Plant Nutrition and Soil Biology

Plant Nutrition and Soil

• Approximately 95% of a plant's dry weight consists of carbon, hydrogen, and oxygen.
• These elements serve as fundamental components for compounds like carbohydrates.
• Carbon dioxide and water function as primary nutrients.
  • Carbon dioxide provides carbon, while water supplies hydrogen and oxygen.
• Minerals are inorganic substances that generally have a combination of at least two elements.
• Nutrients are essential when they have an identifiable role, cannot be substituted by another nutrient, and deficiency in that nutrient causes the plant to die.
• Macronutrients: C, H, O, P, K, S, Ca, Mg
• Micronutrients: Fe, B, Mn, Cu, Zn, Cl, Mo
• Hydroponics is a method that enables plants to grow when they are supplied with the essential nutrients.
• Plants can thrive when given sunlight, water, and minerals.
• Observed growth effects of omitting specific nutrients tested for deficiency effects.
• Farmers and Gardeners routinely use fertilizer to prevent deficiencies.
• The NPK ratio represents the percentage by weight of nitrogen, phosphorus, and potassium within a fertilizer.
• Soil is composed of mineral particles, organic material that is decaying, living organisms, as well as air and water.
• Soil facilitates plant development.

Soil Formation

• Occurs when rock begins to weather
  • Weathering can be mechanical with wind, rain, or ice, or chemical with lichen or moss.
• Organisms are very important to soil creation.
  • Lichens and Mosses
• Humus constitutes decaying organic matter.
• Classifying Soil Particles: sand, silt, and clay
  • Sand particles are larger, ranging from 0.05 to 2.0 mm.
  • Water flows through sand readily.
  • Silt particles range from 0.002 to 0.05 mm.
  • Clay particles measure less than 0.002 mm.
  • Clay has many tiny spaces that are filled with water.
• Loam soil yields a mix of aeration and minerals due to sand, silt and clay.
• Balanced soil needs clay particles and humus. Humus boosts soil quality.
• Concentrations of 10 to 20% Humus are ideal.
• Decreases runoff, and inhibits leaching.
• Makes the soil more acidic and retains charged minerals.
• Bacteria and fungi breakdown organic matter to return it to plants. Living organisms support soil composition
• Small plants support soil development from rock.
• Large plants become dominant in succession systems.
  • Roots perforate into bedrock, making way for water, air.
• Soil-dwelling burrowing animals assist soil by burrowing.
• Earthworms create worm casts for aeration.
• Ants aerate soil and build colonies.
• Microorganisms support decomposition of humus.
  • Soil bacteria enrich nitrogen for accessible plant uptake.
• Negatively charged clay and humus connect to positively charged minerals: calcium and potassium.
  • Action prevents leaching

Cation Exchange

• Process which positive ions trade positions with positively charged minerals
  • Allows the roots to absorb nutrients.
• Cation exchange capacity (CEC) represents negative charge site availability to bind positive cations.
  • Sandy soils' CEC is lower than those with clay and humus.
• Soil profiles represent a vertical segment from ground level to bedrock underneath.
  • Soil Horizons create layers
    • A (topsoil) makes up litter and humus
    • B (subsoil) has inorganic nutrients
    • C has weathered rock
• Given parent material, a soil profile may change according to climate conditions.
• Soil erosion happens as wind and water remove soil to a new location.
  • Approxmiately 40% of worldwide farmland gets seriously degraded.
  • Areas of lands are equal to Texas are lost per year.
• Inappropriate land management causes erosion.
  • Deforestation is tree loss.
  • Desertification is the increase in deserts due to farming on unproductive land.
• Crop rotation can mitigate erosion.
• Reduced tillage and companion crops assist practices to lower erosion.
• Coastal erosion has formed the state of California.
  • Wooded and trees serve as critical counter measures that inhibit erosion from occuring along shore lines.

Water and Mineral Uptake

• Mineral and water are absorbed through plant roots by the same pathway.
  • Porus cell walls are needed to enter endodermal cells by the casparian strip.
  • Root hairs across the cortex and endodermis leverage cytoplasmic cells within cells.
• Water moves into root cells as osmotic pressure decreases down into the soil.
• Trace minerals get absorbed into the xylem in water.
• Plants absorb minerals through transport.
• Plant cells utilize energy to take up ions.
• The Casparian strip assists in protecting from backflow and allows concentrations.
  • Roots use the ability to concentrate approxmiately 10,000 greater minerals.
• Plasma-membrane proton pumps carry hydrogen ions towards the exterior of the cell.
• Electrochemical gradients force charged ions in cells.
• Charged mineral ions are carried with carrier proteins.
• No energy gets required from moving down the concentration gradient.
• This model is named chemiosmosis, the process occurs when electrochemicals are cells in the working process.
• Next minerals transverse through the leaves.
• Roots adapt for mineral uptake through symbiotic relationships, such as through rhizobium bacteria within root nodues.
  • Root nodules produce atmospheric nitrogen
  • Host plant provides the bacteria with carbohydrates.
• Mycorrhizal associations occur between fungi and plant roots
  • Fungi heighten the surface area for mineral, water, helping decomposition.
  • The origin supplies amino acids and sugar.
• Parasitic and Carnivorous plants

Transport Mechanisms in Plants

• Nutrients and waters transfer through vascular tissue.
• Minerals and waters are delivered through the xylem.
  • Tracheids and vessel elements are types of conducting cells
  • Waters moves passively towards regions of high to that low.
• Organic substances move through phloem.
  • Sieve-tube members contain conducting cells.
  • Companion cells create protein content
  • End walls turn to sieve plates
  • Plasmodesmata increase sieve plates.
• Xylem and phloem are responsible for transmitting parallel cells to move water via carbohydrates through plant origins.
• Water shifts via the xylem from the downward direction to the upper side of the plant;
• Sucrose materials move via phloem
• Potential energy is stored energy.
• Water potential measures the energy of water, shifting passively from places of regions of maximum potential towards reduction of water.
• Term of cells:
  • Water pressure shifts for the membrane
  • Solute concentration for membrane
• Effect of water occurs with pressure potential.
• Transfer membrane occurs from high to low, having higher water potential
• Osmosis increases to make turgor pressure
• Solutes determine osmotic potential
• Water tends to proceed towards the area of higher concentration.
• As concentration decreases to cause high water pressure.
• When leaves need pressure at the xylem, it forms pipeline with vessel elements
• Perforated plates determine water transport, as guttation water transports along edges.
• The passive xylem transfers via cohesion-tension,
  • As water molcules have a tendency to cling.
  • Vessels help molecules interact.
• Waters move upward through transpiration .
• Tensions occur as leaves release water tension.
• Epidermis borders on the leaf by guard cells.
  • Turgor pressure assist guard cells in increasing
  • Active transport enables as osmosis, openings cause potassium movement and abscisic closes
• The sugary material is transported with the phloem, sugar travels from origin, causing girding and accumulates to form a sweet tissue.
• Studies affirm nutrients transfer, and sugary contents are available.