Direct evidence using a controlled greenhouse study for threshold effects of soil organic matter on crop growth

AbstractSoil organic matter (SOM) and the carbon and nutrients therein drive fundamental submicron- to global-scale biogeochemical processes and influence carbon-climate feedbacks. Consensus is emerging that microbial materials are an important constituent of stable SOM, and new conceptual and quantitative SOM models are rapidly incorporating this view. However, direct evidence demonstrating that microbial residues account for the chemistry, stability and abundance of SOM is still lacking. Further, emerging models emphasize the stabilization of microbial-derived SOM by abiotic mechanisms, while the effects of microbial physiology on microbial residue production remain unclear. Here we provide the first direct evidence that soil microbes produce chemically diverse, stable SOM. We show that SOM accumulation is driven by distinct microbial communities more so than clay mineralogy, where microbial-derived SOM accumulation is greatest in soils with higher fungal abundances and more efficient microbial biomass production.

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Author Correction: Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls

Nature Communications ◽

10.1038/s41467-018-06427-3 ◽

2018 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Cynthia M. Kallenbach ◽

Serita D. Frey ◽

A. Stuart Grandy

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Direct Evidence ◽

Soil Organic Matter Formation

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Direct evidence for the role of microbial community composition in the formation of soil organic matter composition and persistence

ISME Communications ◽

10.1038/s43705-021-00071-7 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Luiz A. Domeignoz-Horta ◽

Melissa Shinfuku ◽

Pilar Junier ◽

Simon Poirier ◽

Eric Verrecchia ◽

...

Keyword(s):

Thermal Stability ◽

Organic Matter ◽

Microbial Community ◽

Soil Organic Matter ◽

Microbial Communities ◽

Soil Carbon ◽

Community Composition ◽

Direct Evidence ◽

Microbial Community Composition ◽

Soil Matrix

AbstractThe largest terrestrial carbon sink on earth is soil carbon stocks. As the climate changes, the rate at which the Earth’s climate warms depends in part on the persistence of soil organic carbon. Microbial turnover forms the backbone of soil organic matter (SOM) formation and it has been recently proposed that SOM molecular complexity is a key driver of stability. Despite this, the links between microbial diversity, chemical complexity and biogeochemical nature of SOM remain missing. Here we tested the hypotheses that distinct microbial communities shape the composition of SOM, and microbial-derived SOM has distinct decomposition potential depending on its community of origin. We inoculated microbial communities of varying diversities into a model soil matrix amended with simple carbon (cellobiose) and measured the thermal stability of the resultant SOM. Using a Rock-Eval® ramped thermal analysis, we found that microbial community composition drives the chemical fingerprint of soil carbon. While diversity was not a driver of SOM composition, bacteria-only communities lead to more thermally labile soil C pools than communities with bacteria and fungi. Our results provide direct evidence for a link between microbial community structure, SOM composition, and thermal stability. This evidence demonstrates the relevance of soil microorganisms in building persistent SOM stocks.

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Evaluation of POST-Directed Applications of Flumioxazin in New Mexico Chile Pepper

Weed Technology ◽

10.1017/wet.2018.83 ◽

2018 ◽

Vol 33 (1) ◽

pp. 135-141

Author(s):

Brian J. Schutte ◽

Erik A. Lehnhoff ◽

Leslie L. Beck

Keyword(s):

Organic Matter ◽

New Mexico ◽

Soil Organic Matter ◽

Field Study ◽

Organic Matter Content ◽

Matter Content ◽

Fruit Yield ◽

Chile Pepper ◽

Greenhouse Study ◽

Herbicide Control

AbstractThe objective for this study was to determine if POST-directed applications of flumioxazin reduce fruit yield for chile pepper produced on coarse- and fine-textured soils irrigated by furrow. This objective was addressed with a multiyear (2015, 2016, 2017) field study that compared flumioxazin effects on fruit yield against a commercial standard (POST-directed carfentrazone) and the absence of a POST-directed herbicide. The field study occurred at two university research farms that differed in soil texture. On fine-textured soil, treatments included the no POST–directed herbicide control and the following four POST-directed herbicides applied to raised beds: (1) flumioxazin at 107 g ai ha–1applied 4 wk after crop thinning, (2) carfentrazone at 35 g ai ha–1applied 4 wk after crop thinning, (3) flumioxazin at 70 g ai ha–1applied 4 and 6 wk after crop thinning, (4) carfentrazone at 35 g ai ha–1applied 4 and 6 wk after crop thinning. On coarse-textured soil, treatments included the no POST–directed herbicide control and the following three POST-directed herbicides applied 4 wk after crop thinning: (1) flumioxazin at 107 g ai ha–1applied to raised beds, (2) flumioxazin at 107 g ai ha–1applied to furrows, (3) carfentrazone at 35 g ai ha–1applied to raised beds. On fine-textured soil, treatment did not affect fruit yield. On coarse-textured soil, flumioxazin applied to furrows did not reduce fruit yield, but flumioxazin on raised beds reduced fruit yield of some cultivars in 2015 and 2017. Year-to-year variability in both flumioxazin-induced yield loss and soil characteristics suggested that chile pepper sensitivity to flumioxazin was negatively associated with soil organic matter content. In a follow-up greenhouse study, soil organic matter lessened flumioxazin-induced crop injury. In general, this study indicates that recommendations for POST-directed flumioxazin in New Mexico chile pepper will need to be soil-type specific.

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