Here in Algonquin Park (Northern Ontario, Canada) we run electrical, propane, phone and data cables everywhere underground, we use 75# black poly water pipe, it's cheap and plentiful, comes in sizes up to 4", you can make it any length with connectors and it is flexible; you can curve around rocks and roots, etc.
When burying anything, always put a 2x4 or 2x6 directly over the pipe or conduit before you bury it, cut it into 2 to 8 foot lengths depending on how straight or up and down your pipe is, then if you ever need to dig any other holes in the area you have have some form of protection, something that your shovel will hit before you carve through the pipe or conduit. Don't wimp out on the depth either, bury a minimum of 2', better yet 3 to 4' if the terrain allows, with 120/240 electrical follow your local code re depth.
Another thing is lightning, any ground strike (in the countryside) with-in 1 to 2 kilometers can induce sufficient energy into the cabling (including electrical) to damage or destroy your electronics, as said by others, protect your equipment. We've lost PLC controlled sewage and pump controllers with strikes as close as 1/2 km, and this is industrial equipment, well protected, the surge just wipes out the protection and equipment when that close.