Synergistic relationships between the age of soil organic matter, Fe speciation, and aggregate stability in an arable Luvisol. Siebers, N., Voggenreiter, E., Joshi, P., Rethemeyer, J., & Wang, L. Journal of Plant Nutrition and Soil Science, 187(1):77–88, February, 2024.
Synergistic relationships between the age of soil organic matter, Fe speciation, and aggregate stability in an arable Luvisol [link]Paper  doi  abstract   bibtex   
Abstract Background Knowledge of soil aggregate formation and stability is essential, as this is important for maintaining soil functions. Aims This study aimed to investigate the influence of organic matter (OM), the content of pedogenic iron (Fe) (oxyhydr)oxides, and aggregate size on the stability of aggregates in arable soil. Methods To this end, the Ap and Bt horizons of a Luvisol were sampled after 14 years of bare fallow, and the results were compared with a control field that had been permanently cropped. Results In the Ap horizon, bare fallow decreased the median diameter of the 53–250 µm size fraction by 26%. Simultaneously, the mass of the 20–53 µm size fraction increased by 65%, indicating reduced stability—particularly of larger soil microaggregates—due to the lack of input of fresh OM. The range of 14 carbon ( 14 C) fraction of modern C (F 14 C) under bare fallow was between 0.50 and 0.90, and thus lower than the cropped site (F 14 C between 0.75 and 1.01), which is particularly pronounced in the smallest size fraction, indicating the presence of older C. This higher stability and the reduced C turnover in \textless20 µm aggregates is probably also due to having the highest content of poorly crystalline Fe (oxy)hydroxides, compared to the other size fractions, which act as a cementing agent. Colloid transport from the Ap to the Bt horizon was observed under bare fallow treatment. Conclusions The lack of input of OM decreased the stability of microaggregates and led to a release of mobile colloids, the transport of which can initiate elemental fluxes with as‐yet unknown environmental consequences.
@article{siebers_synergistic_2024,
	title = {Synergistic relationships between the age of soil organic matter, {Fe} speciation, and aggregate stability in an arable {Luvisol}},
	volume = {187},
	issn = {1436-8730, 1522-2624},
	url = {https://onlinelibrary.wiley.com/doi/10.1002/jpln.202300020},
	doi = {10.1002/jpln.202300020},
	abstract = {Abstract
            
              Background
              Knowledge of soil aggregate formation and stability is essential, as this is important for maintaining soil functions.
            
            
              Aims
              This study aimed to investigate the influence of organic matter (OM), the content of pedogenic iron (Fe) (oxyhydr)oxides, and aggregate size on the stability of aggregates in arable soil.
            
            
              Methods
              To this end, the Ap and Bt horizons of a Luvisol were sampled after 14 years of bare fallow, and the results were compared with a control field that had been permanently cropped.
            
            
              Results
              
                In the Ap horizon, bare fallow decreased the median diameter of the 53–250 µm size fraction by 26\%. Simultaneously, the mass of the 20–53 µm size fraction increased by 65\%, indicating reduced stability—particularly of larger soil microaggregates—due to the lack of input of fresh OM. The range of
                14
                carbon (
                14
                C) fraction of modern C (F
                14
                C) under bare fallow was between 0.50 and 0.90, and thus lower than the cropped site (F
                14
                C between 0.75 and 1.01), which is particularly pronounced in the smallest size fraction, indicating the presence of older C. This higher stability and the reduced C turnover in {\textless}20 µm aggregates is probably also due to having the highest content of poorly crystalline Fe (oxy)hydroxides, compared to the other size fractions, which act as a cementing agent. Colloid transport from the Ap to the Bt horizon was observed under bare fallow treatment.
              
            
            
              Conclusions
              The lack of input of OM decreased the stability of microaggregates and led to a release of mobile colloids, the transport of which can initiate elemental fluxes with as‐yet unknown environmental consequences.},
	language = {en},
	number = {1},
	urldate = {2024-11-15},
	journal = {Journal of Plant Nutrition and Soil Science},
	author = {Siebers, Nina and Voggenreiter, Eva and Joshi, Prachi and Rethemeyer, Janet and Wang, Liming},
	month = feb,
	year = {2024},
	pages = {77--88},
}

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