Table 2.
13C, C, and N in dissolved organic matter and microbial biomass. Cmic, Nmic, DOC, and TDN are means in μg g−1 dry weight, and 13Cmic and 13C in DOC are atom% excess.
| Pool | Cmic | Nmic | DOC | TDN | 13Cmic | 13C in DOC | (C/N)mic | |
|---|---|---|---|---|---|---|---|---|
| Rhizosphere soil | no N | 610.28 (15.95) |
142.12 (4.69) |
154.68 (6.27) |
27.62 (3.16) |
0.47* (0.05) |
0.17* (0.06) |
4.31 (0.10) |
| +N | 665.6 (24.63) |
141.96 (5.94) |
139.26 (3.79) |
29.98 (7.4) |
0.61* (0.06) |
0.15* (0.06) |
4.70 (0.12) |
|
| Bulk soil | no N | 655.13 (30.75) |
126.36 (6.05) |
145.35 (25.47) |
25.97 (3.3) |
0.20* (0.02) |
0.03* (0.01) |
5.26 (0.34) |
| +N | 620.07 (18.81) |
132.21 (7.75) |
179.85 (11.92) |
36.2 (7.86) |
0.18* (0.04) |
0.03* (0.01) |
4.77 (0.24) |
|
| Litter | no N | 1725.91 (137.64) |
286.29 (33.68) |
2867.67 (112.47) |
811.58 (45.18) |
0.10* (0.05) |
0.01* (0.00) |
6.22 (0.44) |
| +N | 1822.26 (206.47) |
259.31 (39.96) |
3004.41 (95.22) |
857.49 (110.57) |
0.09* (0.03) |
0.01* (0.00) |
7.53 (0.68) |
Cmic, C in microbial biomass; 13Cmic, 13C in microbial biomass; Nmic, N in microbial biomass; DOC, dissolved organic C; TDN, total dissolved N; (C/N)mic, C/N ratio in microbial biomass. Standard error is shown in brackets. Asterisks indicate significant difference to control (p < 0.05) in atom% 13C (comparison via Mann-Whitney U-test for equal medians; n = 7). No significant differences were detected between +N/noN compartments (comparison via Mann-Whitney U-test for equal medians; n = 7).