A major challenge facing grassland farmers is the need to maintain, or bolster, essential soil functions that underpin forage production and quality. Of particular importance for this is the soil microbial community, or microbiome, which interacts closely with roots and has beneficial and negative consequences for plant growth. While scientists are becoming increasingly aware of the importance of these two-way interactions between roots and the soil microbiome for plant growth, we remain largely in the dark about the mechanisms involved, especially regarding how roots shape the soil microbiome and its functioning in soil. This not only represents a major knowledge gap, but also it hinders the ability of farmers to capitalise on these interactions, for instance by manipulating soil microbial communities to deliver desired soil functions in a sustainable way. This studentship focuses on a long-standing tenet of grassland farming: grass growth is greater in grazed than ungrazed swards, namely compensatory growth. This has traditionally been put down to the return of dung and urine, which boosts soil nutrient cycling and supply of nutrients to plants. But new evidence points to another mechanism, namely the stimulation of beneficial microbes in the root zone of defoliated plants, which increases plant nutrient supply and plant regrowth. This studentship will tackle this and test how defoliation of a broad range of grass species modifies the diversity and function of the soil microbiome, and explore how this affects the uptake of nutrients by defoliated plants, and their competitive interactions in mixed grassland swards. This will be tested in a series of laboratory and field-based studies using state-of-the-art molecular tools for interrogating the soil microbiome and stable isotope techniques that allow us to trace the flow of carbon and nutrients through the plant-soil-microbial system. This will yield new insights into the importance of associations between roots of grassland plants and the soil microbiome in controlling plant responses to defoliation, and deliver new insights into the complexities of the soil microbiome and its link to soil functioning, which is key to sustainable grassland management.
Applications are invited from UK/EU nationals only. Applicants must have obtained, or be about to obtain, at least an upper second class honours degree (or equivalent) in a relevant subject.
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