Plants Utilize Nitrogen, Phosphorus, and Potassium

Element Form Available to Plants Relative Number of Ions in Dry Plant Material  

Source Frank Salisbury and Cleon Ross, Plant Physiology. Belmont, CA Wadsworth, 1985. 

Two pathways for nitrogen fixation, a source of nitrogen for plants, (a) Both free-living bacteria in the soil and microorganisms in root nodules produce ammonium ions, (b) Lightning provides the energy needed to form nitrate ions from atmospheric nitrogen. 

In a natural setting, nitrogen fixation is the original source of ammonium and nitrate ions in the soil. Most of this fixed nitrogen, however, is recycled from one 

Murray Nabors, Introduction to Botany. San Francisco Benjamin-Cummings, 2004. www.aw-bc.com 

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