The diagram shows a simplified version of the nitrogen cycle.
Name the processes PPP, R R\,R and S S\,S shown on the diagram.
Process R R\,R happens most rapidly in well-aerated soils (aerobic conditions). (i) What is meant by aerobic conditions?
Name the group of organisms that carry out process RRR.
Farmers can use crop rotation of clover or peas (legumes) to maintain soil fertility. (i) Explain how growing legumes increases the nitrate concentration in the soil.
Give one ecological problem caused by the excessive use of artificial chemical fertilisers on nearby aquatic ecosystems.
