salt

salt will build up in your soil if you use well or river water,
here you can see a water stain from the water here

it is that curved dark line on the dirt,
most of the time you will never see it at all,
but it will take farm fields that did well for a long time,
and it will make them grow nothing but barley (it can take salt fairly well)

past civilizations often love wheat (because it tastes good)
then change over to barley when the salt builds up (because that is all they can grow)
usually takes 100 to 200 years

good drainage will help,
clean water will help,
using rain water only will solve the issue entirely (this is called dry farming),
now this is a long term issue and will not get your home garden plot for a long time,
but from reports I here, most of the farm land in the USA will hit this limit in 5 to 10 years,
not sure if they are correct reports, but it is not like that sort of thing has not happened to others before.

so using as little well water as you can will help,
most modern farmers just use more water and fertilizer to fix other issues,
and that leads to bad places,
don't follow (at least not for long)

just think of the kitties, what will they eat ?