Exam #1-HORT-120 Flashcards
Describe the two factors of nutrient availability
- Availability depends on soil pH
- Availability depends on texture
Briefly explain how nutrient availability is dependent on texture
Finer soils retain more nutrients than coarse soils.
briefly describe Soil Tilth
soil tilth is the suitability of soil to grow plants.
soil texture
soil texture is the size of soil particles
soil structure
soil structure is how the particles fit together
pore space
pore space is the amount of space between the soil particles for water and air to pass through. Increasing organic matter = increasing pore space.
describe soil pH
pH is how basic or acidic the soil is, pH=6 > pH 7
slightly acidic > Neutral
what gives soil its characteristics?
water, porosity, plants and roots, animals, humans and their machinery, fungi.
what are the four soil forming processes?
- additions- putting something in
- subtractions- taking something out
- translocations- within the profile moved from one place to another.
- transformations- changing form (decomp)
what are the five Soil State factors?
the five soil state factors are:
1. Climate
2. Topography
3. Organisms
4. Parent material
5. Time
How does climate affect soils?
Wind, precipitation, sun exposure, freeze/thaw, and temperature changes (especially heat), can alter chemical reactions in soil and the rate of said reactions and decomposition.
What is Topography?
where something is located in terms of mountains, valleys, slope and elevation etc.
what are soil horizons?
layers of soil- O, A, B, C, R
What is “soil orders”
soil orders are the distinct horizon combinations, there are 12.
What is Michigan’s state soil?
Kalkaska sand- a spodsoi. the sand layers range from yellow to red to black.
What does Tillage do to soil structure? (positive)
- promotes aggregation
- allows root penetration (aeration)
- compaction to allow imbibing
-incorporates organic matter
What does Tillage do to soil? (negative)
- destroys aggregation (releasing carbon)
-reduces airspace (increase compaction)
-speed up loss of organic matter
What is soil made of?
soil is made of minerals, organic matter, water, air and gases, and organisms.
What is a mineral?
A Mineral is a substance found in soil that is inorganic, but naturally formed.
Primary minerals
primary minerals are rocks formed at HIGH TEMPS: from igneous and metamorphic rock.
Secondary minerals
Secondary minerals are rocks formed at LOW TEMPS: from sedimentary rocks/weathering
what are the three mineral groups?
- Aluminosilicates
- Oxides (magnesium, iron)
- Minerals made from organic matter (mostly plant material).
All ( ) is organic matter, but not all ( ) is humus.
Humus, organic matter.
briefly describe Humus Organic Matter
Humus organic matter is brown/black material that results from decomposition
what effects the rate of decomposition?
pH, Temperature, Climate, and the composition of organic matter.
What are the two types of Humus?
- Active
- Passive
Describe Active Humus
active humus adds nutrients, not structure, so it is still decomposing.
Describe Passive Humus
passive humus adds structure, not nutrients so it is done decomposing.
Mineralization
Mineralization is a process that changes ORGANIC particles into INORGANIC end products.
.
.
Briefly describe Topsoil
Topsoil is the top 2-8 inches of soil, it is high in organic matter and nutrients. Topsoil is where the biological activity occurs, plant roots are typically found in the topsoil and topsoil varies by geography.
Nitrogen Fixation
Nitrogen fixation occurs when bacteria convert nitrogen gas into organic compounds that living organisms can take up.
Ammoniafication
ammonification occurs when bacteria or fungi convert nitrogen gas/compounds into ammonia ions.
Nitrification
nitrification is a two-step process where soil bacteria first convert ammonia ions into nitrite ions, and then converts nitrite ions into nitrate ions.
Denitrification
dentification occurs when soil bacteria convert nitrate ions into nitrogen gas.
Assimilation
assimilation occurs when organisms take up nitrogen.
Earth is a ( ) system
closed, meaning all the elements we have are all that is available.
define Biogeochemical cycles
Biogeochemical cycles are our planetary recycling system that allows for the constant regeneration of living things and geologic structures.
What is a geochemical process?
geochemical cycles are SPONTANEOUS processes involving INORGANIC components of the earth, they will happen whenever the right reagents come together under the right conditions.
What is a biological process?
biological processes are driven or influenced by life: bacteria, fungi, plants and animals. * requires a living organism *
Briefly describe Carbon and where it is found.
Carbon is the building block of life, it is dissolved in the atmosphere, dissolved in water, stored in fossil fuel reserves, in rock (primarily limestone), and organisms.
