Arable soil formation and erosion: a hillslope-based cosmogenic nuclide study in the United Kingdom

Simon M Mudd,Timothy A Quine,Andrew M Tye,Ángel Rodés,Jessica A C Davies,Daniel L Evans,John N Quinton

doi:10.5194/soil-5-253-2019

Abstract

Abstract. Arable soils are critical resources that support multiple ecosystem services. They are frequently threatened, however, by accelerated erosion. Subsequently, policy to ensure their long-term security is an urgent societal priority. Although their long-term security relies upon a balance between the rates of soil loss and formation, there have been few investigations of the formation rates of soils supporting arable agriculture. This paper addresses this knowledge gap by presenting the first isotopically constrained soil formation rates for an arable (Nottinghamshire, UK) and coniferous woodland hillslope (Shropshire, UK). Rates ranged from 0.026 to 0.096 mm yr−1 across the two sites. These rates fall within the range of previously published rates for soils in temperate climates and on sandstone lithologies but significantly differed from those measured in the only other UK-based study. We suggest this is due to the parent material at our sites being more susceptible to weathering. Furthermore, soil formation rates were found to be greatest for aeolian-derived sandstone when compared with fluvially derived lithology raising questions about the extent to which the petrographic composition of the parent material governs rates of soil formation. On the hillslope currently supporting arable agriculture, we utilized cosmogenically derived rates of soil formation and erosion in a first-order lifespan model and found, in a worst-case scenario, that the backslope A horizon could be eroded in 138 years with bedrock exposure occurring in 212 years under the current management regime. These findings represent the first quantitative estimate of cultivated soil lifespans in the UK.

Highlights

Soil erosion is a significant threat to society (Pimentel et al, 1995; UNCCD, 2017)
Rates derived for two UK catena sequences using cosmogenic radionuclide analysis range from 0.026 to 0.096 mm yr−1, with mean rates being 0.048 ± 0.008 and 0.070 ± 0.010 mm yr−1 for Rufford Forest Farm and Comer Wood, respectively
By combining soil formation rates from Rufford Forest Farm with soil erosion rates derived from a prior isotopic study in a first-order lifespan model, we estimate that in a worst-case scenario the soil that currently comprises the A horizon on the backslope may be eroded in 138 years and bedrock exposure may occur in 212 years

Summary

Introduction

Soil erosion is a significant threat to society (Pimentel et al, 1995; UNCCD, 2017). Left unchecked, can lead to the removal of the soil cover and the exposure of the underlying parent material (Amundson et al, 2015). The development of soil conservation strategies has long been an active field for research and practice (Panagos et al, 2016; Govers et al, 2017). Given any long-term strategy to preserve soil resources relies upon a balance between the rates of soil loss and soil renewal (Hancock et al, 2015), the measurement of soil formation is a fundamental component in these conservation efforts. Efforts to quantify the rates at which soils form from

Methods

Results

Conclusion