Sediment‐bound nutrient export from five small reservoir catchments and its implications for the Sudan savanna zone of Ghana

Amegashie, Bright Kofi; Quansah, Charles; Agyare, Wilson Agyei; Tamene, Lulseged; Vlek, Paul L. G.

doi:10.1111/j.1440-1770.2011.00459.x

Cited by 17 publications

(15 citation statements)

References 20 publications

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“…In our case, the suspended sediments as well as the reservoir sediments showed significantly higher contents of MOC compared to the other sediment deposits, while the MOC contents in soils was similar to that in reservoir sediments and slightly higher than in suspended sediments. This was also found by Amegashie et al (2011) and can be probably attributed partially to new, in situ formation of OC in the reservoir (Einsele et al, 2001). We suggest that at these larger scales the decrease of OC in sediments compared to soils is due to a combination of factors related to the spatial scale of observation, namely (i) variety of sediment sources, that dilute the source effect; (ii) interaction of multiple erosion processes, both selective and unselective; (iii) long transport distances that favour continuous remobilisation of sediment facilitating aggregate breakdown and a reduced physical protection of OC; and (iv) the ample time lapse (from hours to several years) that occurred between sediment detachment and its sampling.…”

Section: Oc Redistribution: Effect Of the Scale Of Observationsupporting

confidence: 74%

Sediment flow paths and associated organic carbon dynamics across a Mediterranean catchment

Boix‐Fayos

Nadeu

Quiñonero

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Terrestrial sedimentation buries large amounts of organic carbon (OC) annually, contributing to the terrestrial carbon sink. The temporal significance of this sink will strongly depend on the attributes of the depositional environment, but also on the characteristics of the OC reaching these sites and its stability upon deposition. The goal of this study was to characterise the OC during transport and stored in the depositional settings of a mediumsized catchment (111 km 2 ) in SE Spain, to better understand how soil erosion and sediment transport processes determine catchment-scale OC redistribution. Total organic carbon (TOC), mineral-associated organic carbon (MOC), particulate organic carbon (POC), total nitrogen (N) and particle size distributions were determined for soils (i), suspended sediments (ii) and sediments stored in a variety of sinks such as sediment wedges behind check dams (iii), channel bars (iv), a small delta in the conjunction of the channel and a reservoir downstream (v), and the reservoir at the outlet of the catchment (vi). The data show that the OC content of sediments was approximately half of that in soils (9.42 ± 9.01 g kg −1 versus 20.45 ± 7.71 g kg −1 , respectively) with important variation between sediment deposits. Selectivity of mineral and organic material during transport and deposition increased in a downstream direction. The mineralisation, burial or in situ incorporation of OC in deposited sediments depended on their transport processes and on their post-sedimentary conditions. Upstream sediments (alluvial wedges) showed low OC contents because they were partially mobilised by non-selective erosion processes affecting deeper soil layers and with low selectivity of grain sizes (e.g. gully and bank erosion). We hypothesise that the relatively short transport distances, the effective preservation of OC in microaggregates and the burial of sediments in the alluvial wedges gave rise to low OC mineralisation, as is arguably indicated by C : N ratios similar to those in soils. Deposits in middle stream areas (fluvial bars) were enriched in sand, selected upon deposition and had low OC concentrations. Downstream, sediment transported over longer distances was more selected, poorly microaggregated, and with a prevalence of silt and clay fractions and MOC pool. Overall, the study shows that OC redistribution in the studied catchment is highly complex, and that the results obtained at finer scales cannot be extrapolated at catchment scale. Selectivity of particles during detachment and transport, and protection of OC during transport and deposition are key for the concentration and quality of OC found at different depositional settings. Hence, eco-geomorphological processes during the different phases of the erosion cycle have important consequences for the temporal stability and preservation of the buried OC and in turn for the OC budget.

