Fertilisers

1. Need

1.1. In agriculture, material is not re-cycled

1.2. Nitrate needs to be added

2. Natural

2.1. Organic

2.2. Manure

2.3. Bone meal

2.3.1. crushed bone

2.4. Dried blood

2.5. Hoof and horn

2.6. Urea

2.7. Need more decomposition

2.8. Slower to act

2.9. Persistent in soil

3. Artificial

3.1. Inorganic

3.2. Ammonium nitrate

3.3. Ammonium sulphate

3.4. Produce biggest rise in productivity

3.5. Immediately available

3.6. Soluble, leaches out of soil

4. Eutrophication