What are fair daily wages for farm workers and how do I decide what to pay?

There is no single national figure, daily farm wages vary a lot by state, by season and by the task. As a rough guide unskilled farm labour in many states falls in a band of roughly 300 to 500 rupees a day, with skilled or peak season work going higher, but Punjab, Haryana and Kerala usually run well above this while parts of central and eastern India run lower. The honest answer is to check three local references: the prevailing rate other farmers in your village are paying this season, the state notified minimum agricultural wage (your labour or panchayat office can tell you), and the MGNREGA daily wage rate for your state which acts as a floor that workers compare against. Pay at or a little above the local going rate if you want reliable people. Also remember the full cost often includes tea, a meal or transport, so factor that in. Confirm the current local rate before you fix anything because it moves every season.