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Section: Oc Redistribution: Effect Of the Scale Of Observationsupporting

confidence: 74%

Sediment flow paths and associated organic carbon dynamics across a Mediterranean catchment

Boix‐Fayos

Nadeu

Quiñonero

et al. 2015

Hydrol. Earth Syst. Sci.

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“…The high TOC L fluxes from forested areas can be explained by their preferential location on steep slopes of high MAP areas (Table ). The decrease of TOC L with soil clay content (Figure c) is consistent with results from several studies [e.g., Boix‐Fayos et al ., ; Amegashie et al ., ] and suggests greater protection of SOC as soil clay content increases. However, other factors, such as declining slope gradient and annual precipitation (Table ), may also help explain the trend.…”

Section: Discussionmentioning

confidence: 79%

Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta‐analysis as a function of scale

Mutema

Chaplot

Jewitt

et al. 2015

Water Resources Research

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“…The classic methods of soil management for erosion control have been successfully studied with good impacts on crop production and soil improvement (Bonsu and Quansah., 1992;Quansah et al, 2000;Amegashie et al, 2011;Chaghazardi, Jahansouz, Ahmadi, & Gorji, 2016;Wang et al, 2017) but with less attention given to effects of crop intensification on soil and water conservation (Govers, Merckx, Van Wesemael, & Van Oost, 2016). For farming systems, most of the methods of water and soil conservation have been developed based on the three principles of mulching, minimum tillage and crop rotation (Lal, 2001;Vanlauwe et al, 2013;Kurothe et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Soil loss and run‐off characteristics under different soil amendments and cropping systems in the semi‐deciduous forest zone of Ghana

Bashagaluke

Logah

Opoku

et al. 2019

Soil Use and Management

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Soil erosion is a major constraint to crop production on smallholder arable lands in Sub‐Saharan Africa (SSA). Although different agronomic and mechanical measures have been proposed to minimize soil loss in the region and elsewhere, soil management practices involving biochar‐inorganic inputs interactions under common cropping systems within the framework of climate‐smart agriculture, have been little studied. This study aimed to assess the effect of different soil and crop management practices on soil loss characteristics under selected cropping systems, typical of the sub‐region. A two‐factor field experiment was conducted on run‐off plots under different soil amendments over three consecutive cropping seasons in the semi‐deciduous forest zone of Ghana. The treatments, consisting of three soil amendments (inorganic fertilizer, biochar, inorganic fertilizer + biochar and control) and four cropping systems (maize, soyabean, cowpea, maize intercropped with soyabean) constituted the sub‐plot and main plot factors, respectively. A bare plot was included as a soil erosion check. Seasonal soil loss was greater on the bare plots, which ranged from 9.75–14.5 Mg ha−1. For individual crops grown alone, soil loss was 31%–40% less under cowpea than under maize. The soil management options, in addition to their direct role in plant nutrition, contributed to significant (p < 0.05) reductions in soil loss. The least soil loss (1.23–2.66 Mg ha−1) was observed under NPK fertilizer + biochar treatment (NPK + BC) over the three consecutive cropping seasons. Biochar in combination with NPK fertilizer improved soil moisture content under cowpea crops and produced considerably smaller bulk density values than most other treatments. The NPK + BC consistently outperformed the separate mineral fertilizer and biochar treatments in biomass yield under all cropping systems. Biochar associated with inorganic fertilizers gave economic returns with value–cost ratio (VCR) > 2 under soyabean cropping system but had VCR < 2 under all other cropping systems. The study showed that biochar/NPK interactions could be exploited in minimizing soil loss from arable lands in SSA.

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Sediment‐bound nutrient export from five small reservoir catchments and its implications for the Sudan savanna zone of Ghana

Cited by 17 publications

References 20 publications

Sediment flow paths and associated organic carbon dynamics across a Mediterranean catchment

Sediment flow paths and associated organic carbon dynamics across a Mediterranean catchment

Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta‐analysis as a function of scale

Soil loss and run‐off characteristics under different soil amendments and cropping systems in the semi‐deciduous forest zone of Ghana

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