Carbon sequestration in aggregates from native and cultivated soils as affected by soil stoichiometry
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ORIGINAL PAPER
Carbon sequestration in aggregates from native and cultivated soils as affected by soil stoichiometry Ruqin Fan 1 & Jianjun Du 1 & Aizhen Liang 2 & Jun Lou 3 & Jiangye Li 1 Received: 1 March 2020 / Revised: 30 June 2020 / Accepted: 2 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Quantitative influence and underlying mechanisms of nutrient stoichiometry on mineralization of native Soil organic C (SOC) and straw C in different aggregate classes from cultivated and non-cultivated soils are still unclear. Soil samples (Mollisols) from a native woodlot and a farmland converted from woodlot were sieved into three aggregate classes (mega-aggregates (6.3-2 mm), macro-aggregates (2-0.25 mm), and micro-aggregates (< 0.25 mm)) and incubated (180 days) under different nutrient rates (nil, low, and high supplies of N and P) with or without 13C-enriched straw amendment. Significantly higher percentage of native SOC was mineralized from mega- and macro-aggregates (65.8-82.2%) compared with micro-aggregates (48.3-52.0%) in woodlot soil. Nutrient addition significantly increased aggregate-associated C in both soils with straw, and the increase was greater in farmland than in woodlot soil and in large-sized aggregates than in micro-aggregates. These results suggested that large aggregates serve as a C reservoir of labile C, while micro-aggregates that contained C was not easily mineralized even with abundant nutrients. Differences of C mineralization among aggregate size classes were significant in woodlot soil but not in farmland soil. Depletion of SOC was greater with increasing nutrient addition rates in farmland aggregates without straw, while the depletion in woodlot aggregates showed no difference among nutrient treatments, suggesting that microbial activity was nutrient-limited in farmland aggregates. The results improved our knowledge on SOC mineralization in response to residue-nutrient management in different aggregate classes from cultivated and non-cultivated soils, which have important implications for strategies to improve soil fertility or mitigate climate change via increased SOC. Keywords Soil organic C . Aggregates . Straw incorporation . Stoichiometry . Land use . 13C isotope
Introduction
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00374-020-01489-2) contains supplementary material, which is available to authorized users. * Jiangye Li [email protected] 1
Engineering and Technology Research Center for Agricultural Land Pollution Prevention and Control of Guangdong Higher Education Institutes, College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
2
Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
3
Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province College of Life Sciences, Huzhou University, Huzhou 313000, China
Soil organic C (SOC) sequestration depends on the increase
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