Grass scorch due to pot ale

SUMMARY Grass scorch sometimes occurs when pot ale, a waste product of malt whisky distilling, is used as a liquid fertiliser. Experiments performed on grass turves show that a high concentration of solids in the pot ale, and a large amount of foliage on the sward result in higher amounts of scorch, as determined by visual assessment. Sward yield is independent of the amount of leaf scorch but appears to be linked to the proportion of dead tillers or plants in the sward. It is suggested that leaf scorch itself does not limit yield, but if the scorching compound runs off foliage and acts against roots then tiller or plant death may occur, accompanied by a yield loss. This interpretation may help to explain some conflicting evidence on scorch effects in the literature.