Rotating Butternut Squash

I don't know any soil borne diseases which would develop from repeat sowing of squashes on the same spot, provided you top up nutrients by adding manure, etc (squashes are greedy feeders), I would have thought it OK.  There are some insects which overwinter in the soil that could pose a problem, but as you are planning on removing the mulch, I recommend you turn the soil to ensure the birds, etc get to the soil and strip out any pupae that may be living in the soil.

I am sure someone else will comment if they know of something different.

I have been through a selection of books and online while checking out "crop rotation" and and the majority said that squashes do not need to be rotated and can be grown in the same bed every year as they do not harbour soil deseases like club root etc.

Therefore I plan to keep one bed as a permanant squash bed, but as mentioned before, squashes are hungry plants and a good feed/mulch is recommended.