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