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Elevated CO2, but not defoliation, enhances N cycling and increases short-term soil N immobilization regardless of N addition in a semiarid grassland
| Content Provider | Semantic Scholar |
|---|---|
| Author | Dijkstra, Feike A. Hutchinson, Gordon L. Reeder, Jean Dolan Lecain, Daniel R. Morgan, Jack A. |
| Copyright Year | 2011 |
| Abstract | Abstract Elevated CO 2 and defoliation effects on nitrogen (N) cycling in rangeland soils remain poorly understood. Here we tested whether effects of elevated CO 2 (720 μl L −1 ) and defoliation (clipping to 2.5 cm height) on N cycling depended on soil N availability (addition of 1 vs. 11 g N m −2 ) in intact mesocosms extracted from a semiarid grassland. Mesocosms were kept inside growth chambers for one growing season, and the experiment was repeated the next year. We added 15 N (1 g m −2 ) to all mesocosms at the start of the growing season. We measured total N and 15 N in plant, soil inorganic, microbial and soil organic pools at different times of the growing season. We combined the plant, soil inorganic, and microbial N pools into one pool (PIM-N pool) to separate biotic + inorganic from abiotic N residing in soil organic matter (SOM). With the 15 N measurements we were then able to calculate transfer rates of N from the active PIM-N pool into SOM (soil N immobilization) and vice versa (soil N mobilization) throughout the growing season. We observed significant interactive effects of elevated CO 2 with N addition and defoliation with N addition on soil N mobilization and immobilization. However, no interactive effects were observed for net transfer rates. Net N transfer from the PIM-N pool into SOM increased under elevated CO 2 , but was unaffected by defoliation. Elevated CO 2 and defoliation effects on the net transfer of N into SOM may not depend on soil N availability in semiarid grasslands, but may depend on the balance of root litter production affecting soil N immobilization and root exudation affecting soil N mobilization. We observed no interactive effects of elevated CO 2 with defoliation. We conclude that elevated CO 2 , but not defoliation, may limit plant productivity in the long-term through increased soil N immobilization. |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/j.soilbio.2011.07.017 |
| Alternate Webpage(s) | https://www.ars.usda.gov/ARSUserFiles/54092500/Morgan/248.%20Dijkstra%20SBB%202011.pdf |
| Alternate Webpage(s) | https://doi.org/10.1016/j.soilbio.2011.07.017 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
