Pöttinger Torro self-loading silage trailers: The last time we in the UK and Eire took serious buying interest in self-loading silage trailers was back in the 1980s. Then along came the round baler – and that, as they say, was that; the round package took over. So, what’s behind today’s renewed interest in silage wagons? Modern loaders, like the Pöttinger Torro, are part of the reason, as James de Havilland finds out