Siri Svendgård-Stokke

Head of Department

(+47) 478 14 011
siri.svendgard-stokke@nibio.no

Place
Ås O43

Visiting address
Oluf Thesens vei 43, 1433 Ås

Abstract

Dette er en oppstartrapport for NIBIOs bidrag i prosjektet “E2SOILAGRI”. Rapporten sammenfatter informasjon om det latviske jordinformasjonssystemet som framkom gjennom intervjuer med part-nere og interessenter i prosjektet. Arbeidet er definert som underaktivitet 4.1 i Terms of Reference for NIBIOs rolle i prosjektet.

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Abstract

Dette er en rapport som beskriver det norske jordkartleggingsprogrammet. Kjennskap til det norske programmet og de erfaringer som er gjort for bruk av WRB (2014) vil sannsynligvis være nyttig for det latviske arbeidet i prosjektet “E2SOILAGRI”. Arbeidet er definert som underaktivitet 4.1.1 i Terms of Reference for NIBIOs rolle i prosjektet. Summary This is a report which describes the Norwegian Soil Information System. Knowledge on the use and adjustments of the WRB (2014) in Norway, and the experiences which have been encountered, is considered useful for the Latvian work in the project “E2SOILAGRI”. This task is defined as sub-activity 4.1.1 in the Terms of Reference for the NIBIO assignment.

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Abstract

This paper reports soil development over time in different climates, on time-scales ranging from a few thousand to several hundred thousand years. Changes in soil properties over time, underlying soil-forming processes and their rates are presented. The paper is based on six soil chronosequences, i.e. sequences of soils of different age that are supposed to have developed under the similar conditions with regard to climate, vegetation and other living organisms, relief and parent material. The six soil chronosequences are from humid-temperate, Mediterranean and semi-arid climates. They are compared with regard to soil thickness increase, changes in soil pH, formation of pedogenic iron oxides (expressed as Fed/Fet ratios), clay formation, dust influx (both reflected in clay/silt ratios), and silicate weathering and leaching of base cations (expressed as (Ca+Mg+K+Na)/Al molar ratios) over time. This comparison reveals that the increase of solum thickness with time can be best described by logarithmic equations in all three types of climates. Fed/Fet ratios (proportion of pedogenic iron Fed compared to total iron Fet) reflects the transformation of iron in primary minerals into pedogenic iron. This ratio usually increases with time, except for regions, where the influx of dust (having low Fed/Fet ratios) prevails over the process of pedogenic iron oxide formation, which is the case in the Patagonian chronosequences. Dust influx has also a substantial influence on the time courses of clay/silt ratios and on element indices of silicate weathering. Using the example of a 730 ka soil chronosequence from southern Italy, the fact that soils of long chronosequences inevitably experienced major environmental changes is demonstrated, and, consequentially a modified definition of requirements for soil chronosequences is suggested. Moreover, pedogenic thresholds, feedback systems and progressive versus regressive processes identified in the soil chronosequences are discussed.