Installing a yard hydrant from home water line, do I need a backflow preventer or vacuum breaker?

I’m installing a yard hydrant off my house water line (well water). The hydrant will sometimes be used for garden drip irrigation and so will be open for days or weeks at a time. The drip system itself has a plastic vacuum breaker that runs inline before the fertilizer injection tank.

Do I need an additional backflow prevention device just to be safe? If so, what kind? There seem to be multiple options, the cheapest being an extra AVB that installs on the hose, the most expensive being a pressure vacuum breaker – the type that is used for sprinkler systems. Do I need anything like this? If so, what and where? I was imaging something installed underground on the water line itself, but that doesn’t seem to be common.