Saving the face of soil aggregates

Abstract

Hierarchy levels and building units of micro‐ and macroaggregates and related separation methods. The hierarchy levels (left arrow) are inversely related to the energy necessary for the disruption (right arrow).

The effects of long-term fertilizations on soil hydraulic properties vary with scales

“…This is also corroborated by recent findings that soil physical properties affected soil carbon and nitrogen more than soil enzymes and microbial communities ( Li et al, 2020 ). Understanding the multiscale soil structural alteration instigated by agricultural practice change is hence important as pores at different scales play different roles in hydrological and biogeochemical functions ( Wang et al, 2019 , Yudina and Kuzyakov, 2019 ).…”

Bypass and hyperbole in soil research: Worrisome practices critically reviewed through examples

“…In a matter of minutes to just a few hours depending on the desired resolution, one can characterize the geometry of the visible pore space in small undisturbed soil samples. Contrary to allegations made by several staunch defenders of the aggregate concept (Wang et al, 2019b; Yudina & Kuzyakov, 2019), it is in general impossible to identify aggregates in 3D CT images of soil samples, even in the case of columns filled with artificially repacked aggregates. Nevertheless, mathematical techniques exist, and novel ones are continuously being developed, to quantify the geometry of the pore space and account for it explicitly in computer models of soil dynamics, making unnecessary any mention of aggregates (e.g., Houston et al, 2017; Rabot, Wiesmeier, Schlüter, & Vogel, 2018; San José Martínez, Martín, & García‐Gutiérrez, 2018; Vogel & Roth, 2001; Vogel, Weller, & Schlüter, 2010).…”

“…One example of such a process is readily apparent in the literature on soil structure, a concept that most authors in and out of soil science have equated for decades with the presence of soil “aggregates”. These aggregates and their stability have been the object of tremendous attention in the past (e.g., Chevallier, Blanchart, Albrecht, & Feller, 2004; Denef et al, 2001; Remusat et al, 2012; Six et al, 2001; Six, Bossuyt, Degryze, & Denef, 2004; Tisdall & Oades, 1982; Tufano et al, 2009) and have seen a significant upsurge of interest in the last few years, especially in relation to carbon storage in soils (e.g., Ebrahimi & Or, 2016; Gyawali & Stewart, 2019; Márquez, García, Schultz, & Isenhart, 2019; Schweizer, Bucka, Graf‐Rosenfellner, & Kögel‐Knabner, 2019; Totsche et al, 2017; Wang, Brewer, Shugart, Lerdau, & Allison, 2019a, 2019b; Wang, Fonte, Parikh, Six, & Scow, 2017; Yudina & Kuzyakov, 2019). In the past year alone, several workshops and conference sessions, as well as special issues of scholarly journals, have been devoted to soil aggregates.…”

KEYLINK: towards a more integrative soil representation for inclusion in ecosystem scale models. I. review and model concept

“…The accessibility of SOM to microbes due to pore size and the capacity of microbes to oxidize SOM based on the strength of the organo-mineral associations are two different mechanisms involved in SOM stabilization and SOM dynamics. However, the separation of OM occluded in clay microstructures from “true” organo-mineral associations remains a methodological challenge ( Chenu & Plante, 2006 ; Von Lützow et al, 2008 ; Yudina & Kuzyakov, 2019 ). Until this is possible, it might be possible to view organic matter stabilized in organo-mineral associations as in such close contact to the mineral that there is no space for microbes and microbial exoenzymes to physically reach the OM.…”

“… Abramoff et al (2018) proposed to model mineral-associated organic matter (MAOM) and aggregate C as two separate measurable pools but did not actually propose how would they be analytically distinguished. Despite these advances, aggregate formation modelling remains a difficult issue at the stand scale because many of the processes occur at a much smaller scale ( Yudina & Kuzyakov, 2019 ).…”