ODWS icon

The Open Door Web Site
HOMEPAGE CHEMISTRY PHYSICS ELECTRONICS HISTORY HISTORY OF SCI & TECH MATH STUDIES LEARNING FRENCH STUDY GUIDE  PHOTO GALLERY
BIOLOGY HOMEPAGE  IB BIOLOGY WEB TOPIC CHAPTERS FACTS & FIGURES LABORATORY WORK QUESTIONS & QUIZZES ECOLOGY CLUB PLAYS

 

Part X : The Environment

Environmental Factors Appropriate for Life :
Associated Practical Work

Environmental Factors Appropriate for Life : Question

Environmental Factors Appropriate for Life
What is soil made of?
Life in the Soil
Environment and Distribution
Water
The Water Cycle
The Globe and the Water Cycle
The Seasons
The Seasons and the Sun
How Seasons Influence the Biosphere
Human Influences on the Environment

Topic Chapters Index

 

Diagram to show decomposition of soil © Paul Billiet

 

Leaf litter on a deciduous forest floor  © Shirley Burchill

Leaf litter on a deciduous forest floor © Shirley Burchill

SOIL

Custom Search

Soil is found wherever plants grow. Plants need soil for growth because the soil gives them not only water but also minerals, such as calcium or iron. Plants help to make soil. When plants die or drop their leaves they decompose and add organic matter to the soil. Organic matter helps to hold the soil together; it makes the soil moist' without being too wet and it makes the soil very fertile.

The roots of plants help to hold the soil and stop it from being washed or blown away.

 

Fact File No.40

Scientists use the word 'organic' to describe material which is made by a living organism.

 

Water erosion has caused the roots of this tree to be exposed, Sheffield, UK © Shirley Burchill

Water erosion has caused the roots of this tree to be exposed, Sheffield, UK © Shirley Burchill

 

Soil normally contains three types of particles; sand, silt and clay. Sand particles are quite large, between 0,5mm and 0,05mm in diameter. If there is too much sand in the soil water will drain through the soil too quickly. This will mean that plant roots will not have enough time to absorb the water.

Clay is made of much smaller particles, below 0,002mm in diameter. Too much clay in the soil will not allow water to drain through it very well. This means that plant roots could lack oxygen. Silt particles are between 0,05mm and 0,002mm in diameter.

Soil needs to be a mixture of all three types of particles. It must also contain humus. Humus is what is left of the organic material, such as dead leaves, which is broken down by decomposer organisms. When humus is mixed with clay, soil crumbs are formed. Soil crumbs are rich in minerals and they improve the drainage of the soil. Soil crumbs also allow more air to circulate through the soil.

A soil which contains a mixture of sand, silt, clay and humus is called loam. Loam is a fertile soil, providing plants roots with water, air and minerals.

 

The Open Door Web Site is non-profit making. Your donations help towards the cost of maintaining this free service on-line.

Donate to the Open Door Web Site using PayPal

SITE MAP
WHAT'S NEW?
ABOUT

PRIVACY

COPYRIGHT

SPONSORSHIP

DONATIONS

ADVERTISING

© The Open Door Team 2017
Any questions or problems regarding this site should be addressed to the webmaster

© Paul Billiet, Shirley Burchill, Alan Damon and Deborah James 2017

Hosted By
Web Hosting by HostCentric


SiteLock