pay the field workers overtime after 40 hours and not 60

I've worked in the field work (agriculture) for about 2 years and the way they treat people and silence them are horrible Most people are scared to defend their rights do to the lack of information and most are immigrants. We go threw a lot from the heat , cold , no vacation , no pregnancy leave , no days off and I feel it should be right that we got paid overtime after 40 hours and not 60.