Understanding the role of water and tillage erosion from ^239+240Pu tracer measurements using inverse modelling

Soil redistribution on arable land is a major threat for a sustainable use of soil resources. The majority of soil redistribution studies focus on water erosion, while wind and tillage erosion also induce pronounced redistribution of soil materials. Tillage erosion especially is understudied, as it does not lead to visible off-site damages. The analysis of on-site/in-field soil redistribution is mostly based on tracer studies, where radionuclide tracers (e.g. 137Cs, 239+240Pu) from nuclear weapon tests are commonly used to derive the erosion history over the past 50–60 years. Tracer studies allow us to determine soil redistribution patterns but integrate all types of soil redistribution processes and hence do not allow us to unravel the contribution of individual erosion processes. The aim of this study is to understand the contribution of water and tillage erosion leading to soil patterns found in a small hummocky ground moraine kettle hole catchment under intensive agricultural use. Therefore, 239+240Pu-derived soil redistribution patterns were analysed using an inverse modelling approach accounting for water and tillage erosion processes. The results of this analysis clearly point out that tillage erosion is the dominant process of soil redistribution in the study catchment, which also affects the hydrological and sedimentological connectivity between arable land and the kettle hole. A topographic change up to 17 cm (53 yr)−1 in the eroded parts of the catchment is not able to explain the current soil profile truncation that exceeds the 239+240Pu-derived topographic change substantially. Hence, tillage erosion already started before the onset of intense mechanisation since the 1960s. In general, the study stresses the urgent need to consider tillage erosion as a major soil degradation process that can be the dominant soil redistribution process in sloped arable landscapes.

Understanding the role of water and tillage erosion from ^239+240Pu tracer measurements using inverse modelling

Soil redistribution on arable land is a major threat for a sustainable use of soil resources. The soil redistribution process most studies focus on is water erosion, while wind and tillage erosion also induce pronounced redistribution of soil materials. Especially, tillage erosion is understudied, as it does not lead to visible off-site damages. The analysis of on-site/in-field soil redistribution is mostly based on tracer studies, whereas radionuclide tracers (e.g. 137Cs, 239+240Pu) from nuclear weapon tests are commonly used to derive the erosion history over the past 50–60 yr. Tracer studies allow to determine soil redistribution patterns, but integrate all kinds of soil redistribution processes and hence do not allow to unravel the contribution of different erosion processes. The aim of this study is to understand the contribution of water and tillage erosion leading to soil patterns found in a small hummocky ground moraine catchment under intensive agricultural use. Therefore, 239+240Pu derived soil redistribution patterns were analysed using an inverse modelling approach accounting for water and tillage erosion processes. The results of this analysis clearly point out that tillage erosion is the dominant process of soil redistribution in the small catchment, which also affects the hydrological and sedimentological connectivity between arable land and the kettle hole. A topographic change up to 17 cm (53 yr)−1 in the eroded parts of the catchment is not able to explain the current soil profile truncation that exceeds the 239+240Pu derived topographic change substantially. Hence, tillage erosion is not limited to the time since the onset of intense mechanisation since the 1960s. In general, the study stresses the urgent need to consider tillage erosion as a very important soil degradation process that drives patterns of soil properties in our arable landscapes.

Complex soil mass redistribution along a catena using meteoric and in-situ 10Be as tracers

