PEX protection?

I just got through digging a trench four feet deep and eighty feet long for a water line. I am using 3/4 inch PEX tubing. Does the tubing need an outer protection like conduit. It has to go around one corner and I did dig that corner on a large radius so as not to kink the tubing. Some guys up the road from me were using electrical conduit as a protective barrier over copper. The conduit is ridged and I was thinking about using black corrugated drain pipe since it is flexible. The drain pipe is four inches in diameter. Or does the PEX need that protective barrier?

Code doesn't require protection around PEX in the ground.

3/4" pipe?
Has that been sized properly?

My wife and I live in a small house with a well that produces from 26 to 45 lb. of pressure. Just recently the water authority laid water lines and we tapped into the line with a pit that contains the regulator, meter, and back flow valve. The specs call for type k soft copper tube 3/4" to the pit and recommend a 5 ft. length coming off the house side of the pit before hooking on the pex. The well gave us plenty of water at good volume with the pressure stated above. The authority water comes in at a steady 50 lb. psi so this will be a huge improvement with plenty of volume and no odor. Thanks for your answer.

Pex

Well, since 3/4" PEX is just about the size of 1/2" copper, which is also about half the size of 3/4" copper, you could be undersized.