Soil and Plant Nutrition

  1. Fragile Ecosystem
    • upper layers provide nutrients and water to plants
    • Plants, bacteria, insects, fungi, nematodes live in and create structures of soil
  2. Soil Stratification
    • -layers known as horizons
    • -upper layer is topsoil
  3. Name soil particles from smallest to largest (3)
    • clay
    • silt
    • sand
  4. what does topsoil consist of
    • mineral particles
    • living organisms
    • decaying organic material
  5. Loams
    soils that support highly productive plant growth composed of roughly equal parts sand, silt, and clay
  6. cations adhere to?
    negatively charged soil particles
  7. what happens during cation exchange?
    • cations are displaced from soil particles by other cations
    • Displaced cations enter the soil solution and can be taken up by plant roots
    • Negatively charged ions do not bind with soil particles and can be lost from the soil by leaching
    • •Percolating groundwater
  8. how does agriculture impact soil
    • Depletes nutrients
    • –Increases erosion
    • –Taxes water resources
    • –Soil compaction
    • –Alters soil communities
  9. Aquafiers
    primary source of irrigation water is in these underground water reserves
  10. the depleting of aquifiers can result in?
    subsidence- the settling or sinking of land
  11. salinization
    • concentration of salts in soil as water evaporates
    • irrigation can lead to this
  12. Fertilization replaces what?
    mineral nutrients that have been lost from the soil
  13. commercial fertilizers are enriched in?
    • nitrogen
    • phosphorus
    • potassium
  14. organic fertilizers are composed of?
    • manure
    • fishmeal
    • compost
  15. Large monoculture farms with high fertilizers have?
    bacteria dominated soil food webs
  16. natural systems and organic farms have?
    fungal based soil food webs
  17. what does erosion of soil cause?
    loss of nutrients
  18. how can erosion be reduced
    • –Planting trees as windbreaks
    • –Terracing hillside crops
    • –Cultivating in a contour pattern
    • –Practicing no-till agriculture
  19. when is a chemical element considered an element?
    if it is required for a plant to complete its life cycle
  20. Macronutrients
    • 9 essential elements
    • -plants require them in large amounts
    • Carbon
    • Oxygen
    • Hydrogen
    • Nitrogen
    • Phosphorus
    • Sulfur
    • Potassium
    • Calcium
    • Magnesium
  21. Micronutrients
    • 8 elements
    • plants need them in small amounts
    • Chlorine 
    • Iron
    • Manganese
    • Boron
    • Zinc
    • Copper
    • Nickle
    • Molybdenum
  22. Rhizosphere
    • •The layer of soil bound to the plant’s roots
    • •The rhizosphere has high microbial activity because of sugars, amino acids, and organic acids secreted by roots
  23. Rhizobacteria
    • •Free-living
    • •Function in the rhizosphere
    • •Can enter roots
  24. what can rhizobacteria do
    • –Produce hormones that stimulate plant growth
    • –Produce antibiotics that protect roots from disease
    • –Absorb toxic metals
    • –Make nutrients more available to roots
    • •Inoculation of seeds with rhizobacteria can increase crop yields
  25. Nitrogen cycle
    transforms nitrogen and nitrogen-containing compounds
  26. where does most soil nitrogen come from?
    • actions of soil bacteria
    • nitrogen can be an important limiting nutrient for plant growth
  27. what do plants absorb nitrogen as?
    either NO3– or NH4+
  28. Nitrification
    carried out by bacteria that convert NH3 into NO3–
  29. Nitrogen fixation
    conversion of nitrogen from N2 to NH3 through nitrogen- fixing bacteria because plants cannot directly take in the N2 from the atmosphere
  30. plants in legume family have what with nitrogen fixing bacteria
    a symbiotic relationship
  31. nodules
    • swellings along legume's roots, composed of plant cells infected by nitrogen fixing rhizobium bacteria
    • The bacteria of a root nodule obtain sugar from the plant and supply the plant with fixed nitrogen
  32. bacteroids
    Inside the root nodule, Rhizobium bacteria assume this form called bacteroids, which are contained within vesicles formed by the root cell
Card Set
Soil and Plant Nutrition
life 103