Soils + Minerals Nutrients

Soil Composition determines plants life in 4 ways:

1. Controls abiotic factors; temp + moisture.

2. Structure for anchorage.

3. Support microbial communities.

4. Contains nutrients needed for plant growth + development.

What are Essential elements?

Elements necessary for plant growth and reproduction.

What are beneficial elements?

Elements that might not be necessary but help the plant thrive.

What are macronutrients?

Required in relatively large quantities (more than 0.1% of dry biomass).

What are Micronutrients?

Required in small quantities (usually less than 0.01% of dry biomass).

What are the challenges of anion absorption?

• Potential differences generated by the proton gradient would keep anions out of the cell.

• H+ ions form complexes w anions, pulled via channels.

• Anions are not attracted to clay or organic acids, leach from soils.

What does the uptake of minerals across the plasma membrane involve and what do they do?

Proton pumps—use ATP to pump H+ outside the cell, generate potential difference.

Ion channels—open and close to regulate passage of specific ions.

As plants actively take up minerals, they get depleted from the rhizosphere and need to be replenished. How does this occur in 3 ways?

1. Bulk water flow due to transpiration— ions in solution move w the water.

2. Diffusion—ions move down their concentration gradient.

3. Root growth—uptake of water + minerals occurs just behind the root tip.

What is carbon essential for?

photosynthesis + forming organic molecules.

What is the function of nitrogen?

Structure of amino acids, proteins, + chlorophyll.

What is the role of calcium?

Very important for the middle lamella + developmental signaling.

What is Phosphorus’s function?

synthesize nucleic acids, phospholipids, and ATP.

What is the role of sulfer?

structure of amino acids.

What is the role of magnesium?

structure of chlorophyll, activation of some enzymes.

What is the role of Manganese?

The activation of photosynthetic enzyme.

What is the role of Chloride?

The activation of photosynthetic enzyme, osmotic solute.

What are the roles of boron, cobalt, copper and zinc?

Activation of some enzymes.

What are the signs of nutrient deficiency?

1. Stunted/slow growth

2. Chrlorosis (yellowing of leaves)

3. Necrosis—tissue death and poor fruit development.

What the Haber-bosch process?

Industrial process ammonia.

• nitrogen deficiency limited crop yield.

What does soil consist of?

organic, inorganic mineral matter, water, and air.

This depends on vegetation, soil compaction, and rainfall.

What does organic material consist of?

Humus— Dark colored, partially decayed matter w organic acids. Increases nutrient content, water retention, and aeration.

Inorganic mineral consists of rocks broken into particles of what different sizes?

• Sand —100um to 2mm

• Silt—2 to 100um

• Clay— less 2 um

What are the two groups soil can be divided into?

• Organic soils—formed from sedimentation, more than 30% organic matter.

  • form when organic matter is deposited more quickly than it is decomposed.

• Mineral soils—formed weathering of rocks, usually less than 30% organic matter.

  • weathering can occur via biological, physical, or chemical process.

The vertical section of soil is called soil profile and it’s by different zones called…?

Horizions

What is O Horizon?

the organic layer—dark in color, consists of partially decayed organic debris.

What is A horizon?

topsoil—mixture of organic and inorganic products; microbial activity; can be 2cm to over 1 meter.

What is B Horizon?

subsoil—present in older soils, dense layer of small particles w accumulated minerals.

What is C horizon?

Soil base—includes parent material (weathering to form the rest of the soil).

What is young soils?

Rich in minerals, containing all necessary nutrients.

• high concentration of ions in the solution can increase the osmotic effect and limit water movement into the plant.

• high concentrations of some elements can be toxic.

What are mature soils?

Lower concentration of nutrients, but they contain clays and organic material that can bind cations and release them as needed.

What pH do most plants grow well in soils

5.5 to 6.5

What do acidic conditions do?

• help increase proton concentration, freeing essential cations.

• help break rock down.

How does soil pH affect decomposition?

• Influencing microbial communities affect decomposition rates.

• Extremely acidic or alkaline conditions slow down decomposition, making nutrients less available.