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Table 1 Soil and microbial biomass chemistry

From: C:N:P stoichiometry and nutrient limitation of the soil microbial biomass in a grazed grassland site under experimental P limitation or excess

  Fertiliser treatment
  0_0 0_30 15_5 15_15 30_0 30_30
pH 5.5 5.7 6.1 5.9 6.1 5.8
Soil C (g) 46.1 (2.50) 48.7 (0.9) 47.7 (2.2) 50.4 (4.2) 56.3 (3.1) 53.6 (4.5)
Soil N (g) 4.4 (0.2) 4.6 (0.2) 4.6 (0.2) 4.9 (0.4) 5.5 (0.2) 5.3 (0.5)
Soil P (mg) 408 (20.1) 536 (66.3) 648 (30.7) 662 (53.8) 716 (31.5) 918 (46.5)
Biomass C_CFE (mg) 1.33 (0.13) 1.52 (0.10) 1.52 (0.20) 1.67 (0.37) 1.89 (0.14) 1.76 (0.45)
Biomass C_SIR (mg) 1.34 (0.13) 1.70 (0.20) 1.73 (0.21) 1.76 (0.19) 1.86 (0.11) 1.77 (0.18)
Biomass N (μg) 181 (28.0) 223 (35.8) 255 (21.3) 265 (40.6) 300 (14.4) 263 (28.1)
Biomass P (μg) 79.0 (12.4) 118 (12.0) 113 (17.7) 127 (24.5) 148 (7.6) 160 (26.2)
DOC (μg) 125 (5.4) 105 (3.5) 107 (3.7) 105 (2.5) 101 (5.0) 97.0 (4.7)
NH4+-N (μg) 3.65 (0.37) 3.24 (0.49) 2.76 (0.35) 2.48 (0.20) 2.51 (0.27) 2.80 (0.23)
NO3--N (μg) 19.6 (2.86) 14.5 (2.04) 16.2 (1.51) 16.0 (2.70) 15.1 (2.1) 14.8 (1.56)
PO4+-P (μg) 8.2 (1.68) 22.0 (2.85) 27.8 (5.21) 31.6 (4.01) 44.8 (4.34) 78.9 (13.29)
  1. pH and C, N and P contents of soils and the soil microbial biomass (in kg−1 soil) in a long-term P-fertilisation trial. Soils received 0, 15 or 30 kg P ha−1 starting in 1968 (0_, 15_, 30_) and 0, 5, 15 or 30 kg P ha−1 since 1999 (_0, _5, _15, _30). See text for details. Microbial biomass was measured by chloroform-fumigation extraction (CFE) or substrate-induced respiration (SIR). DOC is dissolved organic carbon. Data are means, n = 6, with standard error in parentheses.