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Calcium promotes persistent soil organic matter by altering microbial transformation of plant litter.

ABSTRACT: Calcium (Ca) can contribute to soil organic carbon (SOC) persistence by mediating physico-chemical interactions between organic compounds and minerals. Yet, Ca is also crucial for microbial adhesion, potentially affecting colonization of plant and mineral surfaces. The importance of Ca as a mediator of microbe-mineral-organic matter interactions and resulting SOC transformation has been largely overlooked. We incubated ⁴⁴Ca labeled soils with ¹³C¹⁵N labeled leaf litter to study how Ca affects microbial transformation of litter and formation of mineral associated organic matter. Here we show that Ca additions promote hyphae-forming bacteria, which often specialize in colonizing surfaces, and increase incorporation of litter into microbial biomass and carbon use efficiency by approximately 45% each. Ca additions reduce cumulative CO₂ production by 4%, while promoting associations between minerals and microbial byproducts of plant litter. These findings expand the role of Ca in SOC persistence from solely a driver of physico-chemical reactions to a mediator of coupled abiotic-biotic cycling of SOC.

SUBMITTER: Shabtai IA

PROVIDER: S-EPMC10587086 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Calcium promotes persistent soil organic matter by altering microbial transformation of plant litter.

Shabtai Itamar A IA Wilhelm Roland C RC Schweizer Steffen A SA Höschen Carmen C Buckley Daniel H DH Lehmann Johannes J

Nature communications 20231019 1

Calcium (Ca) can contribute to soil organic carbon (SOC) persistence by mediating physico-chemical interactions between organic compounds and minerals. Yet, Ca is also crucial for microbial adhesion, potentially affecting colonization of plant and mineral surfaces. The importance of Ca as a mediator of microbe-mineral-organic matter interactions and resulting SOC transformation has been largely overlooked. We incubated 44Ca labeled soils with 13C15N labeled leaf ...[more]

PMID: 37857604

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Project description:Organic matter input regulates the rate and temperature sensitivity (expressed as Q 10) of soil organic matter (SOM) decomposition by changing microbial composition and activities. It remains unclear how the incorporation of litter-made biochar instead of litter affects the Q 10 of SOM decomposition. Using a unique combination of two-and three-source partitioning methods (isotopic discrimination between C3/C4 pathways and 14C labeling), we investigated: (1) how maize litter versus litter-made biochar (of C4 origin) addition influenced the Q 10 of SOM (C3 origin) under 10°C warming, and (2) how the litter or biochar amendments affected the Q 10 of 14C-labeled fresh organic matter (FOM) after long-term incubation. Compared with biochar addition, litter increased the rates and Q 10 of mass-specific respiration, SOM and FOM decomposition, as well as the contents of SOM-derived dissolved organic C (DOC) and total phospholipid fatty acids (PLFA). Litter-amended soils have much higher activities (V max) of β-glucosidase, N-acetyl-β-glucosaminidase, and leucine aminopeptidase, suggesting larger enzyme pools than in soils with biochar. The Q 10 of enzyme V max (1.6-2.0) and K m (1.2-1.4) were similar between litter-and biochar-amended soils, and remained stable with warming. However, warming reduced microbial biomass (PLFA) and enzyme activity (V max), suggesting decreased enzyme production associated with smaller microbial biomass or faster enzyme turnover at higher temperatures. Reductions in PLFA content and enzyme V max due to warming were larger in litter-amended soils (by 31%) than in the control and biochar-amended soils (by 4-11%), implying the active litter-feeding microorganisms have a smaller degree of heat tolerance than the inactive microorganisms under biochar amendments. The reduction in enzyme activity (V max) by warming was lower in soils with biochar than in the control soil. Our modeling suggested that the higher Q 10 in litter-amended soils was mainly caused by faster C loss under warming, linked to reductions in microbial biomass and growth efficiency, rather than the slightly increased SOM-originated substrate availability (DOC). Overall, using straw-made biochar instead of straw per se as a soil amendment lowers the Q 10 of SOM and FOM by making microbial communities and enzyme pools more temperature-tolerant, and consequently reduces SOM losses under warming.

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Dataset Information

Calcium promotes persistent soil organic matter by altering microbial transformation of plant litter.

Publications

Calcium promotes persistent soil organic matter by altering microbial transformation of plant litter.

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