Archiving Samples

Collecting and archiving of soil samples, as well as biological materials including plants, grains, herbage, and manures, has had a long history, going back to the famous Rothamsted Sample Archive (RSA) established by Lawes and Gilbert in 1843. At present, soil archives are maintained by a number of research institutions in various countries, including the Institute of Soil Science of the Chinese Academy of Sciences, the Danish Institute of Agricultural Sciences, the Agricultural Research Service of the United States Department of Agriculture, Alterra (Wageningen), Punjab Agricultural University (India), the Russell Ranch archives (Agricultural Sustainability Institute, University of California at Davis) and the CSIRO National Soil Archive (Australia) [1]. Why are these archives needed? Perhaps one simple justification for their importance may be given as the following: “The Archive’s soil specimens are invaluable “time capsules” for assessing temporal changes in soil properties, particularly as new analytical tools become available.” [2]. Thus, they provide unique opportunities for long-term ecosystem studies [3]. To those archives are applicable the words of Sir John Bennet Lawes, a farmer and businessman, regarding the whole of long-term research at the Rothamsted Experimental Station: “I must explain that the object of these investigations is not exactly to put money into my pocket, but to give you the knowledge by which you may be able to put money into yours” [4]. Here is a short (and certainly very limited) list of the findings and discoveries made using stored soil samples:

• Monitoring plutonium and uranium, following nuclear bomb tests, with ability to identify the precise radiation “signature” of individual explosions, “from the Nevada desert tests of the 1950s.. and from Chernobyl in 1986” [5];
• Long-term trends in iodine and selenium retention in soil and uptake by herbage, “to assess the effect of soil amendments, annual rainfall, crop yield and changes in soil chemistry from 1876 to 2008” [6];
• Establishing that air-dried soils protect microbial DNA for more than 150 years thus suggesting “an invaluable resource for future research” [7];

As well as multiple other findings made based on soils from the RSA [8], such as:

• Quantification of heavy metal contents in soil following sewage sludge application or phosphate fertilizers;
• Determination of contents of polyaromatic hydrocarbons and dioxins, due to the increase of their atmospheric concentrations since the early 1900s;
• Detecting the 1860-2000 changes in atmospheric sulfur deposition with time, by using soil and herbage samples;
• Examination of the effect of sulfur deposition on plant pathogen populations;
• The 1844-2003 DNA monitoring of wheat pathogens in wheat straw samples;
• Developing the RothC model of the soil C turnover adapted to climate change;
• Examination of fungicide resistance in plant pathogens.

Even more examples include monitoring of lead pollution and the examination of the development of antibiotic-resistant bacteria [9]. As noted [10], soil archives provide us opportunities to address the problems and questions that may appear in the future, “even though we do not necessarily know what those questions might be”, as international experience in creating and maintaining the soil archives has already proven.