Briefly describe Nitrogen and where it is found.
Nitrogen is a key component of proteins and DNA. nitrogen is dissolved in the atmosphere, is in plants and animals, and is a limiting nutrient in most environments.
Briefly describe Phosphorus and where it is found.
Phosphorus is a key component of DNA and energy storage/exchange. Phosphorus is in soil and rock, in the deep ocean floor, in plants and animals, and is a limiting nutrient in most environments.
Briefly describe Potassium and where it can be found.
Potassium regulates the signaling and movement of water and nutrients within cells and organisms.
> It is found in soil, rock, AND plants and animals. >Potassium is also easily lost to erosion and runoff.
what are the main processes of the Carbon Cycle
Photosynthesis, respiration, combustion, diffusion, mineralization, sequestration.
What are the main processes of the Nitrogen cycle?
fixation, nitrification, denitrification, assimilation, ammonification, runoff/leaching.
What are the main processes of the Phosphorus cycle?
- Extraction: mining for phosphorus.
- Runoff/leaching
- Mineralization
- Uptake by plants.
What are the main processes of the Potassium Cycle?
- Uptake
- Exchange (dynamic equilibrium)
- leaching/runoff
- Extraction: mining
Describe Exchange in the Potassium cycle.
It is the back and fourth of potassium between solution K ( what plants can use) and fixed K.
Explain Nutrient Recycling
A plant dies > organisms break down the dead plant> nutrients from broken down material help plants grow.
What effects soil organisms?
Climate, water, heat, weather patterns, pH, chemistry, plant cover.
Name the four Soil community interactions.
- competition -/-
- parasitism +/-
- commensalism +/0
- mutualism +/+
Name some macroorganisms (engineers)
herbivores, detrivores, predators
Name some Microorganisms (process controllers)
Detrivores, predators, parasites, mites, nematodes. 80% of soil activity is due to microorganisms.
What benefits do bacteria have on soils?
They release nutrients, they make and release plant hormones, improve structure of soil, clean up the soil.
Bacteria complete nitrogen fixation, what does this mean?
Bacteria puts nitrogen into a form that plants can use such as ammonia, nitrates and nitrites.
Briefly describe Mycorrhizal fungi and its relationship with plants.
Mycorrhizal fungi is a network of filaments that work with plant roots to draw nutrients from the soil that the root system would not be able to uptake on its own.
What is a nematode?
Nematodes are soil organisms that can be used as effective soil health bioindicators because they are adapted to almost every ecosystem
Describe a dynamic equilibrium
Atmospheric and aqueous carbon dioxide exist in a dynamic equilibrium; when the rate of the forward reaction is equal to the rate of the reverse reaction.
What is Sedimentation?
When phosphorus-containing organisms/compounds sink to the ocean floor, they form sedimentary layers.
What is the endpoint for the phosphorus cycle?
Deadfall- phosphorus permanently trapped on the deep ocean floor.
Name the processes of the water cycle
- Evaporation: surface water to air
- Condensation: air to cloud formation
- Transportations: clouds moving
- Precipitation: air to surface water (rain or snow)
- Runoff: surface water movement along the ground
- Infiltration: surface water movement to soil
- Percolation movement through the soil into groundwater aquifers
- Evapotranspiration: movement through plants from groundwater/soil into air.
- Sublimation: snow/ice to air (without melting)
- Deposition: compaction of snow/ice into glacier.
Define sequestration
Sequestration is the process of capturing, securing, and storing carbon dioxide from the atmosphere.
Define Bulk Density
Bulk density is the dry weight of a specific volume of soil, how dense the soil is. Adding organic matter = decrease in Bulk density.
What is the oxygen diffusion rate in soil?
How fast can oxygen be replenished in the soil depends on diffusion or fresh air into the soil and pore space!!
Increased organic matter = increase the O2 diffusion rate
Describe Field capacity
Field capacity is the amount of water held in a field that has been allowed to drain for 24 hours.
> Low FC means the water runs off too quickly.
> High Fc means the water stays too long
What makes soils unique?
Their physical, chemical, and biological properties
How are Soil organisms involved in nearly
every aspect of soil quality?
Structure/aggregation, organic matter, decomposition, nutrient recycling, nitrate leaching, and humus formation are all affected by soil organisms.
Ectomycorrhizae
outside of the root, hyphae do not penetrate cells.
Endomycorrhizae
Inside the root, hyphae penetrate root cells, far more common.
