Growing food adjacent to yew hedge?

I have a dense, low, yew hedge that I want to keep.  We pruned it back significantly, revealing a long rectangle of bare soil that had been shadowed by dense branches.  I decided that, for a couple reasons, that would be a neat location to try growing potatoes above ground, using deep/ iterative mulching/ burying to see how much production I could get.  We started with about 6 inches of compost, and buried the seed potatoes and they are all doing great.  Now, I am having second thoughts.  Although they weren't buried into the soil that has been under yew branches for years, is there any concern about toxicity transferring into the potatoes?

My design also currently calls for 2 trellised hardy kiwis just outside of this zone, with the plants being buried less than 5 feet from the current yew branches, and even closer to the bare-ground rectangle space.  Unlike the potatoes, these plants would remain in their locations indefinitely.

I found this article, but have not been able to unearth any additional insights into potential risks of packing food plants so close to yews:  http://extension.psu.edu/natural-resources/forests/woodpro/technotes/toxicity-of-yew-wood-and-roots

Any experiences or additional information out there?  I have found many mentions of yew shrubs and trees throughout these forums, in which they seem to be considered just another plant to integrate into a permie landscape.    This gives me hope that my design might be acceptable.

Many thanks~

Ann

Yew is quite poisonous thus here in Europe was often grown in Church Yards away from farm animals. As far as I am aware that only applies if you eat the leaves or the berrys and does not effect other plants unlike for instance the effects of  walnut trees
. As long as there is enough sun and water and the soil is good enough you should be ok I think  

David Livingston wrote: As far as I am aware that only applies if you eat the leaves or the berrys

All parts of the plant are highly poisonous except the red part of the fruit.  I have eaten them on occasion but it is a slightly alarming experience and I make sure to not do it if any children could see and imitate.  Also they exude a very slimy juice which makes it quite difficult to extract and discard the seed.

But no, I have never heard either of yew poisoning the ground.  Nothing much tends to grow directly under yew trees but I think that is because they cast a pretty dense shade.  I've heard of plants that stop other plants from growing, but I've never heard of a plant that could allow other plants to grow nearby yet somehow transfer its toxins into those plants so they would be poisonous to a creature that ate them.  

Don't be concerned about toxins leeching. On the other hand yew makes dense shade and the root system tends to dry the surrounding soil. I'm not sure how well things would grow right up against them. We have yew and the garden beds that are shaded by them struggle. Those in full sun do better, especially when mulched with compost.

Thank you to everyone~ you have eased my mind about this topic.

Michael, these are low shrubs, a dense hedge that we trim below the height of our living room windows.  I want to keep them because they offer nice shelter to wildlife, both voles/ shrews and birds.  They aren't casting shade onto the potato bed nor the locations where I want to plant the hardy kiwi.  They might potentially compete for water, so I am using deep compost and mulching in both places. All of the mentioned plants are in full sun. The whole spot is adjacent to a rain barrel, too, making them easy to water as needed.  I will keep that in mind.  All of my garden beds drain quickly with fluffy light organic soils on a gentle slope, and dry out after even a few warm/ windy/ dry days... I am working on that with deep mulching, a small hugelkulture bed, lasagna beds and, this fall, I hope to dig swales.  It is quite an issue in general around here.

Sounds fine then. Mine are 10ft high