Testing a new method for sequential silicon extraction on soils of a temperate–humid climate

Abstract

The importance of silicon (Si) compounds in agriculture and geochemical cycles has received increasing attention over the last decade; however, quantitative data on non-crystalline pedogenic Si phases in soils are still rare. Recently, the authors developed a method for sequential Si extraction from soils, in order to improve the quantification of different Si compounds in soils. The method has been tested on samples of known composition. Here, the method is applied for the first time to complete soil profiles. Six different soil types from south-west Germany that have developed since the end of the last glacial period were selected. Most of the Si in these soils was bound in primary and secondary silicates. In mineral soil horizons, the second-highest proportion of Si was in precipitates of amorphous silica (minerogenic amorphous silica), whereas in some O horizons, the second-most important Si fraction was in biogenic amorphous silica. Topsoil horizons and clayey subsoil horizons of a Luvisol and a Stagnosol especially accumulate amorphous silica. Silicon from bio-opal contributed up to 14% to the total Si in Oa horizons of the studied soils. The smallest amounts of Si were found in the mobile and adsorbed Si fractions. Some methodological limitations are identified and discussed; however, the new sequential method of Si extraction enabled separation of different Si fractions in typical soils of a temperate-humid climate.

Amorphous silica pools in permafrost soils of the Central Canadian Arctic and the potential impact of climate change

“…This hypothesis is further supported by SEM microscopy, where only a few (wet shrub tundra) to no diatoms and/or phytoliths (moist shrub-, dry shrub-and lichen tundra) were observed in the mineral layer of all the shrub tundra classes. Other studies, applying various techniques to determine ASi storage in soil, support this shift from biogenic Si to pedogenic Si fractions with depth (Saccone et al 2007;Sommer et al 2013;Georgiadis et al 2014;Blecker et al 2006;Cornelis et al 2014). However, some of the ASi in the mineral layer may be of biogenic origin since ASi can be translocated downward the soil profile (Fishkis et al 2010) through the process of e.g.…”

Estimated storage of amorphous silica in soils of the circum‐Arctic tundra region

“…Although still present, diatoms and phytoliths appeared more scarce and fragmented in deeper mineral horizons. Other studies, applying different techniques to quantify ASi, support this shift from a dominance of biologically formed ASi in the top (organic) soil toward a dominance of pedogenic ASi with depth [ Barão et al ., , ; Georgiadis et al ., ; Sommer et al ., ; White et al ., ].…”

“…When compared to other methods [ Barão et al ., , ; Meunier et al ., ], the Na 2 CO 3 extraction method has proven to be reliable for determination of ASi of biogenic origin in fresh vegetation material and top organic soils. In deeper mineral soils, pedogenic fractions and partial dissolution of clays may contribute significantly to the ASi pool extracted [ Barão et al ., , ; Georgiadis et al ., ].…”

Review Article. What are the nature and formation conditions of hydroxy‐interlayered minerals (HIMs) in soil?

“…In contrast, Niederbudde and Kussmaul () reported a ‘degree of chloritization' of 48% for the clay fraction of an E horizon (pH 3.8) and of 39% for the clay fraction of an Ah horizon (pH 4.5) in a forested Luvisol developed from loess. Georgiadis et al () found the largest proportions of HIMs in acidic organic and mineral topsoil horizons of Podzols developed from sandstone in the Black Forest (Germany). However, their occurrence is not necessarily the consequence of their recent formation, as they might be remnants of earlier stages of soil formation ( Blum , ).…”