scholarly journals Assessing soil redistribution of forest and cropland sites in wet tropical Africa using <sup>239+240</sup>Pufallout radionuclides

SOIL ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 399-414
Author(s):  
Florian Wilken ◽  
Peter Fiener ◽  
Michael Ketterer ◽  
Katrin Meusburger ◽  
Daniel Iragi Muhindo ◽  
...  

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 into arable land in tropical Africa that is partly caused by infrastructure limitations 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 239+240Pu baseline inventory is found that is higher than typically expected for tropical regions (mean forest inventory 41 Bq m−2). Pristine forests show no indication of soil redistribution based on 239+240Pu along topographical gradients. In contrast, soil erosion and sedimentation on cropland reached up to 37 cm (81 Mg ha−1 yr−1) and 40 cm (87 Mg ha−1 yr−1) 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 into soil degradation rates and patterns in one of the most socio-economically and ecologically vulnerable regions of the world.

2020 ◽  
Author(s):  
Florian Wilken ◽  
Peter Fiener ◽  
Michael Ketterer ◽  
Katrin Meusburger ◽  
Daniel Iragi Muhindo ◽  
...  

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.


2021 ◽  
Vol 7 (3) ◽  
pp. 33-41
Author(s):  
G. Djalilova ◽  
F. Mamatkulova ◽  
Z. Mamatkulova

Rational use of natural resources and preservation of environment in good conditions are the basis of stable state of the ecosystem. Mountain soil erosion is the most common process of degradation. Soil protection from erosion is becoming a global problem in the world, and in Uzbekistan, in particular. Natural conditions of the region create a potential danger of soil erosion. The reason for its manifestation is the misuse of land, non-compliance with necessary requirements for soil protection. In most cases, it is due to the location of homesteads and crops on erosion-prone soils that poorly protect soil from erosion, improper cultivation of soils on arable land, unregulated grazing of pastures, and damage to soil protective plantations.


Author(s):  
Aleksandra Loba ◽  
Jarosław Waroszewski ◽  
Dmitry Tikhomirov ◽  
Fancesca Calitri ◽  
Marcus Christl ◽  
...  

Abstract Purpose Loess landscapes are highly susceptible to soil erosion, which affects soil stability and productivity. Erosion is non-linear in time and space and determines whether soils form or degrade. While the spatial variability of erosion is often assessed by either modelling or on-site measurements, temporal trends over decades to millennia are very often lacking. In this study, we determined long- and short-term erosion rates to trace the dynamics of loess deposits in south-western Poland. Materials and methods We quantified long-term (millennial) erosion rates using cosmogenic (in situ 10Be) and short-term (decadal) rates with fallout radionuclides (239+240Pu). Erosion processes were studied in two slope-soil transects (12 soil pits) with variable erosion features. As a reference site, an undisturbed soil profile under natural forest was sampled. Results and discussion The long-term erosion rates ranged between 0.44 and 0.85 t ha−1 year−1, whereas the short-term erosion rates varied from 1.2 to 10.9 t ha−1 year−1 and seem to be reliable. The short-term erosion rates are up to 10 times higher than the long-term rates. The soil erosion rates are quite consistent with the terrain relief, with erosion increasing in the steeper slope sections and decreasing in the lower parts of the slope, while still maintaining high values. Conclusions Soil erosion rates have increased during the last few decades owing to agriculture intensification and probably climate change. The measured values lie far above tolerable erosion rates, and the soils were found to be strongly imbalanced and exhibit a drastic shallowing of the productive soils horizons.


Author(s):  
V. P. Karpenko

Over the past decades, a third of the world’s arable land has been lost to soil erosion, and the rate of this degradation is increasing and will continue to increase with increasing production capacity boundaries. The persistent problem of soil erosion around the world has revived interest in perennial crops. All of our current crops are annuals, so developing a number of new perennial crops, legumes, and others will take a long-term effort. An analysis of the literary sources of domestic and foreign scientists has established that some cereals, such as rye, rice and sorghum, can be hybridized with the closest perennial relatives to enrich the gene pool. Others, such as wheat, oats, corn, soybeans and sunflowers, must be hybridized with more distant perennial species and genera. And some perennial species with a relatively high yield (medium wheatgrass, Maximilian sunflower and others) can be cultivated without interspecific hybridization.


2015 ◽  
Vol 12 (3) ◽  
pp. 2707-2740 ◽  
Author(s):  
S. C. Sherriff ◽  
J. S. Rowan ◽  
A. R. Melland ◽  
P. Jordan ◽  
O. Fenton ◽  
...  

