Fundamental bases of biological soil resilience

Soils underpin our civilisation, since we rely on them to provide a wide range of goods and services such as food production, water storage and purification, nutrient cycling, support for biodiversity and a platform on which we reside. However, they are constantly subjected to stresses and pressures which may compromise their ability to deliver these functions. Such pressures are increasing as a result of the accelerating demands placed on soils, compounded by climate change. Healthy soils can be defined as those that are able to deliver the range of desired functions, withstand such pressures applied to them, and recover from such challenges - in other words, soils need to be resilient. We know little of what actually makes soils more or less resilient, and what the mechanisms are which govern such behaviour. We think it may be related to a combination of their inherent properties (i.e. what they comprise), and external factors (such as their position in the landscape and the way they have been managed). We propose to identify which are the key properties of soils that relate to their resilience. Our approach will be to consider a particular soil function related to the biological activity of soils, which is indicative of many of the more general functions that soils carry out. We propose to take soil samples from a wide spread across England so that we have a big range in basic properties and circumstances, and determine their resilience in the laboratory using a technique which measures biological activity following perturbation arising from drying and wetting cycles. Knowing both the soil properties and the associated resilience, we can then explore the relationships between the two. We think that it is unlikely that resilience is due to one particular soil characteristic, but a combination of factors. In order to elucidate such relationships we will develop and apply a combination of mathematical and statistical approaches which are suited to such tasks. The results will let us then establish both what it is that underpins soil resilience, and also the extent to which we may be able to impart resilience onto soils, for example by how we manage them. We will also use the data to produce a prototype map of soil resilience for England, which will be informative in terms of identifying which soils are more or less robust and therefore may need particular approaches to ensure the maintenance of their health. This proposal addresses the Living with Environmental Change initiative by developing understanding of the ways in which soils may be managed to resist environmental change.

Soils are subjected to a range of environmental perturbations, and need to be able to adapt to these in order to deliver functions which underpin delivery of ecological goods and services. A better understanding of the basis of such resilience will lead to an ability to improve soil management to enhance delivery of such functions and withstand stresses. Knowledge of factors which underpin soil resilience is limited, not least because there are few coherent data which can be used to robustly explore quantitative relationships between putative governors and resilience phenomena. Preliminary work using published data suggests that soil type, parent material and soil texture appear to be dominant in determining soil resilience in general, and aspects of the soil microbial community are also pertinent. It was notable that organic matter content and land-use, which are commonly hypothesised (and occasionally demonstrated) to be influential, ranked amongst the least significant factors. We hypothesise that a combination of intrinsic and extrinsic factors underpin biological soil resilience, and propose to determine the nature of such relationships by a thorough quantification of an indicative biologically-mediated soil function and a model perturbation (respiratory responses in relation to repeat drying and rewetting). Genotypic and phenotypic resilience functions will also be considered. This will provide a range of both intrinsic and extrinsic properties, and data of appropriate resolution to robustly parameterise resilience (using an innovative model based upon damped-oscillator concepts), and formally model relationships using Bayesian belief networks. The results will be used to establish the extent to which resilience might be imparted onto soils, and where feasible, management guidelines to realise such properties. The data will also be used to generate a prototype indicative map of soil resilience for England, as a case study for application of such knowledge.

The production of an indicative map of soil resilience for England based upon the comprehensive data and sophisticated modelling approaches developed in the study, will be of great utility to policy makers. This is both from the perspective of the demonstration of the realisation of such a map, but also practically to UK policy practitioners who require to be informed of the state of the nation's soils in order to set and manage environmental monitoring and protection strategies. We will ensure that such results are fed into policy fora by direct dialogue with appropriate agencies and practitioners, including Defra, the Environment Agency and Natural England. To achieve this we will invite members of the above organisations to a workshop publicising our findings . By establishing the bases of soil resilience we will be in an informed position to establish the extent to which elevated resilience might be imbued into soils - and just as importantly, where this is not practicable. Such information is of crucial importance to land managers. We will produce briefing material accordingly, which will be made available to land managers via online-accessible material, and promulgated through a range of professional trade associations and societies (publication in trade journals) and to a wider audience through the production of briefing notes and press releases.