- leaching
- eutrophication
Leaching occurs due to the fact that inorganic fertilisers contain soluble ions like ammonium and nitrate. They don’t remain in the soil for very long and instead leach out into local water supplies like lakes and rivers.
This leads to eutrophication. Eutrophication is the process by which water that is normally clean and only contains a few nutrients and a little algae (oligotrophic) becomes a swampy mass of plants and detritus (hypertrophic) due to the high number of nutrients it contains. This not only disrupts the food chain but eventually destroys it. Larger plants die due to the fast growing algae, unable to compete for light, and a large amount of algae dies before it can be consumed leading to a mass of detritus. Decomposing microbes multiply quickly, using up the oxygen faster than it can be replaced and leading to the death of larger aerobic animals and the growth of toxic, anaerobic bacteria.