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Interactions between soil related sciences - Linking geophysics, soil science and digital soil mapping

Periodic Report Summary - ISOIL (Interactions between soil related sciences - Linking geophysics, soil science and digital soil mapping)

A major prerequisite for the protection and restoration of soils is the availability of high-resolution soil property maps. Conventional, sample-based soil property mapping is time-consuming, cost-intensive, and the data collected are available only for discrete. Various soil parameters can already be mapped using rapid, nearly non-destructive methods. However, current techniques are deficient in terms of reliability and precision, the understanding of relationships between mapped soil parameters and relevant soil functions, the potential for upscaling to investigate large areas and the evaluation of soil degradation at such scales.

The ISOIL project integrates the following main components:
(i) high resolution, non-destructive geophysical and spectroscopic methods,
(ii) mapping and modelling concepts of digital soil mapping (DSM) and pedometrics,
(iii) optimised soil sampling with respect to profound soil scientific and (geo)statistical strategies.

The objectives of ISOIL are the development of new, and the improvement of existing methods for spatial soil mapping including geophysical, spectroscopic and monitoring techniques. ISOIL will develop, validate and evaluate necessary concepts and strategies for transferring measured physical parameter distributions into such spatial maps.

Main results of the first reporting period

The comparability of data of different sensor types, as well as the reproducibility of data, cannot be taken for granted. One prerequisite for further data analysis is the qualitative and quantitative comparison of different geophysical properties. Reproducibility is one of the most important conditions for monitoring tasks. A special focus in mobile sensing was put on electromagnetics, ground penetrating radar, magnetics and gamma-spectroscopy, since a combination of these methods seems highly promising for soil sensing. All measurements are accompanied by sample-based soil mapping to determine and derive site-specific coefficients of geophysical transfer functions (GPTFs) in the lab. Field sites are characterised by very different soil types. We compared sensor types, performed analyses of data quality, improved and tested emerging techniques, developed GPTFs at the field and collected samples for lab analyses. Trial GPTFs have been developed, linking geoelectrical and dielectric measurements, and for the description of spectral induced polarisation spectra. We are working on pore-scale and pore-network models that can be used to derive links between soil parameters and geophysical responses.

We apply a hierarchical mapping approach with geophysical overview mapping, mapping of selected sub-plots with dense grids and point based measurements, as well as soil sampling for laboratory analysis according to newly developed DSM approaches. Weighted latin hypercube sampling, as developed by ISOIL, is the first sampling scheme that allows for weighing predictors according to their signal noise ratio in terms of the kriging cross-validation error.

A further key component was the development of guidelines for soil mapping at different scales and the development of guidelines for the use of different methods in the context of soil mapping. During the reporting period the outline of the handbook was fixed and responsibilities were discussed. We started the procedure of the CEN workshop of the European Committee for Standardisation to establish a widely accepted voluntary standard for a best practice of one geophysical method, EMI.

We organised two workshops for stakeholders, decision makers and end- users in Bulgaria and Austria to give an introduction to soil property mapping, geophysical methods and emerging techniques. Since field surveys for the validation of methods will be conducted at the Fuhrberger Feld (Germany) in 2010, local stakeholders had to be informed at an early stage about the project. Therefore, we organised a meeting in June 2009.

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