Section 2 Flashcards
What are the main characteristics defining soil?
physical structure, chemical composition, association with plant roots or other resident organisms
Rhizosphere
soil that is in direct contact with living plant roots, secretions, and bulk soil
What is bulk soil?
soil that is located outside of the rhizosphere and is not penetrated by plant roots
What are the 4 main particle types of soil?
Sand, loam, silt, and clay
What is sand like?
large, coarse particles
What are silt and clay like?
fine particles that are more aerated
What are horizons?
the layers soil is divided into
What is the importance of horizon structure?
structure of horizons are a good predictor of nutritional characteristics of microbes living in them
What is the O layer?
Organic
undecomposed plant matter
What is the B layer?
Subsurface
lower levels of microbial life and more anaerobic bacteria
What is the A layer?
Surface
rich in organic matter and contains most soil life
What is the C layer?
Substratum
microbial life is low in abundance and is made up of inorganic matter
What is the R layer?
Bedrock
What is the significance of soil pH?
it is the best predictor of microbial diversity
Can soil be any pH?
No, it is in a specific range
What do microbes have to withstand?
Osmotic forces to facilitate the movement of ions
What are soil microbes?
microbes that live in the soil
What do soil microbes do?
they synthesize biochemicals used for bacterial warfare and they break down complex molecules
What are secondary metabolites?
organic compounds produced by bacteria that enhances their chances for survival
Are secondary metabolites essential for fundamental growth processes?
no
