Exam #1 Flashcards
what is soil made of?
45% minerals
25% air
25% water
5% organic matter
an average soil is composed of ____ pore space found between particles
50%
what are the five plant growth factors?
light, temperature, water, nutrients, and genetics
define “soil”
the material; mixture of minerals, gases, water, organic matter, and organisms capable of supporting plant life
define “a soil”
an individual natural body (organized, 3-dimensional, region/biome specific, and has distinct characteristics.
define “the soil”
all of the soils (natural bodies). soil the material, roots, ground dwelling animals and rocks.
the soil (all of the soils) is also called the ______
pedosphere
what are the four spheres of the pedosphere? (spheres are always intertwined)
1) atmosphere/soil air (CO2, O2 and N2)
2) biosphere/organic matter and biomass (plants, animals, microbes)
3) hydrosphere/soil water (water and dissolved substances)
4) lithosphere/soil particles (minerals in rocks, clay and sediments)
soils have layers called what?
horizons (O horizon, A horizon, B horizon, C horizon and bedrock)
how long does it take for 1 in of topsoil to form?
500-1000 years
soil quality is determined by its capacity to….
provide ecosystem services
what are ecosystem services?
products and functions of natural systems that support and fulfill the needs of humans
what are the six ecosystem services provided by soils?
1) plant medium growth (nutrients, physical support, root aeration, moisture supply and storage, temperature regulation, and protection from toxins)
2) provides and recycles nutrients (mineral weathering releases nutrients from unavailable storage forms)
3) regulates the atmosphere (huge carbon pool or sink)
4) provides hidden habitat (bacteria, fungi, insects, earthworms, etc)
5) serves as an engineering medium (building infrastructure)
6) nature’s rain barrel (storage) and water filter
is soil a renewable or a non-renewable resource?
non-renewable
what is soil degradation?
reduction is soil quality
what are the causes of soil degradation?
erosion, nutrient depletion, organic matter depletion, compaction, acidification, and salt accumulation
what percentage of soils have been degraded?
33% of global soils
soil restoration is key to _______
agroecosystem restoration
where does soil form?
Earth’s crust, upper lithosphere (and uppermost solid mantle)
what is the critical zone?
top of tree canopy to the water table
soil is the heart of the _______ _____
critical zone
Igneous rocks forms…
during cooling and crystallization of lava or magma
Sedimentary rocks forms…
from cementation (lithification) of sediments (small rock fragments)
Metamorphic rocks forms…
when igneous or sedimentary rocks are altered under high heat and pressure conditions found deep in Earth’s crust