Climate impacts on soil susceptibility to erosion.

Soil erosion threatens soil sustainability and the provision of ecosystem services and is predicted to increase in the future with climate change. Soil erodibility, the susceptibility of soil to erosion, is often estimated as a constant variable but the best indicator of erodibility is aggregate stability, which is a dynamic soil property and has been observed to vary with changes in local climatic conditions. Aggregate stability is influenced by biological stabilisation and the soil microbial community are known to respond to changes in climatic conditions, yet whether aggregate dynamics can be explained by shifts in the soil microbial community has not been fully investigated. This thesis aims to investigate the influence of climatic conditions, in terms of soil temperature and moisture content, on aggregate stability, and thus soil erodibility, and whether these dynamics are explained by climate-induced changes in the soil microbial community. Environmental chambers and a rainfall simulator were used to examine the effects of climatic conditions and rainfall on aggregate stability and soil microbial properties as indicators of biological stabilisation in single-layer and multi-layered aggregate microcosms. The key findings show that temperature and moisture content significantly affected aggregate stability and the influence of soil temperature and moisture on soil microbial properties is soil texture dependent. Soil microbial properties were significant predictors of aggregate stability. Aggregate stability did not differ between climate scenarios in seasonal treatments but was significantly lower in seasonal treatments compared to constant seasons. Soil temperature and moisture significantly affected soil erodibility related to changes in aggregate stability and the soil microbial community. Rainfall significantly affected microbial properties in eroded soil and selectively mobilised a fungal-dominated component of the microbial community, influenced by preceding climatic treatments. The research highlights the further need to (i) recognise the role of climate-driven microbial shifts mediating aggregate stability mechanistically; and (ii) integrate knowledge on aggregate- scale mechanisms across larger spatial scales.PhD in Water, including Desig

Do temperature and moisture conditions impact soil microbiology and aggregate stability?

Purpose: Studies predicting the impacts of climate change on erosion have considered numerous variables, such as rainfall erosivity and vegetation cover, but have not considered potential changes in soil erodibility. Erodibility is an intrinsic property of the soil, strongly correlated with the stability of soil aggregates. It is influenced by soil physico-chemical attributes, including the microbiological community. The study aim was to determine how shifts in temperature and moisture conditions, which other studies have shown affect microbiological communities, might affect aggregate stability. Methods: Using an experimental approach with laboratory microcosms, aggregates from a sandy loam soil and a clay soil were incubated at three temperatures and three moisture conditions in a factorial experimental design. Aggregate stability was quantified using rainfall simulation. Microbiological indicator metrics were measured to evaluate treatment microbiological impacts, including community composition (PLFA), biomass carbon, and respiration. Results: Temperature and moisture content affected aggregate stability significantly, but differently for the two soil types tested. For the sandy loam soil, aggregate stability decreased significantly with increasing moisture content. For the clay soil, aggregate stability increased significantly with increasing temperature. For both soil textures, temperature and moisture content affected microbiological community composition and respiration. Regression analysis indicated that microbiological properties were significant predictors of aggregate stability. Conclusion: Our results emphasise the dynamic nature of soil aggregate stability. Changes in microbiological metrics suggest possible biological mechanisms for aggregate stability changes, which should be investigated further to better understand the potential impacts of climate change on soil erodibility and erosion.Natural Environment Research Council (NERC): NE-M009106-1 BBSR

Contributions and future priorities for soil science: comparing perspectives from scientists and stakeholders

Soils are a fundamental natural resource but intensifying demands and increasing soil degradation necessitate focussed research into the sustainable use of soils. Since soil functioning is critical for the operations and performance of multiple industries, businesses and municipalities, soil scientists need to actively engage with these bodies to orientate research goals towards stakeholder needs. To achieve this, stakeholder views about the current and potential contributions of soil science to different sectors need to be taken into account when setting the future research agenda. Here, we assessed whether the current and future research priorities of soil science match the needs of four major industrial and environmental sectors: agriculture, ecosystem services and natural resources, waste management, and water management. We used an online questionnaire, distributed to 192 organisations and via social media, to compare stakeholders' and scientists' perceptions of (a) the contributions of soil science to date, (b) the areas not currently served by soil science and (c) future research needs in soil science. Stakeholders generally rated the contributions of soil science to date as ‘great’ or ‘fundamental’, but scientists rated the contributions more highly. Respondents identified numerous areas that soil research has not yet sufficiently addressed, which were mostly sector-specific and often overlapped with perceived future research needs. Importantly, stakeholders' and scientists' views of future research priorities differed strongly within sectors, with the notable exception of agriculture, where views were generally consistent. We conclude that soil science may hold unexplored potential in several industrial and environmental sectors. We call for improved research communication and greater stakeholder involvement to shape the future soils research agenda and ensure the sustainable use of soils across multiple areas of society