How can fertilizers that are used on land lead to water pollution?

Question

How can fertilizers that are used on land lead to water pollution?

Answer 1

it is worst pollution by pestcides, (poisons)

Fertilizers are food for plants, sometimes contain sulphur, ammonia, that is why, but pesticides are worst.

Answer 2

when it rains, the water runoff to nearby lakes and rivers

or water is absorbed into the ground, and these underground waterbeds ultimately leads into oceans etc.