Galvanized Water Trough Raised Bed Design Help
I am looking to build five raised beds by using the galvanized water troughs as the containers. I live in the Pacific Northwest (Western Washington) and have had luck with the wooden raised beds in the past.
I'm stuck in between two designs and would love advice from people who know what they are doing to help figure this out.
The first design is a wicking one, seen here: http://www.maryjanesfarm.org/Recipes-Patterns-Instructions/horse-troug h-gardening.pdf
The design looks great but the problem is it's obscenely expensive to get the poly mesh she references here. I can't find it for any less than $250 for the 5 beds, plus $100 for shipping. That, on top of the price of the troughs makes it a spendy endeavor. I am intrigued however by the self-watering system, only having to fill it through the feeder tube and not having to drill/seal the holes (so the galvanized metal won't rust).
Option two would be a more standard design with a drip irrigation system. Also pricey but I have a lot of the supplies and it's fairly simple. The problem I'm having, however, is with what goes in the bottom. I've read on here to not do a coarse gravel as it doesn't help with drainage. Do you recommend just the soil throughout? With our wet weather I want to make sure the soil doesn't get too compacted. I do have one of these that is two years old with raspberries which is doing fine (and is all soil), but my personal opinion is that raspberries have no problem growing in anything.
Regardless I will put them on a leveled base of pavers so they don't sit directly on the soil. I will also likely put gravel in the middle of the structure (if it will help with drainage). I will also be coating the inside with a water-based rubberized paint to protect from the zinc leaching which is a slight risk, but still better to do it right the first time.
Any recommendations are appreciated as is experiences with this.