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3 requirements to be an essential element
- required for completion of life cycle
- not replaceable by another element
- directly involved in plant metabolism
how many essential elements exist?
how many categories of essential elements exist?
- essential non-mineral elements
- primary nutrients/fertilizer elements
- secondary nutrients
what are the essential non-mineral elements
- Carbon (C)
- Oxygen (O)
- Hydrogen (H)
Why are non-mineral elements considered non-minerals?
they are gasses
What are the primary nutrients/fertilizer elements?
- Nitrogen (N)
- Phosphorus (P)
- Potassium (K)
What is speical about fertilizer elements?
needed in greater amounts by plants and added to soil through fertilizer
What are the secondary nutrients?
- Calcium (Ca)
- Magnesium (Mg)
- Sulfur (S)
What is special about secondary nutrients?
needed by plants in lesser amounts than primary nutrients
What are the micronutrients?
- Boron (B)
- Iron (Fe)
- Manganese (Mn)
- Copper (Cu)
- Zing (Zn)
- Molybdenum (Mo)
- Chlorine (Cl)
- Nickel (N)
What is special about micronutrients?
they are needed in the smallest amounts by plants
What are beneficial elements?
elements that promote plant growth but are not absolutely necessary for completion of life cycle
What are the beneficial elements?
- Silicon (Si)
- Sodium (Na)
- Cobalt (Co)
- Selenium (Se)
What are mobile elements?
elements that can be translocated from one part of the plant to another after they've been absorbed in plant tissue
When there is a deficiency of mobile elements, where does it show up?
in older leaves
What are immobile elements?
elements that can't be translocated from one part to another after being absorbed into plant tissue
When there is a deficiency of immobile elements, where does it show up?
younger leaves first
Soil is the...
most basic natural resource in agriculture
influence crop adaptation
extreme variations exist in........of soil.
both physical and chemical properties
properties of soil determine
if a crop can be grown successfully
What are soils composed of?
pore spaces and solid materials in varying proportions
Pore spaces contain
air and water in relative quantities depending on pore size and weather
What types of pores are there?
non-capillary pores are
larger pores that contain air except immediately after periods of rainfall
capillary pores are
smaller pores that hold water against the force of gravity for plant use
plants require what for optimum growth?
capillary and non-capillary pores need to exist in soil in
near equal volumes
solid portions of the soil contain
what is organic matter?
plant and animal residues in all stages of decomposition
organic matter represents how much mineral top soil by weight?
what does organic matter contribute to the soil?
highly desirable physical, chemical and biotic qualities
soil make up is divided into 3 categories based on
What are the 3 categories of make up?
- sand (large)
- silt (intermediate)
- clay (smallest)
what is a soil texture triangle?
used to determine texture of a soil
What does soil texture triangle do?
shows the relative proportions of particles
What is soil structure?
the arrangement of soil particles
the most desirable type of aggregation of soil separates are
moist soil crumb/granular structures crumble when
they are tilled or handled
what are the advantages of crumb/granular soil structure?
- plant root growth
- water movement
- tillage case
what is soil reaction
the measure of the degree of acidity or alkalinity of soil
soil reaction is expressed as a
pH or the potential of hydrogen/hydrogen ions
soil reaction affects the
availability of nutrients for plant uptake
most crops perform best when soils are
slightly acidic to neutral
a neutral pH would be
acidic soils have a pH of
greather than 7.0
alkaline soils have a pH of
less than 7.0