Extensive scientific literature, including global meta-analyses and isotope-tracing studies, confirms that plants exhibit distinct nutritional preferences for specific forms of nitrogen such as ammonium, nitrate, and organic nitrogen depending on species, climate, and environmental conditions.
The retrieved papers consistently demonstrate that plants have distinct uptake preferences for various chemical forms of nitrogen (ammonium, nitrate, organic nitrogen like glycine), influenced by factors such as climate, soil conditions, plant functional types, and root transporter gene repertoires. Multiple studies using 15N labeling directly document these preferences. There are no papers refuting the core claim that plants exhibit nitrogen form preferences.