Thanks for sharing this method. It seems almost inconceivable to me that potatoes can be grown without trenching/hilling them! Once or twice I planted potatoes and then failed to get them trenched when the time came, and yields were really poor. But perhaps that is because the trenching we do is a way of suppressing the weeds too. (We turn the weeds over with the spade so they also serve as a green manure, and usually put fish around the plants under the trenching.)
This method might work well at my friend's farm, where the soil is really rich (and of course applying some ferts at planting time as you do).
Is there anything you can tell me about the right plastic mulch? Is it durable enough to use for several seasons, or is one type better/more durable than another? I would like to look into the cost for that. Thanks!