Bromine in wheat grown on soil fumigated with methyl bromide

Patches of discoloured ("scorched") plants developed on winter wheat growing in a field that had been fumigated with methyl bromide. Scorching was most marked round the methyl bromide injection sites and was associated with bromine uptake by the plants: the above‐ground parts of the scorched plants contained up to 0.61% bromine. In one scorched area, the first, second and third wheat crops after fumigation contained 0.42, 0.25 and 0.09% bromine respectively, so that three years was not sufficient to leach all the residual bromine from the soil. The greater the organic content of a soil, the more bromine remained after fumigation with methyl bromide. Thus a soil containing 2.81% organic carbon contained 63 ppm bromine after fumigation in the laboratory, whereas an otherwise similar soil with 0.93 organic carbon contained only 25 ppm. The residual bromine from methyl bromide fumigation could be extracted with N potassium sulphate, whereas the native soil bromine could not.