[Robster]

This year I grew Arran Pilot first earlies.  I had some in the ground and some in recycling boxes.  They were grown in similar positions in the garden.  The boxes were beside a raised bed.  I harvested at the same time.  The yields were enormously different.  For the same area I reckon I had about three times the yield.  What is more from the boxes the spuds were very similar sizes and smaller than in the ground.  Of course it was easier to make sure I got all the spuds out of the box.

Is this other peoples experience?  Is this the same with second earlies and salads as well.  I am probably just going to do boxes next year

[DD.]

What is more from the boxes the spuds were very similar sizes and smaller than in the ground. 

That bit doesn't actually make sense! (but we get the gist).

Was the compost/soil the same?

That aside it's much easier to keep the moisture content of a box, or indeed straight soil, higher than in a raised bed, and that could be the reason. A raised bed will drain very quickly.

[arugula]

We grew a few varieties (7 - long story) last year in containers, well large bags actually. The yields were all small, as in small numbers of spuds. This year going back to growing them in the ground albeit a late decision and therefore an area of ground which should have been prepped better, we're getting much bigger yields.

[Robster]

Sorry yes a bit garbled.  The boxes were much higher yielding.  As you say easier to keep watered and fed as well.  The boxes were filled with garden  compost straight from the bin.  I fed both with a potato feed.  I have some newpers in boxes for Christmas now.  So it will be interesting to see how much I get out from there