1. A large nitrogen supply from the stable mineral-associated soil organic matter fraction.
- Author
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Villarino, Sebastián H., Talab, Emir, Contisciani, Luciano, Videla, Cecilia, Di Geronimo, Paula, Mastrángelo, Matias E., Georgiou, Katerina, Jackson, Robert B., and Piñeiro, Gervasio
- Subjects
ORGANIC compounds ,ROTATIONAL grazing ,RANGE management ,NITROGEN cycle ,NITROGEN ,MINERALIZATION - Abstract
Soil organic matter (SOM) mineralization and nitrogen (N) release are key biogeochemical processes for which the relative contribution of particulate (POM) and mineral-associated organic matter (MAOM) fractions is poorly understood. MAOM is generally considered to be a more stable fraction that contains most of the soil organic N, whereas POM is more readily decomposable and contains less N. Here, we measured variations in the potentially mineralizable N from each SOM fraction across three contrasting land-uses (forest, pasture, and croplands) and two different grazing managements (rotational and continuous grazing). Contrary to expectations, we found that the MAOM fraction consistently supplied more N than the POM fraction during SOM mineralization in all land-uses evaluated. Across our environmental gradient, potentially mineralizable N from POM increased with the carbon (C) concentration and C/N ratio of POM, while potentially mineralizable N from MAOM increased with the C concentration of MAOM but decreased with clay content. Our work suggests that MAOM contributions to short-term N mineralization and N supply to plants have been undervalued. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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