Methyl Bromide Soil Fumigation Alters Plant Element Concentrations

Abstract

AbstractSoil fumigation is used to eliminate plant pathogens and weeds in commercial practice and to eliminate organisms in controlled experiments, e.g., vesicular arbuscular mycorrhizal fungi (VAMF). This study was conducted to study the effect of methyl bromide fumigation on plant accumulation of 14 elements and assess plant colonization by VAMF after fumigation. Field experiments were conducted near Mead, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll). Corn (Zea mays L.) sorghum [Sorghum bicolor (L.) Moench], and soybean [Glycine max (L.) Merr.] were used in the experiments. Fumigation increased Al, Br, Ca, Fe, Mg, Mn, and Si and decreased Cu, K, P, and Zn shoot concentrations in all three plants. Three weeks after germination, shoot Al was sevenfold greater in sorghum and soybean and 16‐fold greater in corn from fumigated plots than in shoots from nonfumigated plots. Shoot bromide concentrations from fumigated plots were sixfold greater in sorghum and 17‐ to 18‐fold greater in corn and soybean than shoots from nonfumigated plots. Lower P and Zn shoot concentrations from fumigated plots were attributed to fumigation‐induced suppression of VAMF root colonization or an ion balance problem resulting from the enhanced uptake of Al, Br, and other ions after soil fumigation. At harvest, Al was still three‐ to 10‐fold and Br eight‐ to 20‐fold greater in fumigated plot stover compared with nonfumigated plots. This study shows that methyl bromide fumigation alteration of plant uptake of Al, Br, Ca, Fe, Mg, Mn, and Si should be considered when interpreting experiments using methyl bromide soil fumigation.