Abstract. Soil erosion and suspended sediment (SS) pose risks to chemical and ecological water quality. Agricultural activities may accelerate erosional fluxes from bare, poached or compacted soils, and enhance connectivity through modified channels and artificial drainage networks. Storm-event fluxes dominate SS transport in agricultural catchments; therefore, high temporal-resolution monitoring approaches are required but can be expensive and technically challenging. Here, the performance of in situ turbidity-sensors, conventionally installed submerged at the river bankside, is compared with installations where river water is delivered to sensors ex situ, i.e. within instrument kiosks on the riverbank, at two experimental catchments (Grassland B and Arable B). Calibrated against storm-period depth-integrated SS data, both systems gave comparable results; using the ex situ and in situ methods respectively, total load at Grassland B was estimated at 128 ± 28 and 154 ± 35, and 225 ± 54 and 248 ± 52 t at Arable B. The absence of spurious turbidity peaks relating to bankside debris around the in situ sensor and its greater security, make the ex situ sensor more robust. The ex situ approach was then used to characterise SS dynamics and fluxes in five intensively managed agricultural catchments in Ireland which feature a range of landscape characteristics and land use pressures. Average annual suspended sediment concentration (SSC) was below the Freshwater Fish Directive (FFD) guideline of 25 mg L−1, and the continuous hourly record demonstrated that exceedance occurred less than 12% of the observation year. Soil drainage class and proportion of arable land were key controls determining flux rates, but all catchments reported a high degree of inter-annual variability associated with variable precipitation patterns compared to the long-term average. Poorly-drained soils had greater sensitivity to runoff and soil erosion, particularly in catchments with periods of bare soils. Well drained soils were less sensitive to erosion even on arable land; however, under extreme rainfall conditions, all bare soils remain a high sediment loss risk. Analysis of storm-period and seasonal dynamics (over the long term) using high resolution monitoring would be beneficial to further explore the impact of landscape, climate and land use characteristics on SS export.


2021 ◽  
Vol 264 ◽  
pp. 01004
Author(s):  
Gulnora Djalilova ◽  
Feruza Mamatkulova ◽  
Zamira Mamatkulova ◽  
Dilfuza Igamberdiyeva ◽  
Quvonchbek Eshquvatov

Rational use of natural resources and preservation of the environment in good conditions is the basis of the stable state of the ecosystem. Mountain soil erosion is the most common process of degradation. Soil protection from erosion is becoming a global problem in the world, and in Uzbekistan, in particular. Natural conditions of the region create a potential danger of soil erosion. The reason for its manifestation is the misuse of land, non-compliance with necessary requirements for soil protection. In most cases, it is due to the location of homesteads and crops on erosion-prone soils that poorly protect soil from erosion, improper cultivation of soils on arable land, unregulated grazing of pastures, and damage to soil protective plantations. The climate, topography and soils can in some way create a potential danger of erosion, while the vegetation cover reduces the possibility of erosion or completely prevents it. V.V.Dokuchaev [6] has given great importance to vegetation in the problems of soil protection from erosion and a decrease in the flow of atmospheric precipitation. He wrote: “… in the early spring, and after heavy rains in the virgin steppe there are no large streams, while on old-growth fields they run in all directions, storm and foam.” A good vegetation cover sharply reduces the danger of erosion when a great amount of precipitation falls out. With high intensity of rains on slopes with a good vegetation cover, the danger of erosion may be much less than in the case of rainfalls with a small amount of precipitation and with less intensity on slopes with poor plantation or without any.


2015 ◽  
Vol 19 (8) ◽  
pp. 3349-3363 ◽  
Author(s):  
S. C. Sherriff ◽  
J. S. Rowan ◽  
A. R. Melland ◽  
P. Jordan ◽  
O. Fenton ◽  
...  

