All About soil

[Music] soil is the loose material that covers the Earth's surface in most parts of the world land is covered by soil you can think of soil as the living skin of the earth it gives plants the nutrients they need to grow and plants give people and animals food to live soil also provides building materials homes for animals and things we use every day soil is not just dirt it is an important natural resource that provides the foundation for life on Earth [Music] soil is made of rocks decayed plants and animals air and water let's first look at rocks through a process called weathering big rocks break down into smaller and smaller pieces eventually becoming part of soil soil does not form in a day it can take hundreds of years wind water an extreme hot and cold temperatures cause rocks to break down over time the pieces of rock are transported from one place to another through erosion but wait soil is not just tiny rocks it is also made up of decayed plants and animals called houmous houmous is made from things that were once alive like leaves that fall from a tree the dead leaves decay or break down and become part of the soil giving it nutrients houmous is a dark color and is found on the ground surface there are three layers of soil the top soil is the top layer where plants grow and it is only a few inches thick houmous is part of the top soil the middle layer is the subsoil and it is a combination of soil and rocks bedrock is the bottom layer that is made up of many layers of rock [Music] [Music] how soil looks and feels tells us about its properties is it good for growing plants how much air and water does it hold to answer these questions let's start with soil types there are three types of soil sand silt and clay soil comes from tiny pieces of weathered rock the difference between soil types is the size of the rock particles sand has the largest particles it feels rough and gritty sandy soil has air spaces between the grains of sand the air space lets water drain through sand quickly a sandcastle washes away in the tide because sand does not hold on to a lot of water silt has medium sized particles it feels smooth when wet silt particles hold on to more water than sand a bird's footprint sticks to silty soil because silt does not drain as much water clay has the smallest particles it feels sticky when wet and hard when dry the small rock particles packed tightly together holding the most water but there is little space for air the water helps clay keep its shape so it is used to make pottery what is the best type of soil for growing plants sand does not hold enough water for most plants to grow clay holds water but does not contain the air that plants need the best soil for growing plants is called loam and it is a mixture of sand silt clay and houmous houmous is made of decaying plants and animals it adds nutrients to soil and gives it a darker color the combination of soil and houmous makes loam the best soil for growing plants because it has the perfect amount of air water and nutrients plants get the food and water they need to grow from soil plants absorb food called nutrients from their roots besides providing food and water soil helps plants stand tall by holding their roots in place when roots take hold in the ground they keep soil from washing away for example tree roots prevent soil erosion by reaching deep and holding soil together farmers want to plant their crops in the best soil with the most nutrients to prepare soil for planting seeds a farmer uses a tractor to till the soil tilling mixes up the topsoil so the nutrients are near the surface crops grow in different types of soil rice grows in soil with clay that holds a lot of water pineapple grows in sandy soil and carrots grow best in a mixture of soils top soil where plants grow is a precious natural resource because it takes a long time for rocks to become soil farmers try to conserve the topsoil by rotating the kinds of crops they plant and by controlling irrigation so soil doesn't wash away when crops are harvested the farmer lets the plants left behind decay and become part of the soil again giving back nutrients [Music] worms spend their lives eating soil they feed on decaying plants and leaves within the soil and this behavior helps make soil healthy let's look at an earthworm under a microscope a worm does not have eyes legs or teeth but it does have strong mouth muscles to swallow tiny bits of soil worms move forward and back eating what's in front of them the soil passes through the worms digestive system and comes out the other end as waste called castings these are worm castings and they are rich in nutrients for plants worms help soil in other ways after it rains worms crawl deep underground creating tunnels worm tunnels are important because they mix up the soil allowing air and water to get inside to help plants grow since worms are so helpful farmers raise worms just like other animals this is a worm farm where millions of wriggling earthworms are raised and then sold to other farmers to keep their soil healthy [Music] [Music] people and animals rely on soil to grow plants for food but soil has other uses as well this animal is a mole moles live underground digging tunnels to look for worms and insects in the soil many animals such as the Kitfox the burrowing owl and the tiger salamander live in burrows beneath the ground around the world there are people who make their homes out of soil wet soil made of sand and clay is poured into rectangular molds the mud bricks also known as adobe bricks are stacked on top of each other to create the walls of a building [Music] here are examples of buildings made of soil bricks [Music] clay soil can be used to make pottery a lump of clay is molded by hand into cups bowls and vases people in some cultures use the natural colors in soil to paint their faces and bodies this allows people to express themselves and the traditions of their community soil is also used in medicine a bacteria naturally found in soil is used to make antibiotics that treat infections [Music] soil is not just dirt it is an important natural resource that provides the foundation for life on Earth soil is made of rocks decayed plants and animals air and water soil comes from weathered rock that is broken down and moved through erosion there are three levels of soil topsoil subsoil and bedrock houmous gives soil nutrients and is part of the topsoil soil looks and feels different depending on its properties there are three types of soil sand silt and clay sand has the largest rock particles and feels gritty silt has medium sized particles and feels smooth clay has the smallest particles and feels sticky loam is a mixture of sand silt clay and houmous and is the best soil for growing plants farmers grow plants and topsoil soil holds roots in place and roots help with soil erosion worms make nutrient-rich castings they also create tunnels that allow air and water to reach below the surface soil is used in many ways including making homes for animals and people you [Music]

Channel: William Carroll Broome

Views: 297,493

Rating: 4.5466771 out of 5

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Id: I3A7OnTLSM8

Length: 12min 52sec (772 seconds)

Published: Tue Sep 27 2016