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Table 1 Soil characteristics and root decomposition rate constant (single exponential) under different forms of N fertilization and control treatments

From: Effects of different forms of nitrogen addition on microbial extracellular enzyme activity in temperate grassland soil

  N0 (Control) N1 (10:0) N2 (7:3) N3 (5:5) N4 (3:7) N5 (0:10)
Total C (mg C g−1 soil) 28.1 (2.02)a 27.6 (2.84)a 27.4 (2.39)a 28.6 (1.62)a 29.7 (3.01)a 31.3 (2.39)a
Total N (mg N g−1 soil) 2.03 (0.05)b 2.90 (0.06)a 2.73 (0.03)ab 2.91 (0.07)a 2.90 (0.03)a 3.30 (0.07)a
Soil C:N 13.5 (0.27)a 10.7 (0.30)ab 10.3 (0.19)b 9.71 (0.24)b 9.85 (0.38)b 8.93 (0.63)b
DOC (μg C g−1 soil) 42.3 (5.01)d 50.9 (6.13)c 64.1 (4.07)c 67.9 (4.94)c 85.5 (6.72)b 240.2 (19.0)a
DON (μg N g−1 soil) 10.69 (2.16)b 19.85 (3.56)a 21.9 (2.75)a 22.1(2.70)a 19.6 (3.52)a 23.9 (2.63)a
Available P (μg P g−1 soil) 6.26 (0.09)a 7.58 (0.04)a 7.27 (0.13)a 6.83 (0.09)a 6.77 (0.09)a 6.59 (0.10)a
MBC (μg C g−1 soil) 45.8 (5.47)e 55.8 (2.06)d 122.1 (6.09)c 151.2 (5.49)c 193.8 (8.21)b 468.1(10.7)a
MBN (μg N g−1 soil) 8.91 (1.02)b 9.30 (0.31)b 10.6 (1.89)b 16.6 (0.75)b 21.5 (4.05)b 31.9 (1.04)a
Microbial biomass C:N 7.41 (1.32)c 7.16(1.63)c 10.28 (2.11)b 9.72 (2.53)b 9.90 (1.09)b 13.3 (3.68)a
pH 6.27 (0.05)a 5.72 (0.12)c 5.84 (0.11)b 5.90 (0.16)b 6.01(0.07)b 6.08 (0.18)ab
Root decomposition rate constant (k, year−1) 0.53 (0.003)c 0.56 (0.009)b 0.61 (0.006)a 0.64 (0.001)a 0.63 (0.007)a 0.56 (0.01)b
  1. Values are means ± SE (n = 6)
  2. Control: N0; IN: N1 (IN:ON = 10:0); Mixed N: N2, N3, N4; ON: N5 (IN:ON = 0:10)
  3. Different lowercase letters within a row indicate significant differences for Tukey’s HSD post hoc multiple comparisons among different forms of N treatment (P < 0.05)
  4. Root decomposition data from Dong et al. (2020)
  5. DOC dissolved organic carbon, DON dissolved organic nitrogen, MBC microbial biomass carbon, MBN microbial biomass nitrogen