Introduction:
Fertilisers are commonly used in agriculture to enhance crop growth and increase yields. However, improper use and management of fertilisers can lead to water pollution.

Leaching:
- When fertilisers are applied to the soil, they can be easily washed away by rainwater. This process is known as leaching.
- The excess fertilisers, containing nutrients like nitrogen and phosphorus, can seep into groundwater or surface water bodies, leading to water pollution.

Surface Runoff:
- Fertilisers applied to fields can also be carried away by surface runoff during heavy rainfall.
- The runoff containing fertilisers can flow into nearby rivers, lakes, and streams, causing nutrient pollution in the water.

Eutrophication:
- Excessive nutrients from fertilisers in water bodies can lead to eutrophication.
- Eutrophication is a process where the increased nutrient levels promote the growth of algae and other aquatic plants, leading to oxygen depletion and harming aquatic life.

Toxic Algal Blooms:
- The algae growth resulting from nutrient pollution can lead to toxic algal blooms.
- These blooms can produce harmful toxins that can be harmful to aquatic organisms, animals, and humans if ingested or come in contact with contaminated water.

Solutions:
- Properly manage and apply fertilisers to reduce runoff and leaching.
- Use precision agriculture techniques to apply fertilisers only where needed.
- Implement buffer zones and vegetative strips to capture and filter out excess nutrients before they reach water bodies.
In conclusion, fertilisers have become a source of water pollution due to their improper use and management in agriculture. It is essential to adopt sustainable practices to minimize the impact of fertilisers on water quality and protect the environment.