TY - JOUR
T1 - Organic amendments stimulate co-precipitation of ferrihydrite and dissolved organic matter in soils
AU - Wen, Yong Li
AU - Guo, Xiao Yu
AU - Cheng, Lu
AU - Yu, Guang Hui
AU - Xiao, Jian
AU - He, Xin Hua
AU - Goodman, Bernard A.
PY - 2021/11/15
Y1 - 2021/11/15
N2 - Ferrihydrite-organic matter (OM) complexes in soil play a vital role in preserving soil organic carbon (C), either through adsorption (reaction of OM with existing ferrihydrite) or co-precipitation (neo-formation of ferrihydrite in the presence of OM). However, there is still limited understanding of the effects of long-term fertilization on the pathways for the formation of ferrihydrite-OM in soil. In this study, the dissolved OM (DOM) extracted from a Ferralic Cambisol under 25-year inorganic nitrogen (N), phosphorus (P) and potassium (K) (NPK) or NPK plus organic pig manure (NPKM) was used to synthesize adsorption complexes and co-precipitates. Compared with the adsorption, the co-precipitation of ferrihydrite and DOM resulted in higher C/Fe ratios in the solid products, particularly under NPKM. Analysis of the iron K-edge X-ray absorption near-edge fine structure (XANES) showed that there was a preference for DOM from soil under NPKM treatment to co-precipitate with ferrihydrite, whereas adsorption of ferrihydrite on DOM was more likely with the long-term NPK fertilized soil. Fourier-transform infrared (FTIR) spectra suggested that a higher intensity of Si-O functional groups, clay minerals, and aromatic groups in the DOM from the NPKM treatment played important roles in the co-precipitation process. Desorption of co-precipitated OM was lower than that of adsorbed OM in soils, indicating a higher chemical stability of OM in the co-precipitates. In summary, our results demonstrate that 25-year long-term NPK and NPKM fertilizations have contrasting effects on the formation pathway of ferrihydrite-OM complexes. Organic amendments can stimulate the co-precipitation of DOM and ferrihydrite in soil, leading to greater biological C preservation than the adsorption process, and a further enhancement of long-term SOC protection.
AB - Ferrihydrite-organic matter (OM) complexes in soil play a vital role in preserving soil organic carbon (C), either through adsorption (reaction of OM with existing ferrihydrite) or co-precipitation (neo-formation of ferrihydrite in the presence of OM). However, there is still limited understanding of the effects of long-term fertilization on the pathways for the formation of ferrihydrite-OM in soil. In this study, the dissolved OM (DOM) extracted from a Ferralic Cambisol under 25-year inorganic nitrogen (N), phosphorus (P) and potassium (K) (NPK) or NPK plus organic pig manure (NPKM) was used to synthesize adsorption complexes and co-precipitates. Compared with the adsorption, the co-precipitation of ferrihydrite and DOM resulted in higher C/Fe ratios in the solid products, particularly under NPKM. Analysis of the iron K-edge X-ray absorption near-edge fine structure (XANES) showed that there was a preference for DOM from soil under NPKM treatment to co-precipitate with ferrihydrite, whereas adsorption of ferrihydrite on DOM was more likely with the long-term NPK fertilized soil. Fourier-transform infrared (FTIR) spectra suggested that a higher intensity of Si-O functional groups, clay minerals, and aromatic groups in the DOM from the NPKM treatment played important roles in the co-precipitation process. Desorption of co-precipitated OM was lower than that of adsorbed OM in soils, indicating a higher chemical stability of OM in the co-precipitates. In summary, our results demonstrate that 25-year long-term NPK and NPKM fertilizations have contrasting effects on the formation pathway of ferrihydrite-OM complexes. Organic amendments can stimulate the co-precipitation of DOM and ferrihydrite in soil, leading to greater biological C preservation than the adsorption process, and a further enhancement of long-term SOC protection.
KW - Adsorption
KW - Co-precipitation
KW - Ferralic Cambisol
KW - Ferrihydrite
KW - Organic amendments
KW - Soil carbon preservation
UR - http://www.scopus.com/inward/record.url?scp=85111858854&partnerID=8YFLogxK
U2 - 10.1016/j.geoderma.2021.115352
DO - 10.1016/j.geoderma.2021.115352
M3 - Article
AN - SCOPUS:85111858854
SN - 0016-7061
VL - 402
JO - Geoderma
JF - Geoderma
M1 - 115352
ER -