Dripper system for large outdoor grow

So I will have them in 4x4x2 holes this year. Going to be placing some alfalfa hay over the top to prevent drying out of the top part of the soil as I hear this is wehre the most microbes and mycorrhizae are. Just curious if anyone has some tips on proper watering limits on a dripper system for that amount of mass of soil. Its 1.2 cubic yards of soil roughly give or take. Any suggestions or thoughts would be greatly appreciated thanks

I'm experimenting with a drip system right now. Near as I can tell so far for more even water distribution, is to use multiple adjustable drippers. I bought this...https://www.amazon.com/Drip-Irrigation-Container-Gardening-Deluxe/dp/B007JADWDG

I'm running a timer and chlorine filter with it too. This kit is cheap than going to home depot and buying evening separate.