Temporal changes in soil properties at an upland Scottish site between 1956 and 1997

The aim of this study was to examine the frequency with which soil samples require to be taken in order to determine significant temporal changes in s oil properties. The examination was carried out using data from Glensaugh R esearch Station in north-east Scotland where podzolic soils were sampled in 1956, 1977 and 1997, and by re-analysis of archived material. Significant differences in chemistry due to storage were detected, particularly decreas es in pH of air-dried organic soils. In these cases original data were used for statistical analysis to establish changes between 1956 and 1997. Tempo ral changes were found for exchangeable Ca and Mg which generally decreased with time throughout the soil profile, whereas exchangeable H increased. D erived data, such as percent base saturation, declined dramatically due to decreases in exchangeable base cations. Similar podzolic soils were sampled at an adjacent Environmental Change Network (ECN) site in 1993. Applicatio n of statistical techniques to the ECN soil chemistry data allowed an estim ation of the detectable change between any two years. These data along with the rates of temporal change from 1956 to 1997 allowed the calculation of the number of years required for measurable changes to be achieved. These c hanges and sampling intervals vary among different horizons and chemistries . Although they are site-specific, they do confirm that the current ECN pro tocols of a 5-year and 20-year sampling would be appropriate in order to de tect changes in soil properties over time at this site. (C) 2001 Elsevier S cience B.V. All rights reserved.