Soil Aggregate-Associated Carbon Fraction Dynamics during the Process of Tea (<i>Camellia sinensis</i> L.) Planting in Southern Guangxi, China
Revealing the variation in soil aggregate-associated organic carbon (C<sub>org</sub>) in tea plantations of various planting ages is crucial to shed more light on the accumulation and decomposition of soil C<sub>org</sub> in the tea-planting period. This study measured the co...
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| Autores principales: | , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/81848b545b0d47a282833c8b2391bd20 |
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| Sumario: | Revealing the variation in soil aggregate-associated organic carbon (C<sub>org</sub>) in tea plantations of various planting ages is crucial to shed more light on the accumulation and decomposition of soil C<sub>org</sub> in the tea-planting period. This study measured the concentrations of soil C<sub>org</sub>, active carbon (C<sub>act</sub>), and recalcitrant carbon (C<sub>rec</sub>) in different-sized aggregates obtained from tea plantations of various planting ages (8, 17, 25, and 43 years old) at the soil depths of 0–20 and 20–40 cm in southern Guangxi, China. According to the wet-sieving approach, soil aggregates were classified as macro- (>0.25 mm) and micro- (<0.25 mm) aggregates, and the former were further divided into coarse (>2 mm), medium (2–1 mm), and fine (1–0.25 mm) fractions. Based on the mean weight diameter (MWD), the stability of soil aggregates was the highest in the 17-year-old tea plantations, and it was closely related to the concentration of soil C<sub>act</sub> (0–20 cm: R<sup>2</sup> = 0.9744, <i>p</i> < 0.05; 20–40 cm: R<sup>2</sup> = 0.8951, <i>p</i> < 0.05), but not C<sub>org</sub> (0–20 cm: R<sup>2</sup> = 0.1532, <i>p</i> > 0.05; 20–40 cm: R<sup>2</sup> = 0.4538, <i>p</i> > 0.05), during the tea-planting process. In the 0–20 and 20–40 cm soil layers, the coarse and medium macro-aggregates had higher concentrations of C<sub>org</sub>, C<sub>act</sub>, and C<sub>rec</sub>, regardless of the tea-planting age; meanwhile, the soil C<sub>act</sub>/C<sub>rec</sub> ratio, indicating the C<sub>org</sub> availability, increased as aggregate size increased, implying that the soil C<sub>org</sub> was younger and more labile in coarse macro-aggregates relative to finer aggregates. Moreover, the tea-planting age significantly affected the C<sub>org</sub>, C<sub>act</sub>, and C<sub>rec</sub> reserves in both soil layers. To be specific, continuous tea planting facilitated the accumulation of soil C<sub>org</sub> and C<sub>rec</sub>, but their reserves’ increase rates decreased over time; meanwhile, the soil C<sub>act</sub> reserve increased during the early (from 8 to 17 years) tea-planting stage and later decreased. Therefore, during the middle (from 17 to 25 years) and late (from 25 to 43 years) tea-planting stages, maintaining the soil as an C<sub>act</sub> pool plays a vital role in facilitating the formation and stabilization of soil aggregates in southern Guangxi, China. |
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