Modeling temporal changes in structural stability of a clay loam soil
1992
Caron, J. | Kay, B.D. | Stone, J.A. | Kachanoski, R.G.
Field measurements of short-term changes in structural stability often include an important temporal variability that tends to mask treatment effects. Adequate modeling of this temporal variability is needed to increase precision in treatment comparisons. Previous work has shown that this variability can be related to water content. However, the relationship between structural stability parameters and water content is complex, because different processes linked to water content (slaking, swelling, age hardening) may govern the response of structural stability to a change in water content. This study used a time series analysis approach to describe the complex response or structural stability parameters to water content. Temporal changes in the wet aggregate stability (WAS) and the dispersible clay fraction (DCF) of a clay loam soil under four different cropping histories were modeled using gravimetric water content as an independent variable. The lowest predictability for WAS was observed for soil in bare plots and under continuous corn (Zea mays L.) production. The amount of variability in WAS explained by gravimetric water content increased as the number of years of grasses increased (to a maximum of 3 yr in this study). Regression models indicated that the low predictability of WAS using gravimetric water content observed for bare soils and soils under continuous corn production was improved by including values of the antecedent water content before sampling. The predictability of DCF using gravimetric water content was generally higher than the predictability of WAS, did not include past values of gravimetric water content, and was independent of cropping history.
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