Both the sinkage and penetration resistances
were negatively correlated with SOC concentration (Fig. 6a,c),
which was in consistent with other reports on penetration
resistance (Laboski et al., 1998; Tarkiewicz and Nosalewicz,
2005). Laboski et al. (1998) and Tarkiewicz and Nosalewicz
(2005) attributed the weak correlations to the effects of soil
moisture and bulk density in thefield. With increasing SOC
concentration, the total porosity after puddling decreased (Fig. 4d).