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Transcript of Soil
Leaching - the chemical weathering and erosion of substances by water.
It's not just for plants anymore.
* Copy this definition for soil: Soil
is a mixture of weathered rock, rock fragments, decayed organic material, air, and water.
Remember that organic material comes from living things. Soil gives a place for once living organisms to be recycled back into the environment.
Soil provides nutrients for plants, fungi, and bacteria, which ultimately provides food for all living things. Without soil, life would be almost impossible.
Five factors that influence the composition of soil:
is the material that is weathered to form soil.
This is the starting point of soil.
is the average weather conditions of an area.
The amount of rainfall affects the moisture in the soil and how minerals are dissolved in the soil. Rainfall tends to speed up weathering, so soils form quickly. However, it can also wash out nutrients in the soil.
is the shape of the land.
Steeper areas would have more erosion, so soils tend to be thin at the top of a hill and thick at the bottom; flat areas hold more water, so weathering can happen faster in those areas.
- the organisms that live in a area.
The organisms speed up the process of weathering, and they add to the organic matter when they decay.
- weathering is slow, continuous, so the soil experiences more and more breakdown over time. It can take up to 100 years to form topsoil.
are layers of soil that form due to the way soil weathers.
Label "Leaching and Leaching Lab" in lab notebook.
Water is necessary for life. Plants and animals use it, and it contributes to weathering. However, water has an affect on soil.
Water can weather the rock and decaying plants and animals to help form soil.
Water, also, washes nutrients and minerals from the topsoil down to the lower layers. This is called leaching.
leaching - The process by which rainwater dissolves and carries away nutrients in the top soil.
What processes make up leaching?
Chemical weathering (dissolving) and erosion (carrying the nutrients away) make up leaching.
The more water, the more leaching of nutrients.
What happens when water flows through top soil?
soil, coffee filter, funnel, red jello, water, beaker
1) place soil on coffee filter 2) Place filter in funnel and set on beaker. 3) Sprinkle jello powder on top of soil. 4) Slowly pour water through soil to see what happens.
(Write your observation.)
The Hydrologic Cycle
Leaching of nutrients through water erosion is just one problem that can reduce the fertility of soil; movement of soil through water or wind erosion is another.
Plants can help reduce soil erosion by anchoring the soil in place with their roots.
Here is a video showing how agricultural practices can benefit the land.
Unfortunately, plants can take nutrients out of the soil. Plants absorb nutrients and minerals from the soil in order to grow.
Crop rotation helps prevent nutrient depletion.
Horizon A - top layer that usually has organic matter. It us usually the darkest layer.
Horizon B - As rain/snow seeps into the soil, it carries some small particles such as clay, deeper into the ground.
Horizon C - contains material that has been weathered from bedrock below it.
Soils have various properties that are used to describe them.
Properties of soil:
- Red can mean iron, dark brown can indicate lots of organic matter.
- size of the pieces
- how particles hold together
- how it feels
- how fast water can enter the soil
- how much moisture it holds
- how acidic or basic soil is; This will determine the type of plants that grow in the soil
- the amount of nutrients/how well it supports life
- this changes daily
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