Plant effects on soil N mineralization are mediated by the composition of multiple soil organic fractions


Despite the topic of soil nitrogen (N) mineralization being well-studied, very few studies have addressed the relative contribution of different plant and soil variables in influencing soil N mineralization rates, and thus the supply of inorganic N to plants. Here, we used data from a well-studied N-limited grassland to address the relative effects of six plant and soil variables on net and on gross rates of soil N mineralization. We also addressed whether plant effects on soil N mineralization were mediated by changes in C and N concentrations of multiple soil organic matter (SOM) fractions. Regression analyses show that key plant traits (i.e., plant C:N ratios and total root mass) were more important than total C and N concentrations of bulk soil in influencing N mineralization. This was mainly because plant traits influenced the C and N concentration (and C:N ratios) of different SOM fractions, which in turn were significantly associated with changes in net and gross N mineralization. In particular, C:N ratios of a labile soil fraction were negatively related to net soil N mineralization rates, whereas total soil C and N concentrations of more recalcitrant fractions were positively related to gross N mineralization. Our study suggests that changes in belowground N-cycling can be better predicted by simultaneously addressing how plant C:N ratios and root mass affect the composition and distribution of different SOM pools in N-limited grassland systems.

DOI: 10.1007/s11284-010-0777-0

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@article{Fornara2010PlantEO, title={Plant effects on soil N mineralization are mediated by the composition of multiple soil organic fractions}, author={Dario A Fornara and Richard D. Bardgett and Sibylle Steinbeiss and Donald R . Zak and Gerd Gleixner and David Tilman}, journal={Ecological Research}, year={2010}, volume={26}, pages={201-208} }