Soil and Plant Nutrition

Soil and Its Ecosystem

• Plants take up water and nutrients from the soil through the root system (from upper layers of soil)
  • Plants that live in soil that is nutrient-poor use carnivoriy to get mineral nutrients
  • (ex/Genlisea uses underground leaves to capture soil organisms)
• Physical properties of soil
  • Texture (tough, pores, air, etc.)
  • Composition (what is it made of?)
• ==Cation exchange==: cations are displaced from soil particles by other cations, particularly H+
  • Displaced cations enter soil solution, taken up by roots
  • Negative ions do not bind with soil particles & can be lost from soil
  • Affected by pH
  • Cations are more available in acidic soil (low pH)
  • Hydroxil (OH-)
    • More hydroxil= more acidic
    • Less hydroxil= less acidic
    • More OH-= less H+
    • More H+= less OH-
    • Soil pH<5→ toxic aluminum ions become more soluble
    • Stunts root growth & prevents calcium uptake
• 
• ==Fertilization==: addition of mineral nutrients to the soil
  • Combats reduction in yields experienced when the same crops are grown in the same locations over many seasons
  • Soil management
  • Replaces nitrogen, phosphorus, and potassium
• American Dust Bowl of 1930s caused by soil mismanagement
  • Formed a lot of dust in the Midwest
  • Loose soil & dust
  • Soil mismanagement→ 30% less food production
• ==Sustainable agriculture==: use farming methods that are conservation-minded, environmentally safe, & profitable
• ==Irrigation==: BAD; drain on water resources because water is brought to an area where it isn’t usually available
  • Result in depleting of aquifers→ land subsidence (sinking of land)
  • Lead to salinization
  • ==Salinization==: concentration of salts in soil as water evaporates
    • Reduces water potential of soil solution and diminishes water uptake
• Excess minerals are leached from the soil & causes algal blooms
  • Algal blooms block the sun for plants→ plants die→ increase in bacteria
• \