Table 2.

Correlation coefficients and stepwise regression model between county-level rate of SOC change (SOCrate) and climate (mean annual temperature, MAT; and mean annual precipitation, MAP), initial soil properties (sand, silt, and clay content; soil pH in 1980, pH1980; and SOC stock in 1980, SOC1980), and management practices (cumulative N fertilizer input, NfNinput; and average crop residue carbon input, ResidueCinput) (n = 58)

FactorsClimateInitial soil propertiesManagement practices
MATMAPSandSiltClaySOC1980pH1980NfNinputResidueCinput
Pearson R0.32*0.080.030.03−0.11−0.58***0.010.28*0.45***
Partial R−0.1−0.05−0.070.070.29*−0.57***−0.2−0.060.39***
  • Stepwise regression model. SOCrate(Mg C ha−1 y−1) = 0.13 − 0.009 × SOC1980 (Mg C ha−1) + 0.005 × Clay(%) + 0.16 × ResidueCinput(Mg C ha−1 y−1). Adjusted R = 0.49, P < 0.001. *P < 0.05; ***P < 0.001.