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Multi-level assessment of soil quality – linking reductionistic and holistic methodologies

Schjønning, Per; Munkholm, Lars J.; Debosz, Kasia and Elmholt, Susanne (2000) Multi-level assessment of soil quality – linking reductionistic and holistic methodologies. In: Elmholt, Susanne; Stenberg, Bo; Grønlund, Arne and Nuutinen, V. (Eds.) DIAS Report, Danish Institute of Agricultural Sciences, 38, pp. 43-52.

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Summary

Soil quality is often used as a qualitative, general term. However, quantification is an important feature of the scientific approach to nature. On the other hand, addressing specific soil parameters as indicators of soil quality includes a reduction of the whole soil system. Therefore, results obtained by specialized methodologies ought to be evaluated by methods integrating the soil characteristics in situ. In this presentation, results are given from an investigation of the tilth of two differently managed loamy soils. One of the soils had been managed for decades with a forage crop system (labeled FCS), which included fertilization with farmyard manure, while the other had been grown with a continuous cereal system (labeled CCS), receiving no input of organic matter. In the field, the structure of the top 30-cm soil layer was described visually (spade analysis) and by studying the fragmentation behavior (soil drop test). Further, the field measurements included determination of soil strength by a torsional shear box method. In the laboratory, shear strength was determined on bulk soil sampled in metal cylinders, and tensile strength was estimated from crushing tests of individual, differently sized aggregates. The FCS soil appeared porous, with crumbs as structural units, while the CCS soil was compact with blocks as structural units. The soil drop test yielded the highest degree of fragmentation for the FCS soil. The torsional shear box method showed the CCS soil to have the highest bulk soil strength. This was confirmed by the laboratory shear annulus method. Finally, the tensile strength measurements revealed a much higher strength of 8-16, 4-8 and 2-4 mm dry aggregates from the CCS soil as compared to the FCS soil, while 1-2 mm aggregates were strongest in the FCS soil. This indicates a higher friability for the FCS soil, which is in accordance with the soil behavior in the field tests. In conclusion, the quality of the FCS soil – as evaluated by its mechanical behavior – was found to be higher than that of the CCS soil. An important result is the good correlation between the integrating field methods and the differentiating laboratory methods. This means that the quantifying, reductionistic scientific approach is not conflicting with the ‘holistic’ descriptions in the field.


EPrint Type:Conference paper, poster, etc.
Type of presentation:Paper
Subjects: Soil > Soil quality
Knowledge management > Research methodology and philosophy
Research affiliation: Denmark > DARCOF II (2000-2005) > I. 7 (ROMAPAC) Soil quality in organic farming
Deposited By: Schjønning, Senior Soil Scientist Per
ID Code:51
Deposited On:03 Oct 2002
Last Modified:12 Apr 2010 07:27
Document Language:English
Status:Published
Refereed:Not peer-reviewed

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