TABLE 2

Soil properties in the CO2 gradient experimenta

PropertyValueP value
Sandy loam (Bastsil series)Black clay (Houston series)
ANPP (g/m2)5835370.44
Organic C (%)0.82.7<0.0001
Total C (%)0.95.5<0.0001
Total N (%)0.080.22<0.0001
Organic C/total N10.812.20.0016
Sand (%)60–729–11
Silt (%)20–2636–40
Clay (%)7–1449–55
pH (in H2O)8.097.980.10
  • a P values are from t tests of soil type means; data are from soil samples used in this study. Aboveground net primary production (ANPP) is averaged across the CO2 gradient in 2009. Organic C was measured by combustion at 600°C; total C and N by combustion at 1,050°C. Soil textures are for the upper 50 cm of soil (Table 2 in Fay et al. [24]). Soil pH was measured in July 2009 soil samples and averaged across the CO2 gradient.