Spatial variability of nitrogen mineralization at the field scale

TitleSpatial variability of nitrogen mineralization at the field scale
Publication TypeJournal Article
Year of Publication1997
AuthorsMahmoudjafari, M, Kluitenberg, GJ, Havlin, JL, Sisson, JB, Schwab, AP
JournalSoil Science Society of America Journal
Pagination1214 -1221
Accession NumberKNZ00599

Spatial variability of N mineralization represents a potential problem in predicting the quantity of N mineralized under field conditions. An understanding of mineralization variability is needed if prediction of potential mineralization is to be incorporated into fertilizer recommendation models. The objective of this study was to characterize spatial variability of N mineralization in a Kansas agricultural field. Intact undisturbed soil cores were collected at 108 locations within a 1.7-ha field following wheat (Triticum aestivum L.) harvest. The undisturbed cores were incubated aerobically, and NO−3 was leached periodically as a measure of mineralization. Variability was characterized by examining the spatially distributed values of mineralization potential, N0, and mineralization rate constant, k, parameters of the classical first-order mineralization rate model. Values of N0 were distributed normally with low variability (coefficient of variation [CV] = 15%) and weak autocorrelation. Values of k also followed a normal distribution with low variability (CV = 14%) but were spatially independent. Both N0 and k determined the spatial pattern of Nm, the quantity of N mineralized at a particular time. Variability in k controlled the spatial pattern of Nm earlier in the incubation period, and variability in N0 controlled the spatial pattern late in the incubation period. The incubation approach used in this study allowed characterization of the spatial patterns in N0, but the spatial variability of k observed in this study may not adequately represent field conditions because conditions of constant temperature and water content were used.