Effects of H2S on Crop and Forest Plants

Abstract

Continuous fumigation of alfalfa, grapes, lettuce, sugar beets, California buckeyes, ponderosa pine, and Douglas fir with 3000 parts per billion (ppb) H2S caused leaf lesions, defoliation, reduced growth, and death of sensitive species. Three hundred ppb caused lesser but similar effects. Sulfur accumulated in leaves depending upon dosage. Lower levels of H2S, 30 ppb and sometimes 100 ppb, caused significant stimulation in growth of lettuce, sugar beets, and alfalfa. The stimulation occurred at certain times of the year. Addition of 50 parts per million (ppm) of CO2 to fumigation atmospheres overcame growth reduction cause by 300 ppb H2S in lettuce and sugar beets. Two varieties of grapes and one variety of each of pears and walnuts were fumigated with the highest ambient levels of H2S found near the Geysers, treble ambient H2S and amounts of SO2 equivalent to treble levels of H2S. No deleterious growth or fruiting symptoms were observed which could be ascribed to the treatment.