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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 mmyr-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. [ABSTRACT FROM AUTHOR]

The increasing pressure humans place on the land has led to the acceleration of soil erosion, to an extent where human-induced erosion of the soil is expected to outpace the production of new soil by more than an order of magnitude. Given that the thickness of the pedosphere is a first order control on soil functions, with thicker soils having a greater capacity for water, carbon and nutrient storage, the continued thinning of non-renewable soil profiles and the associated consequences on their productivity and health is arguably one of the most significant threats to soil sustainability. Despite the fact that the future long-term security of soils depends on mitigating soil erosion rates down to (and below) the rates of soil formation, our knowledge of the latter is surprisingly meagre. Recent developments in cosmogenic radionuclide analysis have catalysed greater investment in the derivation of soil formation data, and yet there still exists no isotopically-constrained study of soil formation in arable contexts. Arable soils are often the loci for accelerated erosion but in the absence of comparative soil formation data, the magnitude of the threat this accelerated erosion places on arable soils is unknown. Future policy to ensure their long-term security, and the delivery of multiple ecosystem services, demands greater work in quantifying soil formation in these contexts. Our research is the first in the world to respond to this call and here we present the first soil formation rates under arable soils. Saprolite was extracted at the soil-bedrock interface down a catena sequence at Rufford Forest Farm (Nottinghamshire, UK) and processed through cosmogenic radionuclide analysis. Further samples from a catena sequence in a woodland near Quatt (Shropshire, UK) were also processed. We will present our isotopically constrained rates with reference to the relationship between soil formation and soil depth and in the context of the worldwide soil formation rate inventory. [ABSTRACT FROM AUTHOR]