‘Something ate my potatoes underground. What could have done this?

I went to harvest my potatoes from my raised bed a few weeks ago only to see that around 60 per cent were eaten underground. Any idea what would have eaten them? S Kemmy, Co Wexford
I am really sorry to be the bearer of bad news, but I think it’s very likely that rats are responsible for the damage caused to your potato crop. Unfortunately, the fact that the plants were growing in a raised bed only adds to the likelihood, providing exactly the kind of soil conditions (friable, free-draining) in which rats can comfortably burrow, the same reason why they can be a pest of compost heaps.
Omnivorous, rats will happily eat a wide variety of vegetables, grains, seed and fruits, either from (as in your case) living plants or from stored crops such as squash, pumpkins, beetroot and seeds. They will also happily raid bird-feeding stations. Ingenious, adaptable, and highly intelligent, they’re not dissimilar from us humans in their ability to spot any opportunity to find food and shelter, which is why they are also so strongly associated with human activities. The sad truth is that food growing is one of the latter unless careful precautions are taken. Indeed, according to a report by the BBC, it’s estimated that rats can be found on about 40 per cent of agricultural premises in the UK, which gives a sense of how very widespread they are.
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It goes without saying that rats also present a health risk to humans, especially in terms of any food crops that they’ve fed on. Weil’s disease can be passed through their fresh urine to the soil and then into fresh cuts or grazes on a gardener’s hands, or even by accidental ingestion of contaminated material.
In the case of your potatoes, my advice would be to bin the remainder of the crop, wearing gloves to protect yourself from possible infection. Then try to assess your garden or allotment from the point of view of any possible areas that may be providing suitable nesting sites.
Rats love to nest in undisturbed, sheltered areas with easy, close access to food. If, for example, you have supplies of bird feed or pet food stored in a nearby shed, make sure that these are in sealed, lidded containers. Keep bird feeders and bird tables clean and make sure that any food that falls on the ground is regularly collected and binned. Keep compost heaps covered and functioning properly to ensure speedy decomposition by making sure they’re well insulated, always adding alternating layers of carbon and nitrogen rich material and turning them to aerate them. It may also be necessary to employ the services of a reliable pest control company who can offer expert advice tailored to your site. Last but not least, consider getting a cat, which will do a huge amount to keep any rodent problem under control without the need to resort to poison bait.