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___ is the substrate on which plants depend.
Three main components of topsoil:
- 1. mineral particles (inorganic compounds)
- 2. Living organisms (break down and recycle organic debris)
- 3. humus (partially decayed organic material)
What are the 4 layers of soil, top down?
- 1. Leaf litter and plant life
- 2. topsoil
- 3. subsoil
- 4. bedrock
Most roots are found in which layer of soil?
____ is characterized by relative amounts of sand, silt, and clay.
____ binds water and nutrients minimally while ____ binds water and nutrients very tightly.
Soil particles tend to have a (positive/negative) charge.
Negative charge (-)
(Positive/Negative) ions are attracted to soil particles. (Positive/Negative) ions stay in solution around roots.
- positive (+) ions attracted to soil
- negative (-) ions stay in solution
Because of the charge gradient between the soil and roots, _____ ____ is required to acquire and maintain K+ and other positive ions in the root.
A balance of ____ and ___ in the soil is essential for root growth.
A balance of air and water
What fills the pores among soil articles?
Water and air
_________ can result in soil loss and nutrition depletion.
What are 4 causes of soil loss and nutrient depletion?
- poor landscaping
- poor farming practices
- drought ("Dust Bowl" in 1930's)
Up to _________ tons of topsoil have been lost from fields in the U.S. in a single year.
50 Billions tons of topsoil!
Give 4 solutions to combat erosion...
- Mixing crops in a field
- Conservation tillage
- No-till practices (not plowing under fall crop detritus)
- Minimize runoff of fertilizers from farm, lawns, and gardens into waterways that result in algal blooms.
Fertilizer runoff from farms, lawns, and gardens into waterways results in what?
What two factors affect water and mineral availability?
pH and salinity
Acidic soil releases ___ from rocks. Why is this harmful?
- Aluminum is toxic to plants and may combine with other nutrients making them unavailable to plants
What happens in salt soils?
Salt soils draw water out of plants causing them to lose turgor pressure.
Plants require ___ macronutrients and ___ micronutrients.
Name the 9 macronutrients required by plants (CHNOPSCM)...
Carbon, hydrogen, oxygen, nitrogen, potassium, phosphorus, sulfur, calcium, and magnesium.
Name the 8 micronutrients required by plants (BIZCCMMN):
Boron, Iron, Zinc, Chlorine, Copper, Manganese, Molybdenum, Nickel
Food security is related to crop _____ and ____ levels.
crop productivity and nutrient levels
Some goals of plant breeding involve doing what to the nutrient levels in food crops while they are growing in the field?
Increasing nutrient levels
True or false: Fungus living in close association with roots can provide nitrogen.
False! Bacteria living in close association with roots can provide nitrogen.
Give an example of a plant living in a symbiotic relationship with bacteria.
Legumes have a symbiotic relationship with bacteria living in the nodules of their roots.
_______ aid a large portion of terrestrial plants. More than 90% of plants have a symbiotic relationship with "_____ ______"
- "Fungus roots"
Where are carnivorous plants usually found?
Usually found living in acidic, nitrogen-poor environments.
True or false: All parasitic plants are photosynthetic.
False. Some are, but some are not.
Mistletoe is a type of ____ plant that taps into a host plant to obtain nutrients, including carbohydrates.
Elevated CO2 levels can do what to plants?
Alter photosynthesis and carbon levels
An increase in CO2 results in an (increase/decrease) in photosynthesis. This, in turn, results in an _______ in biomass.
The plant tissue produces by a plant with higher levels of CO2, has a higher proportion of carbon compared to _____, resulting in a shift toward more carbohydrate and less _____.
- More carbohydrate and less protein
What happens when there is less protein available in plants?
- Herbivores must eat more plants to get the same amount of nutrients.
- Greater plant loss to herbivory
Elevated temperature can affect ____ and ____ in plants.
Respiration and carbon levels
The higher the temperature, the greater the rate of ____ in plants.
What does plant respiration do?
Plant respiration breaks down carbohydrates and can result in changes in plant nutrient balance.
use of plants to remove toxic contaminates from the soil or water
Poplar trees remove ________ from the soil and convert it to CO2 and chlorine compounds.
_____ trees remove trichloroethylene from the soil and convert it into ____ and ____ compounds.
- Poplar trees
- CO2 and Chlorine
Some plants can remove small amounts of ______ in the soil and degrade it.
How are plants used to remove heavy metals from the soil?
Contaminates accumulate in shoots of plants and then the plants are removed.