Abstract. Soil erosion and suspended sediment (SS) pose risks to chemical and ecological water quality. Agricultural activities may accelerate erosional fluxes from bare, poached or compacted soils, and enhance connectivity through modified channels and artificial drainage networks. Storm-event fluxes dominate SS transport in agricultural catchments; therefore, high temporal-resolution monitoring approaches are required, but can be expensive and technically challenging. Here, the performance of in situ turbidity sensors, conventionally installed submerged at the river bankside, is compared with installations where river water is delivered to sensors ex situ, i.e. within instrument kiosks on the riverbank, at two experimental catchments (Grassland B and Arable B). The in situ and ex situ installations gave comparable results when calibrated against storm-period, depth-integrated SS data, with total loads at Grassland B estimated at 12 800 and 15 400 t, and 22 600 and 24 900 t at Arable B, respectively. The absence of spurious turbidity readings relating to bankside debris around the in situ sensor and its greater security make the ex situ sensor more robust. The ex situ approach was then used to characterise SS dynamics and fluxes in five intensively managed agricultural catchments in Ireland which feature a range of landscape characteristics and land use pressures. Average annual suspended sediment concentration (SSC) was below the Freshwater Fish Directive (78/659/EEC) guideline of 25 mg L−1, and the continuous hourly record demonstrated that exceedance occurred less than 12 % of the observation year. Soil drainage class and proportion of arable land were key controls determining flux rates, but all catchments reported a high degree of inter-annual variability associated with variable precipitation patterns compared to the long-term average. Poorly drained soils had greater sensitivity to runoff and soil erosion, particularly in catchments with periods of bare soils. Well drained soils were less sensitive to erosion even on arable land; however, under extreme rainfall conditions, all bare soils remain a high sediment loss risk. Analysis of storm-period and seasonal dynamics (over the long term) using high-resolution monitoring would be beneficial to further explore the impact of landscape, climate and land use characteristics on SS export.


Author(s):  
Ol'ga Gladysheva ◽  
Oksana Artyuhova ◽  
Vera Svirina

The results of long-term research in experiments with crop rotations with different clover saturation are presented. It is shown that the cluster has a positive effect on the main indicators of vegetation of dark-gray forest soil. The introduction of two fields of perennial grasses into the six-field crop rotation significantly increases both the humus reserves and increases the productivity of arable land by 1.5–2 times compared to the crop rotation with a field of pure steam.


2014 ◽  
Vol 18 (9) ◽  
pp. 3763-3775 ◽  
Author(s):  
K. Meusburger ◽  
G. Leitinger ◽  
L. Mabit ◽  
M. H. Mueller ◽  
A. Walter ◽  
...  

Abstract. Snow processes might be one important driver of soil erosion in Alpine grasslands and thus the unknown variable when erosion modelling is attempted. The aim of this study is to assess the importance of snow gliding as a soil erosion agent for four different land use/land cover types in a subalpine area in Switzerland. We used three different approaches to estimate soil erosion rates: sediment yield measurements in snow glide depositions, the fallout radionuclide 137Cs and modelling with the Revised Universal Soil Loss Equation (RUSLE). RUSLE permits the evaluation of soil loss by water erosion, the 137Cs method integrates soil loss due to all erosion agents involved, and the measurement of snow glide deposition sediment yield can be directly related to snow-glide-induced erosion. Further, cumulative snow glide distance was measured for the sites in the winter of 2009/2010 and modelled for the surrounding area and long-term average winter precipitation (1959–2010) with the spatial snow glide model (SSGM). Measured snow glide distance confirmed the presence of snow gliding and ranged from 2 to 189 cm, with lower values on the north-facing slopes. We observed a reduction of snow glide distance with increasing surface roughness of the vegetation, which is an important information with respect to conservation planning and expected and ongoing land use changes in the Alps. Snow glide erosion estimated from the snow glide depositions was highly variable with values ranging from 0.03 to 22.9 t ha−1 yr−1 in the winter of 2012/2013. For sites affected by snow glide deposition, a mean erosion rate of 8.4 t ha−1 yr−1 was found. The difference in long-term erosion rates determined with RUSLE and 137Cs confirms the constant influence of snow-glide-induced erosion, since a large difference (lower proportion of water erosion compared to total net erosion) was observed for sites with high snow glide rates and vice versa. Moreover, the difference between RUSLE and 137Cs erosion rates was related to the measured snow glide distance (R2 = 0.64; p < 0.005) and to the snow deposition sediment yields (R2 = 0.39; p = 0.13). The SSGM reproduced the relative difference of the measured snow glide values under different land uses and land cover types. The resulting map highlighted the relevance of snow gliding for large parts of the investigated area. Based on these results, we conclude that snow gliding appears to be a crucial and non-negligible process impacting soil erosion patterns and magnitude in subalpine areas with similar topographic and climatic conditions.


CATENA ◽  
2017 ◽  
Vol 151 ◽  
pp. 63-73 ◽  
Author(s):  
Samuel Bouchoms ◽  
Zhengang Wang ◽  
Veerle Vanacker ◽  
Sebastian Doetterl ◽  
Kristof Van Oost

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