Plant-based controls on soil structural dynamics: elucidating the interactive roles of the genotype, phenotype and soil microbial community

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Healthy soils have good structure - a diverse and well-connected pore network. This arises from aggregation of soil constituents dependent on biological activity; plant roots modify soil mechanically and promote microbial activity and these effects interact. We will examine a range of 94 wheat lines, known to have extreme variation in root phenotypic architecture, which constitute a quantitative trait loci mapping population. We will measure the effects of all these lines on soil structural genesis and dynamics, and will treat both the soil physical structure and microbial phenotype as part of an 'extended trait space' along with the root architectural phenotype. We will screen the lines in microcosms with experimentally-destructured soils to allow high-throughput. This will show where there are major genetic loci regulating the extended trait space of soil and microbial communities manifest by the wheat lines, and associated soil structural genesis. A subset of lines with a range of responses will then be grown in experimental soil columns at larger scales, and for the plant life cycle, to characterize their effects in more detail, and to elucidate factors that affect soil structural conditioning, e.g. root biomass, root architecture, extra-cellular polysaccharide, and operationally active components of the microflora, particularly fungi. Root and soil architecture will be determined in situ and in 3D by X-ray computed tomography. Soil structural measures at core scale will be related to the overall root architecture and microbial properties. Novel methods for multiscale analysis will also be used to examine the pore to core scales. These will make use of wavelet transforms and non-stationary linear mixed models to characterize the modification of soil structure in the vicinity of roots. We will then examine whether there are synergies with respect to effects on soil structure when lines with contrasting but complementary properties are grown in combination.

The principal impacts we wish to attain with this project are:

(i) a practitioner-level awareness of the concepts and findings arising from this research, particularly in relation to the potential that maincrops could contribute to soil health through enhanced structure;

(ii) a wider understanding of the concepts and potential of such approaches by policy communities;

(iii) utilisation of the data and knowledge acquired by the environmental sciences academic community.

These will be achieved by the establishment of a project related website and periodic production of briefings which will be posted on the site and distributed via a group of 'Promulgation Partners' who have agreed to use their respective communications networks to disseminate the instigation of the project and the key findings as they are realised. This will include material on their websites and online portals, newsletters and annual member meetings and trade conferences.

Project members will also give series of talks and seminars to growers and various fora which the investigators are regularly contribute to, which will include two attendances to the key UK cereal-producer event, Cereals.