Soil C[O.sub.2] emission estimated by different interpolation techniques

Soil C[O.sub.2] emissions are highly variable, both spatially and across time, with significant changes even during a one-day period. The objective of this study was to compare predictions of the diurnal soil C[O.sub.2] emissions in an agricultural field when estimated by ordinary kriging and sequential Gaussian simulation. The dataset consisted of 64 measurements taken in the morning and in the afternoon on bare soil in southern Brazil. The mean soil C[O.sub.2] emissions were significantly different between the morning (4.54 µmol [m.sup.-2] [s.sup.-1]) and afternoon (6.24 µmol [m.sup.-2] [s.sup.-1]) measurements. However, the spatial variability structures were similar, as the models were spherical and had close range values of 40.1 and 40.0 m for the morning and afternoon semivariograms. In both periods, the sequential Gaussian simulation maps were more efficient for the estimations of emission than ordinary kriging. We believe that sequential Gaussian simulation can improve estimations of soil C[O.sub.2] emissions in the field, as this property is usually highly non-Gaussian distributed. Keywords Soil respiration * Geostatistics * Ordinary kriging * Sequential gaussian simulation