What is the relation between human activities and the nitrogen cycle?

The relation between human activities and the nitrogen cycle can be summarized in simple points:

1. Human activities, such as the use of fertilizers, increase the amount of nitrogen cycling between the living world and the soil, water, and atmosphere.
2. Fertilizer application enhances microbial nitrification and denitrification processes, leading to the release of nitric oxide (NO) and nitrous oxide (N₂O) into the atmosphere.
3. Nitrous oxide (N₂O) is a potent greenhouse gas, about 300 times more effective than CO2, contributing to global warming and climate change.
4. Human-induced nitrogen enrichment in the soil leads to soil acidification, which can affect mycorrhizal communities and alter plant species composition.
5. In aquatic ecosystems, excessive nitrogen loading can cause downstream freshwater systems’ acidification, leading to aluminium toxicity and the decline of pH-sensitive fish species.