Influence of non‐crystalline minerals in the total amount, resilience and molecular composition of the organic matter in volcanic ash soils (Tenerife Island, Spain)

Abstract

The influence of short‐range ordered minerals, especially allophane or ferrihydrite, in the total amount, resilience and molecular structure of the soil organic matter (SOM) was determined in a series of volcanic ash soils from Tenerife Island (Spain), with a range of amorphous minerals, organic carbon (C) and clay minerals. Up to 120 main analytical descriptors of the SOM were processed by uni‐ and multivariate statistical analyses. Short‐range ordered minerals were estimated from the (Alo + ½ Feo) index, organo‐metallic complexes were calculated from the Alp:Alo ratio and crystalline minerals were determined by X‐ray diffraction. The humic acids (HAs) were isolated, purified and analysed by visible, infrared and 13C nuclear magnetic resonance spectroscopy and analytical pyrolysis. In addition, CO2 release curves from whole soil samples were used to obtain indices of SOM resilience. The results revealed that the amount and resilience of the SOM depended on the presence of short‐range ordered minerals: the greater the content of non‐crystalline minerals, the greater the C stabilization. However, no significant relationships were found between these amorphous minerals and aromatic compounds, which are indicators of resilience in HAs. Conversely, certain molecular characteristics of the HAs, such as the optical density at 465 nm, the concentration of quinone‐type fungal pigments, the yields of carbohydrate‐derivatives and N‐compounds, highlighted the role of allophane‐sized nanoparticles in the protection of microbial metabolites produced during the decomposition, and are also likely to provide active sites for soil C stabilization at the colloidal scale.

Batjes, N. H. 1996. Total carbon and nitrogen in the soils of the world. European Journal of Soil Science, 47, 151‐163. Commentary on the impact of Batjes (1996): by P.J. Loveland, F. Conen & B. van Wesemael

“…Tonneijck et al () found that volcanic soils of the Andes had about twice as much carbon as previously thought and that a significant proportion was stabilized as aluminium (Al)‐complexes. The latter mechanism was also found by Iamarino & Terribile () in Andic soils of the Italian mountains and by Hernández et al () in the soils of Tenerife. However, Scheel et al () attributed the decrease in C mineralization upon increase in soil Al concentration in forest soils to the reduced bioavailablity of C caused by precipitation rather than any toxic effect of the Al at low pH.…”

Effects of fire on soil organic matter quality along an altitudinal sequence on Mt. Etna, Sicily

“…Hernández et al, 2012). However, Hernández et al (2012) found no significant relationships between the amorphous minerals and aromatic compounds. We consequently hypothesise that the dichromate treatment was not able to oxidise all organic fractions that were strongly bound to mineral surfaces.…”

“…Particularly in soils where allophanes are present, potentially easily biodegradable substances are strongly adsorbed or stabilised by complexation processes with amorphous surfaces and, consequently, protected against degradation and oxidation (see e.g. Hernández et al, 2012). However, Hernández et al (2012) found no significant relationships between the amorphous minerals and aromatic compounds.…”

New strategies for submicron characterization the carbon binding of reactive minerals in long-term contrasting fertilized soils: implications for soil carbon storage

“…On the other hand, the reactive mineral surface of organomineral complexes in the complex soil matrix (mainly the topsoil layer) could be greatly improved through organic amendments to soil, such as the anthropogenic importation of organic fertilizers under long-term experimentation (Schmidt et al, 2011;Hernandez et al, 2012;Yu et al, 2012;Wen et al, 2014a;Abdala et al, 2015). Based on a meta-analysis of 49 sites and 130 observations in the world, Maillard and Angers (2014) found that cumulative manure input had a dominant effect on SOC stock changes when compared to no fertilization and chemical fertilization (Maillard and Angers, 2014).…”