TY - JOUR
T1 - Iron speciation in organic matter fractions isolated from soils amended with biochar and organic fertilizers
AU - Giannetta, Beatrice
AU - Plaza, César
AU - Siebecker, Matthew G.
AU - Aquilanti, Giuliana
AU - Vischetti, Costantino
AU - Plaisier, Jasper R.
AU - Juanco, Miguel
AU - Sparks, Donald L.
AU - Zaccone, Claudio
N1 - Publisher Copyright:
© 2020 American Chemical Society.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020
Y1 - 2020
N2 - The role and distribution of iron (Fe) species in physical soil fractions have received remarkably little attention in field-scale systems. Here, we identify and quantify the Fe phases into two fractions (fine sand, FSa, and fine silt and clay, FSi + Cl), isolated from an agricultural soil unamended and amended with different organic materials, by Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The linear combination fitting and wavelet transform of EXAFS data revealed noticeable differences between unamended FSa and FSi + Cl fractions. Specifically, the FSi + Cl fraction was mainly characterized by ferrihydrite (48%) and Fe(III)-soil organic matter (SOM) complexes (37%), whereas in the FSa fraction, ferrihydrite still represented a major phase (44%), with a lower contribution from Fe(III)-SOM (18%). In the FSa fraction, the addition of the organic amendments resulted in an increase of Fe-SOM complexes (31-35%) and a decrease of ferrihydrite (28-29%). By contrast, in the amended FSi + Cl fractions, the added organic matter led to negligible changes in percent ferrihydrite. Therefore, regardless of the amendment type, the addition of organic matter to soil increased the capability of the coarse fraction (FSa) to stabilize organic carbon, thus pointing out that the role of FSa in carbon sequestration in agricultural soils at a global scale may be overlooked.
AB - The role and distribution of iron (Fe) species in physical soil fractions have received remarkably little attention in field-scale systems. Here, we identify and quantify the Fe phases into two fractions (fine sand, FSa, and fine silt and clay, FSi + Cl), isolated from an agricultural soil unamended and amended with different organic materials, by Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The linear combination fitting and wavelet transform of EXAFS data revealed noticeable differences between unamended FSa and FSi + Cl fractions. Specifically, the FSi + Cl fraction was mainly characterized by ferrihydrite (48%) and Fe(III)-soil organic matter (SOM) complexes (37%), whereas in the FSa fraction, ferrihydrite still represented a major phase (44%), with a lower contribution from Fe(III)-SOM (18%). In the FSa fraction, the addition of the organic amendments resulted in an increase of Fe-SOM complexes (31-35%) and a decrease of ferrihydrite (28-29%). By contrast, in the amended FSi + Cl fractions, the added organic matter led to negligible changes in percent ferrihydrite. Therefore, regardless of the amendment type, the addition of organic matter to soil increased the capability of the coarse fraction (FSa) to stabilize organic carbon, thus pointing out that the role of FSa in carbon sequestration in agricultural soils at a global scale may be overlooked.
UR - http://www.scopus.com/inward/record.url?scp=85080092008&partnerID=8YFLogxK
U2 - 10.1021/acs.est.0c00042
DO - 10.1021/acs.est.0c00042
M3 - Article
C2 - 32182047
AN - SCOPUS:85080092008
VL - 54
SP - 5093
EP - 5101
JO - Environmental Science and Technology
JF - Environmental Science and Technology
SN - 0013-936X
IS - 8
ER -