Plant exudates may stabilize or weaken soil depending on species, origin and time

Naveed, Muhammad ORCID:, Brown, L. K., Raffan, A. C., George, T. S., Bengough, A. G., Roose, T., Sinclair, I., Koebernick, N., Cooper, L., Hackett, C. A. and Hallett, P. D. (2017) Plant exudates may stabilize or weaken soil depending on species, origin and time. European Journal of Soil Science, 68 (6). pp. 806-816. ISSN 1351-0754

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We hypothesized that plant exudates could either gel or disperse soil depending on their chemical characteristics. Barley (Hordeum vulgare L. cv. Optic) and maize (Zea mays L. cv. Freya) root exudates were collected using an aerated hydroponic method and compared with chia (Salvia hispanica L.) seed exudate, a commonly used root exudate analogue. Sandy loam soil was passed through a 500-μm mesh and treated with each exudate at a concentration of 4.6 mg exudate g−1 dry soil. Two sets of soil samples were prepared. One set of treated soil samples was maintained at 4∘C to suppress microbial processes. To characterize the effect of decomposition, the second set of samples was incubated at 16∘C for 2weeks at −30 kPa matric potential. Gas chromatography–mass spectrometry (GC–MS) analysis of the exudates showed that barley had the largest organic acid content and chia the largest content of sugars (polysaccharide-derived or free), and maize was in between barley and chia. Yield stress of amended soil samples was measured by an oscillatory strain sweep test with a cone plate rheometer. When microbial decomposition was suppressed at 4∘C, yield stress increased 20-fold for chia seed exudate and twofold for maize root exudate compared with the control, whereas for barley root exudate decreased to half. The yield stress after 2weeks of incubation compared with soil with suppressed microbial decomposition increased by 85% for barley root exudate, but for chia and maize it decreased by 87 and 54%, respectively. Barley root exudation might therefore disperse soil and this could facilitate nutrient release. The maize root and chia seed exudates gelled soil, which could create a more stable soil structure around roots or seeds.

Item Type: Article
Identifier: 10.1111/ejss.12487
Subjects: Construction and engineering > Civil and environmental engineering
Construction and engineering
Depositing User: Muhammad Naveed
Date Deposited: 15 May 2018 13:22
Last Modified: 06 Feb 2024 15:57


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