<p><span>In hilly and mountainous landscapes, the bedrock is actively converted to a continuous soil mantle. The bedrock-soil interface lowers spatially at the soil production rate, and the soil acts as a layer removing sediment produced locally and transported from upslope. Forested soils of a hummocky ground moraine landscape in Northern Germany exhibit strongly varying soil thicknesses with very shallow soils on crest positions and buried soils at the footslope. We explored the explanatory power of both <sup>10</sup>Be forms (in situ and meteoric) for forest soils on a hillslope to shed light into the </span><span>complex mass redistribution. </span><span>Our main research questions were: how do meteoric and in-situ <sup>10</sup>Be compare to each other? What do they really indicate in terms of soil processes (erosion, sedimentation, reworking)? </span><span>By using both types of <sup>10</sup>Be, the dynamics of soils and related mass transports should be better traceable</span><span>. Both <sup>10</sup>Be forms were measured along three profiles at different slope positions: Hydro1 (summit), Hydro3 (shoulder), Hydro4 (backslope). Furthermore, a buried horizon was found in the profile Hydro4 at 160 cm depth and <sup>14</sup>C-dated. The distribution pattern of meteoric <sup>10</sup>Be of Hydro4 shows an inverse exponential depth profile, and an almost uniform content of in-situ <sup>10</sup>Be along the profile. Meteoric <sup>10</sup>Be indicates on the one hand that a new soil was put on top of an older, now buried soil. On the other hand, meteoric <sup>10</sup>Be is involved in pedogenetic processes and clearly exhibits clay eluviation in the topsoil and clay illuviation in the subsoil. The uniform content of the in situ <sup>10</sup>Be shows soil mixing that must have occurred during erosion and sedimentation. The<sup>14</sup>C dated buried soil horizon indicates a deposition of eroded soil material about 7 ka BP. Consequently, an increase in the in-situ <sup>10</sup>Be content towards the surface should be expect which however was not the case. The reason for this is so far unknown. Radiocarbon dating and <sup>10</sup>Be data demonstrate that strong events of soil mass redistribution in Melzower Forest are mainly a result of ancient natural events. Further measurements of fallout radionuclides (<sup>239+240</sup>Pu) showed no erosion for the last few decades in the same catchment.</span></p>

Mapping Glacier Forelands Based on UAV BVLOS Operation in Antarctica

The aim of this article is to show geomorphological mapping of remote Antarctic locations using images taken by a fixed-wing unmanned aerial vehicle (UAV) during the Beyond Visual Line of Sight (BVLOS) operations. We mapped landform assemblages developed in forelands of Ecology Glacier (EGF), Sphinx Glacier (SGF) and Baranowski Glacier (BGF) in Antarctic Specially Protected Area No. 128 (ASPA 128) on King George Island (South Shetland Islands) and inferred about glacial dynamics. The orthophoto and digital elevation model allowed for geomorphological mapping of glacial forelands, including (i) glacial depositional landforms, (ii) fluvial and fluvioglacial landforms, (iii) littoral and lacustrine landforms, (iv) bodies of water, and (v) other. The largest area is occupied by ground moraine and glacial lagoons on EGF and BGF. The most profound features of EGF are the large latero-frontal moraine ridges from Little Ice Age and the first half of the 20th century. Large areas of ground moraine, frequently fluted and marked with large recessional moraine ridges, dominate on SGF. A significant percentage of bedrock outcrops and end moraine complexes characterize BGF. The landform assemblages are typical for discontinuous fast ice flow of tidewater glaciers over a deformable bed. It is inferred that ice flow velocity decreased as a result of recession from the sea coast, resulting in a significant decrease in the length of ice cliffs and decrease in calving rate. Image acquisition during the fixed-wing UAV BVLOS operation proved to be a very robust technique in harsh polar conditions of King George Island.

Textural diversity in selected Retisols in the catena of the Opalenica Plain (western Poland)

The investigation was carried out in the catena of Retisols within the Opalenica Plain. The aim of the study was to characterize the variation in texture of selected Retisols formed from ground moraine glacial till of Leszno Phase of Vistulian glaciation. The analyzed soils are characterized by a similar degree of soil material segregation, which is characteristic for the typical glacial till. Particle size distribution and granulometric indices lead to conclusion that soils located in the catena on summit and shoulder positions, have vertical texture distribution formed primarily by lessivage process. Sandy texture of eluvial horizons noted in the Retisol of the slope pediment can be a consequence of not only lessivage but also of slope forming processes that led to the appearance of lithic discontinuity. The cluster analysis using Ward’s method and 1-rPearson as the distance measure can be helpful for identification the lithogenic uniformity and/or non-uniformity of soil parent material.