Understanding Spatio-temporal Patterns of Soil Moisture at the Field Scale

Spatial patterns of soil moisture across a field seem to exhibit some degree of temporal stability, which has been proved to be related to such invariant attributes as topography and soil characteristics. However, how these patterns and locations might be predicted from these attributes is not well understood. Motivated by a desire to understand these relationships, the objective of this study is to determine how elevation relates to underlying stable and consistent moisture patterns. The characteristics of temporal stability of soil moisture across the field have been analyzed during the 2004 and 2005 growing seasons for a 10-ha field near Ames, IA. Ordinary Kriging (OK) and kriging with external drift (KED) have been used as interpolation tools to estimate the spatial pattern of soil moisture across the field in each observing date. Temporally stable locations can be used to accurately predict the field mean soil moisture. Also, kriging predictions of soil moisture on unsampled locations using OK and KED have no significant differences in the predicted soil moisture surfaces, but on their standard error of prediction.