Review status: this preprint is currently under review for the journal SOIL.
Assessing soil erosion of forest and cropland sites in wet tropical
Africa using 239+240Pu fallout radionuclides
Florian Wilken1,2,Peter Fiener2,Michael Ketterer3,Katrin Meusburger4,Daniel Iragi Muhindo5,Kristof van Oost6,and Sebastian Doetterl1Florian Wilken et al.Florian Wilken1,2,Peter Fiener2,Michael Ketterer3,Katrin Meusburger4,Daniel Iragi Muhindo5,Kristof van Oost6,and Sebastian Doetterl1
Received: 15 Dec 2020 – Accepted for review: 18 Dec 2020 – Discussion started: 28 Dec 2020
Abstract. Due to the rapidly growing population in tropical Africa, a substantial rise in food demand is predicted in upcoming decades, which will result in higher pressure on soil resources. However, there is limited knowledge on soil redistribution dynamics following land conversion to arable land in tropical Africa that is partly caused by challenging local conditions for long-term landscape scale monitoring. In this study, fallout radionuclides 239+240Pu are used to assess soil redistribution along topographic gradients at two cropland sites and at three nearby pristine forest sites located in the DR Congo, Uganda and Rwanda. In the study area, a relatively high 239+240Pu baseline inventory is found (mean forest inventory 41 Bq m−2). Pristine forests show no indication for soil redistribution based on 239+240Pu along topographical gradients. In contrast, soil erosion and sedimentation on cropland reached up to 37 and 40 cm within the last 55 years, respectively. Cropland sites show high intra-slope variability with locations showing severe soil erosion located in direct proximity to sedimentation sites. This study shows the applicability of a valuable method to assess tropical soil redistribution and provides insight on soil degradation rates and patterns in one of the most vulnerable regions of the World.
This study demonstrates the usability of fallout radionuclides 239Pu and 240Pu as a tool to assess soil degradation processes in Tropical Africa, which is particularly valuable in regions with limited infrastructure and challenging monitoring conditions for landscape scale soil degradation monitoring. The study shows no indication of soil redistribution in forest sites but substantial soil redistribution in cropland (sedimentation > 40 cm in 55 years) with high variability.
This study demonstrates the usability of fallout radionuclides 239Pu and 240Pu as a tool to...