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Nutrient availability affects carbon turnover and microbial physiology differently in topsoil and subsoil under a temperate grassland

Liang, Zhi; Olesen, Jørgen E.; Jensen, Johannes L. and Elsgaard, Lars (2018) Nutrient availability affects carbon turnover and microbial physiology differently in topsoil and subsoil under a temperate grassland. Geoderma, 336, pp. 22-30.

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Document available online at: https://doi.org/10.1016/j.geoderma.2018.08.021


Increasing subsoil organic carbon inputs could potentially mitigate climate change by sequestering atmospheric CO2. Yet, microbial turnover and stabilization of labile carbon in subsoils are regulated by complex mechanisms including the availability of nitrogen (N), phosphorous (P), and sulfur (S). The present study mimicked labile organic carbon input using a versatile substrate (i.e. glucose) to address the interaction between carbon-induced mineralization, N-P-S availability, and microbial physiology in topsoil and subsoils from a temperate agricultural sandy loam soil. A factorial incubation study (42 days) showed that net losses of added carbon in topsoil were constant, whereas carbon losses in subsoils varied according to nutrient treatments. Glucose added to subsoil in combination with N was fully depleted, whereas glucose added alone or in combination with P and S was only partly depleted, and remarkably 59–92% of the added glucose was recovered after the incubation. This showed that N limitation largely controlled carbon turnover in the subsoil, which was also reflected by microbial processes where addition of glucose and N increased β-glucosidase activity, which was positively correlated to the maximum CO2 production rate during incubation. The importance of N limitation was substantiated by subsoil profiles of carbon source utilization, where microbial metabolic diversity was mainly related to the absence or presence of added N. Overall, the results documented that labile carbon turnover and microbial functions in a temperate agricultural subsoil was controlled to a large extent by N availability. Effects of glucoseinduced microbial activity on subsoil physical properties remained ambiguous due to apparent chemical effects of N (nitrate) on clay dispersibility.

EPrint Type:Journal paper
Subjects: Soil > Soil quality > Soil biology
Research affiliation: Denmark > Private funders/foundations > Deep Frontier
Deposited By: Liang, Zhi
ID Code:33793
Deposited On:21 Sep 2018 13:16
Last Modified:21 Sep 2018 13:16
Document Language:English
Refereed:Peer-reviewed and accepted

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