• Nitrogen in the environment : nitrogen's most common forms 

    Killpack, Scott C.; Buchholz, Daryl (University of Missouri. Extension Division, 1993)
    "Nitrogen is important for all plants to live, and it comes in many forms. Although the atmosphere is mostly made up of nitrogen, it is in the form of a gas known as dinitrogen N2. Plants cannot use this form. Dinitrogen, ...