TEMPORAL PERSISTENCE OF SPATIAL PATTERNS FOR MINERALIZABLE NITROGEN AND SELECTED SOIL PROPERTIES

To assist N-fertilization planning and to avoid N-pollution problems, an evaluation of soil N-mineralization ability is imperative. In addit ion to the accuracy of that evaluation under laboratory conditions, kn owledge of its spatial and temporal variation is helpful for further d ata analyses. This study aimed to characterize the spatial variation o f soil mineralizable N, to investigate its spatial relation with rive basic soil properties (oxidizable C, pH, electrical conductivity, exch angeable NH4+, and gravimetric water content), and to examine the chan ges in the spatial patterns and correlation structures during the wint er. In October and April 1989, 73 samples were collected from spots 1 to 57 m apart in a long-term fallow plot. Nitrogen-mineralization abil ity was measured through an anaerobic incubation experiment. The study of scale-dependent correlation structures and spatial patterns was ca rried out through a multivariate geostatistical analysis. The mean and standard deviation of most properties studied changed slightly during the winter. Nitrogen-mineralization ability was mainly explained by t he amount of oxidizable C, which appeared to be well correlated with g ravimetric water content. The spatial structure of all soil properties measured was characterized by large variation at small distances (< 1 m) and by the independence of the observations beyond 12 m. In additi on, most of the spatial patterns showed a temporal persistence, i.e., high and low values generally occurred at the same locations before an d after winter.