The diagram shows a simplified version of the nitrogen cycle.
Name the processes XXX, Y Y\,Y and Z Z\,Z shown on the diagram.
Process Z Z\,Z happens most rapidly in waterlogged, compacted soils (anaerobic conditions). What is meant by anaerobic conditions?
Name the group of organisms that carry out process ZZZ.
Farmers can use crop rotation involving alfalfa or soybeans (legumes) to improve soil fertility without chemical additions. Explain how growing these legumes increases the nitrate concentration in the soil.
Give one ecological problem caused by the excessive leaching of artificial chemical fertilisers into nearby aquatic ecosystems.
