Documenting soil redistribution on livestock‐poached pasture using caesium‐134 and cobalt‐60 as tracers

Abstract

Poaching is caused by the excessive trampling of soil and vegetation by herd animals and is prevalent in intensively managed grasslands. It is viewed as detrimental to soil fertility, has the potential to contribute to soil erosion, and thus represents a form of land degradation that is unsustainable. Attempts to document sediment redistribution by poaching have been hampered by a lack of techniques capable of measuring the movement of poached material at requisite spatial and temporal scales. We present a new tracing technique, using caesium‐134 (134Cs) and cobalt‐60 (60Co), which is designed to overcome those problems. Nine areas (plots) of grassland, each measuring 0.04 m2, were directly labelled with a known activity of either 134Cs or 60Co. Three plots were located on level, unpoached ground for use as controls, and six were located in livestock‐poached areas. Initial surface inventories were documented and then remeasured on three occasions after rainfall. Inventory changes were converted to estimates of sediment redistribution, which was documented across all poached plots at each remeasurement. Erosion represented the predominant mechanism, with average soil losses estimated at an equivalent of 0.03 kg m−2 d−1 at the first remeasurement (T1), 0.11 kg m−2 d−1 at T2, and 0.18 kg m−2 d−1 at T3. Despite assuming erosion would diminish, increasing soil loss is attributed to reduced surface roughness. These findings not only confirm the viability of the tracing technique but also demonstrate that livestock‐poached areas act as sediment sources over timescales of at least a few months after poaching has ceased.

Understanding the role of water and tillage erosion from <sup>239+240</sup>Pu tracer measurements using inverse modelling

“…The radioisotope 137 Cs has been used as a soil redistribution tracer in a large number of studies (e.g. Van Oost and Porto and Walling, 2012;Zhang, 2015;Greenwood and Meusburger, 2019;Srivastava et al, 2019) and has become a widely used method https://doi.org/10.5194/soil-2020-22 Preprint. Discussion started: 22 April 2020 c Author(s) 2020.…”

Rainfall event‐based surface runoff and erosion in small watersheds under dairy and direct‐seeding grain production

“…In North Devon, UK, excessive ground trampling by livestock herds led to an increase in soil loss rates. This was attributed to the effect of the reduction in surface roughness in the trampled areas, promoting greater connectivity and more frequent flow (Greenwood & Meusburger, 2019). In Ethiopia, the identification of sources and the extent of sedimentation in small-scale irrigation schemes, staggered with livestock activity, showed that channel sedimentation occurs through disturbances caused by cattle encroaching on the river banks to graze and drink water (Dessalegn et al, 2021).…”