Podzolisation preserves ichnofossils constructed by ghost shrimp

Martinez, Pedro; Buurman, P.; Lopes-Mazzetto, Josiane Millani; Nascimento, Diego Luciano do; Vidal‐Torrado, Pablo

doi:10.1016/j.catena.2019.04.021

Cited by 4 publications

(1 citation statement)

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“…Bioturbation, also known as the physical displacement of soil materials by organisms, is a key process that influences ecosystem functioning via soil formation (Cosarinsky & Roces, 2007;Johnson et al, 2005;Wilkinson et al, 2009). Bioturbation is also involved in soil aggregation which increases soil porosity and leads to feedback between abiotic and biotic soil components in both the present day and geologic past (Jouquet et al, 2006;Lavelle et al, 2020;Martinez et al, 2019Martinez et al, , 2021. Our data emphasize that Profundihumic Ferralsols contain more bioturbation features (roots and burrows) than Haplic Ferralsols in the first 1 m of the soil profile (Figure 3, Table 1).…”

Section: Organic Matter Accumulation Increases Bioturbationmentioning

confidence: 99%

Organic carbon enables the biotic engineering of beneficial soil structure in Profundihumic and Haplic Ferralsols

Martinez,

Lybrand,

McFarlane

et al. 2023

European J Soil Science

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We investigated how organic matter may, directly and indirectly, modify the porosity of Ferralsols, that is, deeply weathered soils of the tropics and subtropics. Although empirical and anecdotal evidence suggests that organic matter accumulation may increase porosity, a mechanistic understanding of the processes underlying this beneficial effect is lacking, especially so for Ferralsols. To achieve our end, we leveraged the fact that the Profundihumic qualifier of Ferralsols (PF) is distinguished from Haplic Ferralsols (HF) by both a much larger average carbon content in the first 1 m of soil depth (19 kg C m−3 in PF vs. 10 kg C m−3 in HF) and a significantly lower bulk density (1.05 ± 0.08 kg L−1 in PF vs. 1.21 ± 0.05 kg L−1 in HF). Through exhaustive modelling of carbon – bulk density relationships, we demonstrate that the lower bulk density of PF cannot be satisfactorily explained by a simple dilution effect. Rather, we found that bulk density correlated with carbon content when combined with carbon: nitrogen ratio (r2 = 0.51), black carbon content (r2 = 0.75), and Δ14C (r2 = 0.81). Total pore space was greater in PF (61 ± 3%) than in HF (55 ± 2%), but x‐ray computed tomography revealed that pore space inside soil aggregates of 4–5 mm diameter does not vary between the studied Ferralsols. We further observed nearly twice as many roots and burrows in PF compared with HF. We thus infer that the mechanism responsible for the increase in porosity is most likely an enhancement of resource availability (e.g., energy, carbon, and nutrients) for the organisms (earthworms, ants, termites, etc.) that physically displace soil particles and promote soil aggregation. As a result of increased resource availability, soil organisms can create especially the mesoscale structural soil features necessary for unrestricted water flow and rapid gas exchange. This insight paves the way for the development of land management technologies to optimize the physical shape and capacity of the soil bioreactor.

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