how does farming contribute to non-point pollution?

Answer 1

There are several ways that farming can cause pollution. the most common is using excess fertilizer or fertilizing just prior to rain, if the farmer is not cautious with the amount of it he uses then when he irrigates or when it rains the excess runs into nearby rivers and creeks. How does this harm the environment? first it causes an explosion of growth in algae. As these plants then die, the rotting algae depletes the oxygen dissolved in the water and all life that needs oxygen dies.
Another way is using pesticides. especially if used in excess. These chemicals can and do cause illness in animals and humans. We have a choice we can eat the para cites in foods or the poisons that kill them,
Organic grown food is not supposed to use chemical fertilizers or pesticides. However without using them it would be nearly impossible to raise enough food for all American consumption, let alone feeding other parts of the world.

Answer 2

Runoff from the fertilizers and pesticides sprayed over the crops. Also, winds blow the fertilizers and pesticides off course and towards other places.