Soil Archiving

The standard practice of description of soil profiles and sampling of soils is done based on soil augerings or in soil pits. Physical soil samples may be taken for analysis in the laboratory which yields data for interpretation and storage in databases/soil information systems. In some cases, additional material is collected for future reference and/or for educational purposes. Physical soil sample archiving itself is the organized storage of sampling material (lab samples), soil specimens, soil documents and reports relevant to the (digital) data in the SIS. Soil archiving follows the soil laboratory analysis in the development of the SIS.

A soil sample represents a specimen of soil at a specific moment in time, a particular location, and a specific depth (range) from the surface. Soil sampling involves, among others, planning, human effort, travel, and laboratory analysis and is therefore expensive. It is not possible to take the same sample again because of the extractive nature of sampling and since soils change in time and space, it is often not possible to take a comparable sample later. Archiving physical soil material allows comparative analysis on various aspects, such as laboratory measurement method and calibration, land management impact, variation in time and space. Also, a soil archive may provide a reference for research, classification, and mapping of soils. Bergh et al. (2022) state that soil archives preserve a snapshot of soils from a specific time and location, allowing researchers to re-evaluate soils of the past in the context of the present for an improved understanding of long-term soil change (see for instance Karssies and Wilson, 2015). Many soil centers manage a soil archive for future research and reference.

Soil archives are often part of governmental organizations, experimental stations and research organizations for long-term research goals and policy related questions. Building and maintaining an archive requires investment in labor and facilities that does not fit the business case of commercial laboratories. A second limitation for commercial laboratories is that the samples are property of the clients that request analyses and consent may not be provided for storage or other uses of the sample. This is also clear when we look at the examples of national and international soil archives in table 5.1 and 5.2. The exception for commercial laboratories may be samples for quality control, calibration, and development of new measurement methods, for example building spectral libraries on samples that were analyzed with chemical and physical laboratory methods (Reijneveld et el., 2022).

Berg et al. (2022) made a literature review of soil archives and found that the age of soil archives across their compilation ranged from 5 to 160 years old, with mean and median archive ages of 48 and 37 year, respectively. Reliance on younger soil archives in publications was much more common, with the 25–34-year archive age range used most frequently for investigating long-term soil change. They conclude that soil archive use has increased since 1980.

This workflow step focuses on physical soil (data) archiving, while chapter 6 describes digital soil (data) archiving. Physical specimens can be documents or objects (soil samples, sampling materials, thin sections, soil monoliths, hand pieces).