Visualizing the dynamics of soil aggregation as affected by arbuscular mycorrhizal fungi

Abstract

Stable soils provide valuable ecosystem services and mechanical soil stability is enhanced by the presence of arbuscular mycorrhizal fungi (AMF). Soil aggregation, which is the major driver of mechanical soil stability, is often treated as a static phenomenon, even though aggregate turnover is continually ongoing. In fact, some breakdown of macroaggregates is necessary to allow new aggregate formation and inclusion of new organic matter into microaggregates. We determined how aggregate turnover times were affected by AMF by tracking movement of rare earth elements (REE), applied as their immobile oxides, between aggregate size classes, and using X-ray fluorescence microscopy to spatially localize REEs in a sample of aggregates. Here we show that AMF increased large macroaggregate formation and slowed down disintegration of large and small macroaggregates. Microaggregate turnover was increased in the presence of AMF. Internal aggregate organization suggested that although formation of microaggregates by accretion of soil to particulate organic matter is common, it is not the only mechanism in operation.

Root growth and presence of Rhizophagus irregularis distinctly alter substrate hydraulic properties in a model system with Medicago truncatula

“…For AMF, abundant evidence exists for their involvement in the degree of soil aggregation (Leifheit et al 2015(Leifheit et al , 2014Morris et al 2019;Rillig 2004;Rillig et al 2015;Rillig and Mummey 2006;Rillig et al 2002;Tisdall and Oades 1982;Wilson et al 2009;Wright and Upadhyaya 1998). A so-called 'sticky string-bag' function has been assigned to the extraradical mycelium of AMF; acting as a binding agent for soil particles (Miller and Jastrow 2000).…”

Effect of Indigenous and Introduced Arbuscular Mycorrhizal Fungi on Growth and Phytochemical Content of Vegetatively Propagated Prunus africana (Hook. f.) Kalkman Provenances

“…These soil microorganisms help host plants to absorb mineral nutrients such like phosphorus (P), nitrogen (N), sulphur (S), potassium (K), calcium (Ca), iron (Fe), copper (Cu), and zinc (Zn); in return they benefit from the host plants by acquiring organic carbon in form of glucose and lipid [19,20]. In addition to direct nutrient benefits, AMF have been reported to offer ecosystem services, including resistance to diseases like root infections caused by pathogenic fungi [21,22], increased tolerance to drought [23] and improving the soil structure with the aggregate formation [24][25][26]. These benefits contribute to the growth and adaptation of plants in diverse environmental conditions.…”

Rhizosphere priming effects in soil aggregates with different size classes

“…, Morris et al. ), our results suggests that the final impact of living roots on aggregate dynamics depends on aggregate size class, which differs in stability, porosity, and density (Materechera et al. , De Gryze et al.…”

“…4). As the effect of living roots on aggregate dynamics is mixed with formation, stabilization, and destruction (Six et al 2004, Morris et al 2019, our results suggests that the final impact of living roots on aggregate dynamics depends on aggregate size class, which differs in stability, porosity, and density (Materechera et al 1994, De Gryze et al 2005. The reduced destruction of SMA in the SMA treatment by planting (Fig.…”