Sub-sampling a large physical soil archive for additional analyses to support spatial mapping; a pre-registered experiment in the Southern Nations, Nationalities, and Peoples Region (SNNPR) of Ethiopia

A - Papers appearing in refereed journals

Alemu, R., Gelaw, A. M., Gashu, D., Tafere, K., Mossa, A. W., Bailey, E. H., Masters, W. A., Broadley, M. and Lark, R. M. 2022. Sub-sampling a large physical soil archive for additional analyses to support spatial mapping; a pre-registered experiment in the Southern Nations, Nationalities, and Peoples Region (SNNPR) of Ethiopia. Geoderma. 424 (15 Oct), p. 116013. https://doi.org/10.1016/j.geoderma.2022.11601

AuthorsAlemu, R., Gelaw, A. M., Gashu, D., Tafere, K., Mossa, A. W., Bailey, E. H., Masters, W. A., Broadley, M. and Lark, R. M.
Abstract

The value of physical archives of soil material from field sampling activities has been widely recognized. If we want to use archive material for new destructive analyses to support a task, such as spatial mapping, then an efficient sub-sampling strategy is needed, both to manage analytical costs and to conserve the archive material. In this paper we present an approach to this problem when the objective is spatial mapping by ordinary kriging. Our objective was to subsample the physical archive from the Ethiopia Soil Information System (EthioSIS) survey of the Southern Nations, Nationalities and Peoples Region (SNNPR) for spatial mapping of two variables, concentrations of particular fractions of selenium and iodine in the soil, which had not been measured there. We used data from cognate parts of surrounding regions of Ethiopia to estimate variograms of these properties, and then computed prediction error variances for maps in SNNPR based on proposed subsets of the archive of different size, selected to optimize a spatial coverage criterion (with some close sample pairs included). On this basis a subsample was selected. This is a preregistered experiment in that we have proposed criteria for evaluating the success of our approach, and are publishing that in advance of receiving analytical data on the subsampled material from the laboratories where they are being processed. A subsequent short report will publish the outcome. The use of preregistered trials is widely recommended and used in areas of science including public health, and we believe that it is a sound strategy to promote reproducible research in soil science.

KeywordsSoil archive ; Sub-sampling; Selenium; Iodine; Pre-registered experiment; 0000; 2000 MSC; 1111
Year of Publication2022
JournalGeoderma
Journal citation424 (15 Oct), p. 116013
Digital Object Identifier (DOI)https://doi.org/10.1016/j.geoderma.2022.11601
Open accessPublished as ‘gold’ (paid) open access
FunderBill and Melinda Gates Foundation
Biotechnology and Biological Sciences Research Council
Funder project or codeGeoNutrition - tackling hidden hunger in Sub-Saharan Africa
Publisher's version
Output statusPublished
Publication dates
Online28 Jun 2022
Publication process dates
Accepted15 Jul 2022
PublisherElsevier Science Bv
ISSN0016-7061

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