A topic not covered in the recent special Section on Soils: The Final Frontier (11 June, pp. 1613–1637) is the possibility of using modern DNA-based molecular techniques to study microbial diversity in archived soil samples. Like other soil research institutes in countries such as the United Kingdom, the United States, and Switzerland, Alterra, as heir to the Research Institute for Soil Fertility in the Netherlands, has a soils archive with, in our case, 250,000 samples, many of them from field experiments that date as far back as 1879. Most of the samples are well documented. We selected a series of soil samples from the 1950s to 1970s from an experiment that was initiated in 1940 and analyzed time series from two field plots, one from a plot that had received animal manure and another one from a plot that had received chemical fertilizer. Genetic diversity in the archived soil samples was analyzed with 16S-based denaturing gradient gel electrophoresis (PCR-DGGE) of the DNA extracted from the soil. From densitometric profiling and multivariate analysis of the gels, it was clear that the community structure of manure-amended soils is distinct from the community structure of the soil that had received no manure and only mineral fertilizer (see [figure][1]). From this and other results ([1][2]), we conclude that it is possible to detect systematic differences in soil microbial community composition in samples that have been dried and stored for more than 50 years. This opens up the possibility of using historic material in existing soil archives to answer questions on the long-term effects of management and environmental change on soil microbial diversity. ![Figure][3] Pearson correlation analysis of DGGE gels from archived soil samples that had received manure (brown) or inorganic fertilizer (green) since 1940. The year of sampling is as indicated. 1. 1.[↵][4] 1. J. Dolfing, 2. A. Vos, 3. J. Bloem, 4. P. J. Kuikman , “Microbial diversity in archived agricultural soils: the past as a guide to the future (Alterra report 916, Alterra, Wageningen, the Netherlands, 2004) (available at [www.alterra.wur.nl/Internet/Modules/pub/PDFFiles/Alterrarapporten/AlterraRapport916.pdf][5]). [1]: #F1 [2]: #ref-1 [3]: pending:yes [4]: #xref-ref-1-1 "View reference 1. in text" [5]: http://www.alterra.wur.nl/Internet/Modules/pub/PDFFiles/Alterrarapporten/AlterraRapport916.pdf