Resistance to perturbation in agricultural land: Can we identify and fingerprint functional soil conditions across scales?

Managing the land sustainably is important to nature and human wellbeing. The way that agricultural land is managed, and the plant species which are grown on it, can influence biological, physical and chemical characteristics of soil, and affect its ability to recycle nutrients, grow crops, feed grazing animals, regulate water movement and store carbon. The effects of higher management intensity over an extended period of time (e.g. continuous cropping, increased use of fertilisers, higher grazer densities) is likely to degrade soil quality and reduce its ability to sustain the various services that it provides such as food production, water and nutrient cycling. Understanding how different agricultural land management practices may impact soil conditions is therefore important so that soil quality can be maintained or improved. Poor quality soils may also be more susceptible to perturbations such as flooding and drought. Since these climatic events are becoming more frequent in the UK, it is also vital that we recognise management practices and soil conditions that confer resistance to such perturbations.
This project aims to identify the influence of plant composition, land management and soil type on soil characteristics considered as indicators of soil quality. It will use existing data from a UK-wide monitoring programme and create new data using archive soil samples to examine soil indicators (e.g. organic matter concentration) and biophysical resistance (e.g. soil aggregate stability) across the gradient from arable to semi-natural grassland management. This work will also evaluate whether combinations of soil quality indicators differ between climatic regions and soil types of the UK.

Since the measurement of soil properties with extensive sampling can often require detailed, time-consuming and expensive laboratory analyses, there has been a drive towards the development and use of proximal approaches for measuring soil properties. These approaches include the use of spectral measurements, which examine the reflectance of different wavelengths of light from soil samples, and are used to derive calibrations which can be validated and use to estimate soil properties using the spectral information. Model calibrations will be derived for three different spectral methods and digital imagery, including spatial environmental data, and the utility and predictive ability of these approaches to fingerprint soil quality indicators compared. The methods using visible spectra and digital imagery will then be applied and field-tested, across landscape gradients and in field experiments, and appraised with regard to the cost and utility for estimating soil quality indicators across scales.

This project will quantify how soil quality indicators are affected by environmental factors and how it changes across a gradient of agricultural land management, and identify conditions that determine the ability of different soils to resist and recover from perturbations. It will also test the ability of spectral measurements to fingerprint soil quality and resistance with the potential to provide a rapid evaluation of soil quality under different management practices. Overall, it will generate new scientific insight to inform the sustainable management of UK soils and provide practical tools to estimate soil functioning on agricultural land.

Agricultural land management controls the delivery of functions and services provided by soils. Changes in management intensity can degrade soil quality and its multifunctional capacity. It is therefore of critical importance to broaden understanding of how different agricultural land management practices may impact soil conditions and also how changes may alter the ability of the soil to resist perturbations such as flooding and drought. The research and policy community will benefit from the scientific insight generated by the project, including improved understanding of the links between above and belowground systems under agricultural land management, and extended knowledge of the key controls on soil quality indicators. It will also leave a legacy of large-scale datasets on key soil indicators and spectral data using visible (VIS), near-infrared (NIR) and mid-infrared (MIR) approaches, linked to existing co-located environmental data, across a broad gradient of agricultural land use from arable to semi-natural grassland. These data have excellent potential for re-use and contribution to further large-scale modelling and mapping is expected. The findings from the project will impact farmers and land managers by providing spatially relevant information to help with land management decisions for sustainable soil functions under changing climate. The tools developed in the project also have the potential to provide the ability for cheaper, more rapid evaluation of soil quality under different management practices, and the ability to measure these more intensively over time. The development of a smartphone app mean that such tools could be readily adopted. Together, the findings of the project inform the sustainable management of UK soils and provide the practical tools to estimate soil functioning on agricultural land.