My father (much better gardener than me) always told a tale that during WW2 he was stationed up in Oban doing embarcation of air crew .
He got a load of seaweed dug it in to the garden of the B&B he was staying in. He said he got the best crops he had ever had, especially brassicas. To the point that when the ministry of food were going round on checks another neighbouring B&B owner complained that it was alright for his landlady to manage on the rations because she had got a professional gardener in who was suplying her with all this fantastic produce!
Iain R