Organic forms of nitrogen on any site are usually locked into complex and tightly held compounds. Most of these organic forms of nitrogen are unavailable for tree use. Tree-available and uptakable forms of inorganic nitrogen are primarily ammonium (NH4+) and nitrate (NO3-). Note it is possible for organic nitrogen forms like urea and free amino acids to be taken up by trees to a limited degree. Between unusable organic nitrogen forms and tree-preferred inorganic nitrogen forms, lie many soil organisms (almost exclusively bacteria). These bacteria use whatever nitrogen source is accessible to live and, in the process, transform nitrogen into another form.
WSFNR-20-73C_Coder.pdf (215.02 KB)
Community and Urban Forestry