Wheat and soil bromide dynamics after fumigation with methyl bromide in a mediterranean climate

Soil and wheat bromide dynamics are studied in methyl bromide-fumigated plots in a Mediterranean climate. Bromide residues range between 5 to 10 ppm in the fumigated soil and they are distributed to a depth of 50-60 cm, where a compacted layer exists, in accordance with soil organic matter and moisture distribution. The total amount of bromide in soil is 5.8 gm^-2 up to a depth of 1 m and it remains almost constant during the wheat growth period. The plant bromide concentration decreases throughout the development of spring wheat. The bromide distribution in the different plant organs was identical in the two years studied and it is correlated with the chloride content. Fumigation increases the phosphorus concentration in wheat and does not affect sulphur and chloride. Though the bromide concentration in the fumigated soils is high, the levels in the plants growing in it do not cause scorched areas. This may be due to antagonic Br/Cl and Br/NO₃ effects.