Soils
Is the N in manure different than the N in commercial fertilizers?
Plants utilize nitrogen (N) indiscriminately whether it originates from an inorganic fertilizer or an organic source. Plants utilize either the nitrate or ammonium form; however preference exists depending on the plant age and type and the environment, among other factors (Tisdale et al., 1993). Each N fertilizer, whether organic or inorganic, has characteristics that should be considered for most efficient utilization.
Observed differences due to N nutrient source are most often due to non-plant nutrition factors. Nitrogen in organic fertilizers is part of complex organic molecules that must be mineralized to nitrate or ammonium (a biologically mediated process) before plant uptake. For this reason, N content of organic fertilizers such as animal manures usable by plants in the year of application is 50 to 60 percent of the total N content.
Differences in observed current year availability of inorganic N fertilizers are most often attributable to the management of the fertilizer material and environmental factors such rain, temperature, and surface residue.
