Dataset Information

Disentangling the root- and detritus-based food chain in the micro-food web of an arable soil by plant removal.

ABSTRACT: Soil food web structure and function is primarily determined by the major basal resources, which are living plant tissue, root exudates and dead organic matter. A field experiment was performed to disentangle the interlinkage of the root-and detritus-based soil food chains. An arable site was cropped either with maize, amended with maize shoot litter or remained bare soil, representing food webs depending on roots, aboveground litter and soil organic matter as predominant resource, respectively. The soil micro-food web, i.e. microorganisms and nematodes, was investigated in two successive years along a depth transect. The community composition of nematodes was used as model to determine the changes in the rhizosphere, detritusphere and bulk soil food web. In the first growing season the impact of treatments on the soil micro-food web was minor. In the second year plant-feeding nematodes increased under maize, whereas after harvest the Channel Index assigned promotion of the detritivore food chain, reflecting decomposition of root residues. The amendment with litter did not foster microorganisms, instead biomass of Gram-positive and Gram-negative bacteria as well as that of fungi declined in the rooted zone. Likely higher grazing pressure by nematodes reduced microbial standing crop as bacterial and fungal feeders increased. However, populations at higher trophic levels were not promoted, indicating limited flux of litter resources along the food chain. After two years of bare soil microbial biomass and nematode density remained stable, pointing to soil organic matter-based resources that allow bridging periods with deprivation. Nematode communities were dominated by opportunistic taxa that are competitive at moderate resource supply. In sum, removal of plants from the system had less severe effects than expected, suggesting considerable food web resilience to the disruption of both the root and detrital carbon channel, pointing to a legacy of organic matter resources in arable soils.

SUBMITTER: Glavatska O

PROVIDER: S-EPMC5509179 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Disentangling the root- and detritus-based food chain in the micro-food web of an arable soil by plant removal.

Glavatska Olena O Müller Karolin K Butenschoen Olaf O Schmalwasser Andreas A Kandeler Ellen E Scheu Stefan S Totsche Kai Uwe KU Ruess Liliane L

PloS one 20170713 7

Soil food web structure and function is primarily determined by the major basal resources, which are living plant tissue, root exudates and dead organic matter. A field experiment was performed to disentangle the interlinkage of the root-and detritus-based soil food chains. An arable site was cropped either with maize, amended with maize shoot litter or remained bare soil, representing food webs depending on roots, aboveground litter and soil organic matter as predominant resource, respectively. ...[more]

PMID: 28704438

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Project description:The sequestration in soil of organic carbon (SOC) derived from atmospheric carbon dioxide (CO2) by replacing arable crops with leys, has been measured over 70?years on a sandy loam soil. The experiment was designed initially to test the effect of leys on the yields of arable crops. A 3-year grazed grass with clover (grass?+?clover) ley in a 5-year rotation with arable crops increased percentage organic carbon (%OC) in the top 25?cm of the soil from 0.98 to 1.23 in 28?years, but with little further increase during the next 40?years with all-grass leys given fertilizer nitrogen (N). In this second period, OC inputs were balanced by losses, suggesting that about 1.3% OC might be near the equilibrium content for this rotation. Including 3-year lucerne (Medicago sativa) leys had little effect on %OC over 28?years, but after changing to grass?+?clover leys, %OC increased to 1.24 during the next 40?years. Eight-year leys (all grass with N or grass?+?clover) in 10-year rotations with arable crops were started in the 1970s, and after three rotations %OC had increased to ca. 1.40 in 2000-2009. Over 70?years, %OC declined from 0.98 to 0.94 in an all-arable rotation with mainly cereals and to 0.82 with more root crops. Applications of 38?t?ha-1 farmyard manure (FYM) every fifth year increased %OC by 0.13% by the mid-1960s when applications ceased. Soil treated with FYM still contained 0.10% more OC in 2000-2009. Changes in the amount of OC have been modelled with RothC-26.3 and estimated inputs of C for selected rotations. Little of the OC input during the 70?years has been retained; most was retained in the grazed ley rotation, but 9?t?ha-1 only of a total input of 189?t?ha-1. In other rotations more than 98% of the total OC input was lost. Despite large losses of C, annual increases in OC of 4‰ are possible on this soil type with the inclusion of grass or grass?+?clover leys or the application of FYM, but only for a limited period. Such increases in SOC might help to limit increases in atmospheric CO2.HighlightsCan leys sequester significant amounts of atmospheric CO 2 in SOM and contribute to the 4‰ initiative?Changes in the percentage and amount of OC were measured and modelled over 70?years and OC losses estimated.Three-year grass or grass?+?clover leys increased %OC, but only to an equilibrium level that was then maintained.Despite large losses, sequestering CO 2-C at 4‰?year-1 by growing grass or grass?+?clover leys is possible.

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Dataset Information

Disentangling the root- and detritus-based food chain in the micro-food web of an arable soil by plant removal.

Publications

Disentangling the root- and detritus-based food chain in the micro-food web of an arable soil by plant removal.

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