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
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• ==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
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