The nature of the soil surface, for example in terms of porosity, structural resilience or hydrophobicity,
affects the extent to which water enters the soil matrix (and thus is stored and available to plants) or runs off (potentially
leading to soil erosion, pollution of waterways and increased flooding). Some commercially significant soils are prone to
aggregate breakdown at the surface under rainfall/irrigation, leading to the formation of seals and caps which can impair
crop emergence, affecting both yield and quality and significantly reduce infiltration. Whilst there has been extensive
research into the physico-chemical processes involved in this zone, there has been remarkably little consideration of the
role that micro-organisms play in affecting key processes occurring at the soil surface in arable and horticultural systems,
particularly in the UK context.
We propose to quantify the extent to which different types of soil micro-organisms affect the interactions between rainfall,
and the structural and hydrological properties of the immediate soil surface. We will achieve this by experimentally
manipulating which organisms dominate the microbial community at the soil surface, applying simulated rainfall, and
measuring soil structure, the extent to which water infiltrates the soil, how much the soil repels water, and the physical
strength of developed surfaces. We will include soils which have been managed by farmers to promote re-aggregation
and structural integrity in ways which lead to different microbial communities being present. We will also study how the
intensity and kinetic energy of rainfall affects these phenomena, which is important to understand since climate change
will affect both storm as well as the energies of individual raindrops impacting the soil surface. Climate change is
predicted to increase rainfall intensity, but currently we have no knowledge about how soil management will affect such
biological and physical interactions. The results of this research will tell us how the soil microbial community affects the
performance of the soil surface, and provide the fundamental knowledge necessary for designing ways to manage soil
systems more effectively and sustainably.
By establishing the extent to which the soil surface biota affect key hydrological and structural properties of managed
soils, we will be in an informed position to establish the extent to which such phenomena may be managed, and
potentially by what means. Just as importantly, we will be informed as to where and when this may not practicable.