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Ch. 14 Soils and Mineral Nutrition - Coggle Diagram
Ch. 14 Soils and Mineral Nutrition
Concepts
How plants get nutrients
Plants use their roots to absorb nutrients+ from the soil
how soil is formed
Rocks are broken down into soil. During soil formation rocks are converted gradually into dissolved ions and inorganic compounds
Soils contain large amounts of microbes and tiny animals that are extremely important to plants. This can supply plants with nitrogen which is not found in rock matrixes, When did their organic nitrogen Compounds are released to the soil and help the plants
Soils also supply minerals and harbor nitrogen fixing bacteria, but also in holding water, supplying air to roots, and acting as a matrix that stabilizes plants, preventing them from blowing over.
Mycorrhiza
- 90% of all species have roots that form a symbiotic association with soil fungi. The symbiosis permits plants to absorb phosphorus efficiently
Essential Elements
Hydroponic Solutions
- What scientist grow plants in so they can carefully control the chemical composition
Hydroponic Experiments were formalized and used extensively by Julius Von Sachs (1860) First this was very trial and error to see if the plant survived certain solutions
Once a solution was found to support growth they would vary a single element in supply to the plant. If an element is left out and it still grows the same and that it was not essential for plant growth
Types of elements
Essential elements
- discovered by Sachs and needed for plant growth. Also called the
major
and
macro essential elements
because they're needed in large quantities by plants.
Iron is neither a macro nor micro essential element. It is intermediate of the two.
trace elements
or
minor
/
micro essential elements
which are required in extremely low concentrations by plants.
Immobile elements
- Elements that once they have been incorporated into plant tissue they remain in place
Mobile elements
- Even after the element has been incorporated into a tissue it can be translocated to younger tissue. If the soil becomes exhausted of one of these elements the plant will sacrifice older leaves to save younger ones
An element must meet 3 basic criteria to be considered essential
The element must be necessary for complete, normal plant development through full life cycle
The element itself must be necessary, and no substitute can be effective
The element must be acting within the plant, not outside it
Mineral and Deficiency Diseases
Virtually all types of soil contain at least small amounts of all essential elements. It is written counter points his growth and development are seriously disrupted by scarcity or an excess of mineral elements.
Desert soil's often have excessive Amounts of all available minerals because ground water moves upward curing salt minerals with it.
Some plants absorb both water and salt but personal directly through the body and secreted from salt glands located on their leaves. This produces a coating of salt crystals that is thought to be selectively advantageous as it deters desert animals from eating them due to the high salt content from the crystals
Not common in natural populations. Plants adapt to soil deficiencies and those can't/don't, become weak or die and don't reproduce very well.
Symptoms
Chlorosis
- leaves lack chlorophyll, tend to be yellowish and are often brittle and papery
Deficiencies of nitrogen or phosphorus caused the accumulation of anthocyanin pigments which gave the leaves either a dark color or a purple hue
Necrosis
- The death of patches of tissue (necrosis can also be caused by bacterial, viral, and fungal infections).
Soils and mineral availability
Weathering
- the breaking down of rocks, soils, and minerals as well as wood and artificial materials through contact with the Earth's atmosphere, water, and biological organisms
Has 2 fundamental processes
Physical weathering
- breakdown of rock By physical forces such as wind, water movement, and temperature changes.
Coarse sand- the largest size of soil particles, cause by phys. weath.
Next in size are fine sand. Silt is even smaller than fine sand. Next are clay particles also known as micelles
The various particle sizes affects all texture and porosity
Chemical weathering
- Involves chemical reactions, and the most important agents are acids produced by decaying bodies, especially those of plants and fungi. Also the secretion of acids from organisms while alive in the carbon dioxide produced during respiration formed with water forming carbonic acid
Decreasing soil particle size and alters soil chemistry
Soil pH affects the chemical form of certain elements causing them to change solubility.
Many factors affect soil acidity such as the chemical nature of the original rock, but probably the most important factor is rainfall.
Acid rain- Sulfur dioxide reacts with water to form sulfuric acid, which then dissolves into the water droplets of clouds
Cations are loosely bound to micelle due to their charge. Since roots cannot absorb them directly they must be first freely dissolved into the soil solution this is done by
cation exchange
-
Nitrogen metabolism
Nitrogen does not occur as a component of rock matrixes nor is a contaminant and rocks the most abundant source of nitrogen is the atmospheric gas N2
Consists of
1) nitrogen fixation- The conversion of gas into nitrate, nitrate, or ammonium
2) Nitrogen reduction- The process of reducing nitrogen in the nitrate ion from an oxidation state of +5 to the -3 oxidation state of ammonium, which is also the oxidation state of nitrogen in amino acids, nucleic acid's, and many other biological compounds
3) Nitrogen assimilation- The actual incorporation of ammonium into organic molecules in the plant body.
The transfer of an amino group from one molecule to another is transamination
Nitrification
Certain soil bacteria or nitrifying bacteria: the oxidize ammonium to nitrate and others oxidize nitrite to nitrate.
Obtaining nitrogen from animals
Carnivorous plants obtain their energy through photosynthesis, not from the fats, carbohydrates, or proteins of the animals they consume
Ant-plants
-Are flowering plants and ferns are also contain reduced nitrogen from animals
Storage of minerals within plants
It is crucial for plants to be able to store minerals because they will not always be available in appropriate quantities throughout their lives
All parts of the plant except for seed store minerals in soluble form in the central vacuole's of cells.
In seeds amino acids are stored as particles of proteins so tightly packed that it typically crystallizes into a structure called a protein body.
Nitrogen can be concentrated a little by being converted to compounds with multiple amino group such asparagine, etc
This method does not permit storage with large amounts of minerals because high concentrations would be toxic
