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|Title:||Accounting for seasonal nitrogen mineralization: an overview|
|Abstract:||Accurately predicting the amount of nitrogen (N) made available for crop use by N mineralization (N-min) of native soil organic matter (SOM) is complicated by different soils, climate, and management, all highly variable from one location to the next. In this paper, we have compiled seasonal estimates of N in from eleven field studies. We only include data for native SOM and do not include organically-amended soils. Initially, the data sets were graphed and regression was performed on the data as is. To further analyze the data, and because different incubation times were used for the different studies, we normalized reported N-min to a twenty-week incubation period. Values of N-min. for a season range between 0.4 and 152 kg N ha(-1) (0.3 and 136 lb N ac(-1)). The average amount of N-min for all of these studies was 49.3 kg N ha(-1) (44 lb N ac(-1)). A graph of Nmin for all of the data against SOM shows a negative relationship. A simple linear fit on that data results in a non significant R-2 of 0.0008. A similar fit of all of the data against total N was also of little value. Eliminating the data collected from short incubations (less than fifteen weeks long) improved the fit; 42% of the variability in normalized twenty-week N-min could be explained by total N. Regression analyses of the total soil N and of SOM content on the seasonal N-min indicated that neither SOM nor total N is a good predictor for the seasonal N-min amount. Soil type, management, and climate at the various locations obviously influence the magnitude of the estimates. More importantly, this review supports the push for an accurate predictive simulation model for seasonal N-min that is non site-specific.|
|Journal Title:||Journal of Soil and Water Conservation|
|Appears in Collections:||North Coast Local Land Services|
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