Are there Unaccounted Plant Sources of Limiting Nutrients

3 Are there Unaccounted Plant Sources of Limiting Nutrients  

The assumption hitherto has been that plants only, or almost exclusively, take up N in inorganic form as NH4 or NO,. This assumption has been questioned recently, and there are strong 

FIGURE 2 Biomass and nitrogen accumulation (means SE) in Erio-plioruin vaginatum grown in NO3, NH4, and amino acids (AA) during 24 days. Treatment responses with the same superscript letter above the bars are not significantly different at p s 0.05. (Redrawn from Chapin et al, 1993, with kind permission from Nature). 

FIGURE 3 Mean 6 N ( SE) of the bulk soil organic matter and plant species without mycorrhiza (NON), with ectomycorrhiza 1 (ECM) or ericoid mycorrhizal (ERl) fungi at four different heath or forest tundra sites, n is number of species analyzed. (From Michelsen et ill, 1998, with kind permission from Springer-Verlag). 

---