TY - JOUR

T1 - Molecular diversity and the fate of biochemical fractions of eucalypt tissues in soil

AU - Almeida, Luís F. J.

AU - Souza, Ivan F.

AU - Hurtarte, Luís C. C.

AU - Teixeira, Pedro P. C.

AU - Inagaki, Thiago M.

AU - Silva, Ivo R.

AU - Mueller, Carsten W.

PY - 2023

Y1 - 2023

N2 - The molecular diversity of the source substrate has been regarded as a significant controller of the proportion of plant material that is either mineralized or incorporated into soil organic matter (SOM). However, quantitative parameters to express substrate molecular diversity remain elusive. In this research, we fractionated leaves, twigs, bark, and root tissues of 13C-enriched eucalypt seedlings into hot water extractables (HWE), total solvent (acetone) extractables (TSE), a cellulosic fraction (CF), and the acid unhydrolyzable residue (AUR). We used 13C NMR spectroscopy to obtain a molecular diversity index (MDI) based on the relative abundance of carbohydrate, protein, lignin, lipid, and carbonyl functional groups within the biochemical fractions. Subsequently, we ob-tained artificial plant organs containing fixed proportions (25%) of their respective biochemical fractions to be incubated with soil material obtained from a Haplic Ferralsol for 200-days, under controlled temperature (25 +/- 1 degrees C) and moisture adjusted to 70-80% of the soil water holding capacity. Our experimental design was a randomized complete block design, arranged according to a factorial scheme including 4 plant organs, 4 biochemical fractions, and 3 blocks as replicates. During the incubation, we assessed the evolution of CO2 from the microcosms after 1, 2, 3, 4, 7, 10, 13, 21, 28, 38, 45, 70, 80, 92, 112, 148, 178 and 200 days from the start of the incubation. After the incubation, soil subsamples were submitted to a density fractionation to separate the light fraction of SOM (LFOM) i.e., with density

AB - The molecular diversity of the source substrate has been regarded as a significant controller of the proportion of plant material that is either mineralized or incorporated into soil organic matter (SOM). However, quantitative parameters to express substrate molecular diversity remain elusive. In this research, we fractionated leaves, twigs, bark, and root tissues of 13C-enriched eucalypt seedlings into hot water extractables (HWE), total solvent (acetone) extractables (TSE), a cellulosic fraction (CF), and the acid unhydrolyzable residue (AUR). We used 13C NMR spectroscopy to obtain a molecular diversity index (MDI) based on the relative abundance of carbohydrate, protein, lignin, lipid, and carbonyl functional groups within the biochemical fractions. Subsequently, we ob-tained artificial plant organs containing fixed proportions (25%) of their respective biochemical fractions to be incubated with soil material obtained from a Haplic Ferralsol for 200-days, under controlled temperature (25 +/- 1 degrees C) and moisture adjusted to 70-80% of the soil water holding capacity. Our experimental design was a randomized complete block design, arranged according to a factorial scheme including 4 plant organs, 4 biochemical fractions, and 3 blocks as replicates. During the incubation, we assessed the evolution of CO2 from the microcosms after 1, 2, 3, 4, 7, 10, 13, 21, 28, 38, 45, 70, 80, 92, 112, 148, 178 and 200 days from the start of the incubation. After the incubation, soil subsamples were submitted to a density fractionation to separate the light fraction of SOM (LFOM) i.e., with density

KW - Proximate analysis

KW - 13C

KW - Substrate biochemistry

KW - 13C-CP

KW - MAS-NMR spectroscopy

KW - Molecular diversity

KW - Microbial respiration

KW - PERFORMANCE LIQUID-CHROMATOGRAPHY

KW - ORGANIC-MATTER FORMATION

KW - STATE C-13 NMR

KW - LITTER DECOMPOSITION

KW - LEAF-LITTER

KW - PLANT

KW - LIGNIN

KW - INPUTS

KW - BIOSYNTHESIS

KW - SPECTROSCOPY

U2 - 10.1016/j.geoderma.2023.116404

DO - 10.1016/j.geoderma.2023.116404

M3 - Journal article

VL - 432

JO - Geoderma

JF - Geoderma

SN - 0016-7061

M1 - 116404

ER -