• Leaf lettuce grows bigger when dosed with low amounts of hydrogen sulfide.Jupiterimages/Photos.com/Getty Images
  
  Hydrogen sulfide is a noxious chemical that is toxic to humans. The chemical finds it uses in the plant world, where scientists have researched its potential as a fertilizer and weed killer. Results indicate that hydrogen sulfide has positive and negative effects on plant growth depending on the dosage administered to the crop.
  
  

Stunted Growth

• According to a 1978 study published by the University of California and the Statewide Air Pollution Center, high doses of hydrogen sulfide at 100 to 500 parts per million significantly stunted growth in 10 common weed species. Younger plants showed inhibited growth much sooner than more established plants. Those plants in drier soil were also more susceptible to damage. The study also determined that these high levels of hydrogen sulfide are not likely to occur in the environment normally and that emissions from industrial centers containing hydrogen sulfide are not likely to cause this type of plant damage.
  
  

Leaf Damage

• High doses of hydrogen sulfide also causes leaf damage in a variety of plants. For example, alfalfa leaves may show white lesions on leaves within five days of high dose exposure to hydrogen sulfide. This damage may be particularly severe in environments with high humidity. This is due to increased plant respiration, which allows more of the chemical to be absorbed. The damage causes the plant to expend more energy attempting to repair itself, which can lead to stunted growth and low crop yield.
  
  

Fertilizer

• Low doses of hydrogen sulfide may be used as a replacement for sulfur in fertilizer, according to the University of California. Sulfur helps maintain proper photosynthesis and is a key ingredient in chlorophyll, the chemical that keeps green plants green. According to the California Agriculture website, low doses of hydrogen sulfide actually increase crop yield and plant size. Yield of lettuce and sugar beets was increased when fumigated with 30 parts per billion of the chemical.