The rational for this is that Carrot Fly, the principle pest for carrots, hovers at no higher than two foot, and so will be unable to attack the carrots, as they are above this height. It should also be an effective deterrent to mice and slugs- I hope. It has the added advantage of being a good height to work without bending down. I sieved the soil to remove any roots and small stones- even small stones can deflect a carrot root. leading to misshapen veg.
I covered the container with plastic sheeting to act as a mini-poly tunnel to increase germination, to gain another head start.
As this is an experiment, I also planted a control (ie, a line of carrot seeds in the soil, not enjoying ant of the protection and advantages of the ECB. If the ECB proves a success I will make a much larger one next year. If not, well there's no harm done, as I made it entirely out of recycled and reclaimed materials.