not very far from an area of soil of some description. It may even be possible to dig down and reach soil in a small area if you are in a small patch of dirt.
Sometimes it is not very obvious what the soil type is in an area as it has been mixed up with debris (weed, paper, old cans etc). It is still worth spending time to check it as you may be in a soil area after all.
If you are sure that you are in a dirt area then you need to decide if this is actually the area you want to set up your shelter in. Some points to consider:
It will be easier to defend from other players if you are in a soil area as it will be easier to dig a bunker.
Soil areas can support larger groups of people. If you are planning to team up with others then it would be better to have a larger population nearby.
Soil areas can be cultivated (see farming) to grow your own food. This can greatly increase your survival chances as self-sufficiency is always a good thing. It is also an advantage if the disease has hit urban populations hard as there will be a lot less competition for the resources out in the country.
Setting Up Your Shelter
Once you have decided on a suitable location you need to set to work. If you haven’t already chosen your team-mates then this is the time to do it. It’s always better to work in a group of at least two as you can share the workload and keep each other’s spirits up. There may be times when one of you is sick or injured so it’s good if you all get along well.
Sources & references used in this article:
Picloram and aminopyralid sorption to soil and clay minerals by BJ Fast, JA Ferrell, GE MacDonald, LJ Krutz, WN Kline – Weed science, 2010 – BioOne
State soil geographic (STATSGO) data base for the conterminous United States by GE Schwarz, RB Alexander – 1995 – pubs.er.usgs.gov
Clay dispersion, infiltration, and erosion as influenced by exchangeable Ca and Mg by KM Dontsova, LD Norton – Soil Science, 2002 – journals.lww.com
Soil erodibility as determined by raindrop technique by DK Rao, G Rao, PRT Pranav – Int J Eng Innov Technol, 2012