fertilisers

• Macronutrients are those that are needed in large amounts - NPK 
• Micronutrients are those needed in small amounts - iron and copper 
• Nutrients are absorbed through root hairs and are absorbed as ions dissolved in water. 
• Growing legumes helps to maintain nutrient levels in soil due to their nitrogen fixing modules. 
• Maintaining fields to prevent water logging can stop denitrification. 
• Crops can be rotated so crops don’t deplete certain nutrients. 
• Natural fertilisers are natural substances that decompose and release nutrients. 
• Natural fertilisers:

  • Slow release of nutrients 
  • Cheap 
  • Improves humus 
  • Food for soil biota 
• Natural fertilisers:

  • Small volume of nutrients 
  • Bulky 
  • Cannot be applied to growing crops 
  • Nutrient content cant be controlled
  • Risk of human pathogens 
• Artificial fertilisers are manufactured chemicals to provide specific nutrients. 
• Artificial fertilisers:

  • Controlled nutrient content 
  • Available for crop as soon as applied 
  • Easy application 
• Artificial fertilisers:

  • No humus 
  • No food for soil biota 
  • Expensive 
  • Energy intense manufacturing 
  • Leaching and pollution 
• Nitrates and phosphate are inorganic nutrient pollution sources. Nitrates are very soluble and phosphate are as not soluble but collect in water ways. 
• Nitrites can cause cancer and blue baby syndrome. 
• Eutrophication can cause the growth of toxic blue-green algae. 
• Nitrate pollution:

  • Use slow release fertilisers 
  • Reduce fertiliser use
  • Buffer strips 
  • Reduced ploughing 
• Phosphate pollution:

  • Adding iron sulphate to precipitate phosphate out of solution. 
• Organic nutrient pollution:

  • Eutrophication after the breakdown of manure when minerals ions are released.