Fertilisers

• • There are 3 macronutrients that plants need - nitrogen (in the form of nitrates), phosphorus (in the form of phosphate ions) and potassium (in the form of potassium ions) - all are needed in relatively high concentrations 
• • Reasons: nitrogen needed for dna, proteins etc
  • Phosphorus needed for atp, nadp etc
  • Potassium needed for stomata opening and closing 
• • Inorganic fertilisers - manufactured artificially and contain minerals and synthetic chemicals  - can be in the form of powders, pellets - or diluted in water and applied
• Advantage of inorganic fertilisers- Known concentrations of nutrients - can be tailored to suit crop species 
• Disadvantage of inorganic fertilisers- Risk of leaching - easily washed out of soil -  very soluble
• • Organic fertilisers- derived from animal matter or vegetable matter. Naturally occurring organic fertilisers
• Advantage of organic fertilisers - Less likely to leach
• Disadvantage of organic fertilisers - Unknown quantities of each nutrient
• Eutrophication:

  • If too much fertiliser is added to soil, there is risk of it washing out into rivers/streams etc
  • When nutrients move from agriculture into freshwater environments - this is called leaching
• What is the process called when nitrates and phosphates are washed from the soil?

  Leaching
• When does leaching usually occur?

  When particularly large amounts of rainfall have occurred
• Where do nitrates enter after being washed from the soil?

  Lakes, streams, ponds, and rivers
• What effect do nitrates have on algae growth?

  They promote the growth of algae at the surface, causing algal blooms
• What is the consequence of algal blooms on light penetration in water?

  They block light from penetrating below the surface
• What happens to aquatic plants lower in the water due to algal blooms?

  They cannot photosynthesize and die