Organic Carbon Stocks, Dynamics and Restoration in Relation to Soils of Agroecosystems in Ethiopia: A Review

Gebeyehu, Getaneh; Soromessa, Teshome; Teketay, Demel

doi:10.3126/ije.v6i1.16864

Cited by 14 publications

(7 citation statements)

References 28 publications

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“…However, our results were consistent with studies which showed that the establishment of enclosures on previously degraded semi-arid grassland increased the emission of CO 2 from soil [66, 67]. The high CO 2 flux rate in the older enclosures (> 20 years), could be due to the dominance of perennial grasses which have greater root biomass than annual grasses and forbs and produce more root exudates and substrates [67], which supported microbial respiration activities in soil.…”

Section: Discussionsupporting

confidence: 92%

Pasture enclosures increase soil carbon dioxide flux rate in Semiarid Rangeland, Kenya

Oduor

Karanja

Onwonga

et al. 2018

Carbon Balance Manage

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BackgroundPasture enclosures play an important role in rehabilitating the degraded soils and vegetation, and may also influence the emission of key greenhouse gasses (GHGs) from the soil. However, no study in East Africa and in Kenya has conducted direct measurements of GHG fluxes following the restoration of degraded communal grazing lands through the establishment of pasture enclosures. A field experiment was conducted in northwestern Kenya to measure the emission of CO2, CH4 and N2O from soil under two pasture restoration systems; grazing dominated enclosure (GDE) and contractual grazing enclosure (CGE), and in the adjacent open grazing rangeland (OGR) as control. Herbaceous vegetation cover, biomass production, and surface (0–10 cm) soil organic carbon (SOC) were also assessed to determine their relationship with the GHG flux rate.ResultsVegetation cover was higher enclosure systems and ranged from 20.7% in OGR to 40.2% in GDE while aboveground biomass increased from 72.0 kg DM ha−1 in OGR to 483.1 and 560.4 kg DM ha−1 in CGE and GDE respectively. The SOC concentration in GDE and CGE increased by an average of 27% relative to OGR and ranged between 4.4 g kg−1 and 6.6 g kg−1. The mean emission rates across the grazing systems were 18.6 μg N m−2 h−1, 50.1 μg C m−2 h−1 and 199.7 mg C m−2 h−1 for N2O, CH4, and CO2, respectively. Soil CO2 emission was considerably higher in GDE and CGE systems than in OGR (P < 0.001). However, non-significantly higher CH4 and N2O emissions were observed in GDE and CGE compared to OGR (P = 0.33 and 0.53 for CH4 and N2O, respectively). Soil moisture exhibited a significant positive relationship with CO2, CH4, and N2O, implying that it is the key factor influencing the flux rate of GHGs in the area.ConclusionsThe results demonstrated that the establishment of enclosures in tropical rangelands is a valuable intervention for improving pasture production and restoration of surface soil properties. However, a long-term study is required to evaluate the patterns in annual CO2, N2O, CH4 fluxes from soils and determine the ecosystem carbon balance across the pastoral landscape.

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Section: Discussionsupporting

confidence: 92%

Pasture enclosures increase soil carbon dioxide flux rate in Semiarid Rangeland, Kenya

Oduor

Karanja

Onwonga

et al. 2018

Carbon Balance Manage

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Section: Stockssupporting

confidence: 84%

“…The total SOC stocks at soil depth for the three land use systems in this study were within the range of SOC stocks reported for other similar systems in Ethiopia 50 . The upper layer (0-30 cm depth) SOC stock of FFI in this study area was higher than the mean SOC (65.2 Mg C ha -1 ) of Nitisol soil under agroforestry systems in Ethiopia 50 . The result of SOC in 0-30 systems cm depth in FFI was also higher than the 0-30 cm depth SOC recorded in Gununo watershed agroforestry practices 51 , and 0-30 cm depth SOC (60.8 Mg C ha -1 ) of Indonesia homegarden agroforestry system 52 .…”

Section: Stockssupporting

confidence: 84%

Conversion of natural forests to farmlands and its associated woody species diversity and carbon stocks in a span of 33 years (1984 to 2016): in the case of southwestern Ethiopia

2021

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Background Gura-Ferda forest is one of the Afromontane rainforests in the southwestern region of Ethiopia. However, since 1984, large parts of this forest have become increasingly disturbed and fragmented due to forest conversion into forest farm interface and farmlands. The study was conducted to assess changes of woody species diversity and carbon stock in association with the conversion of natural forest to forest farm interface and farmlands. Methods Data were collected from natural forest, forest farm interface and farmland which are historically forest lands before 1984. A total of 90 nested plots (20m×20m for natural forest and forest farm interface; 50m*100m for farmland)) were established for inventory of woody species. Three 1m×1m subplots were established to collect litter and soil samples. A total of 180 soil samples were collected. The total carbon stocks were estimated by summing carbon stock in the biomass and soil (0-60 cm depth). Results Results showed that Shannon-Wiener diversity (H’) in forest farm interface (H’ = 1.42±0.49) is significantly lower than that of natural forest (H’ = 2.72±0.31) but significantly higher than farmland (H’ = 1.08±0.57). The total carbon stocks of natural forest (388.54±161.63 Mg C ha-1) were approximately 1.53 and 2.67 times higher than that of forest farm interface (252.95±41.86 Mg C ha-1) and farmland (145.58±25.94 Mg C ha-1). Conclusion Our study revealed that along the conversion gradient of natural forest to forest farm interface and farmland there was a significant change of woody species diversity and carbon stocks.

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“…Detailed overview of different techniques employed in modern times for SOC determination is well presented by Chatterjee et al (2009). Despite the wide usage of the "traditional" Walkley and Black (WB) method, due to its procedural simplicity (Wang et al 2012), it has been heavily criticized due to its limitations, which include incomplete combustion, variations in oxidation of various forms of SOC by dichromate, high cost of chemicals used for the analysis, and considerable low efficiency in C determination (FAO 2001(FAO , 2007Gelman et al 2012;Amare et al 2013;Gebeyehu et al 2017). Nevertheless, more accurate, precise, and cost-effective measurement of SOC is required in C sequestration programs in terrestrial ecosystems in view of ensuring accurate quantification, verification, and monitoring of potential SOC stocks over time.…”

Section: Uncertainties In Soil Organic Carbon Studiesmentioning

confidence: 99%

Advances in quantifying soil organic carbon under different land uses in Ethiopia: a review and synthesis

et al. 2019

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Background: In the face of climate change and global warming, scientists globally are striving for effective techniques on how best to sequester carbon in order to reduce global warming and achieve environmental sustainability. This paper reviews the available literature on the influence of various land use changes on gains and/ or losses of soil carbon (C) stocks in Ethiopia. Results: Our review indicated that 33.3% of the studies reported soil organic carbon (SOC) concentration, 13.9% reported only SOC stock while 52.8% reported both SOC concentration and stock. Studies focusing on 0-30 cm only were 44%, other studies extending up to 40 to 100 cm were 50%, and studies extending to more than 100 cm accounted for 2.8% while studies without any depth specification accounted for 2.8%. Irrespective of soil type, C stocks in the top soil (0-30 cm) were found to be higher than at subsoil depths. Even though there is significant improvement in C sequestration in exclosures and community forests, the level of C sequestered is still below that of church forests. Conclusion: Conversion of native forest to other land uses resulted in a significant decrease in the SOC stocks across Ethiopia. Absence of long-term field trials and non-existence of SOC database are among the major drawbacks of SOC studies in Ethiopia identified in this review. With better management practices, it is possible to restore depleted C concentrations and stocks even in degraded lands and to conserve C in more pristine lands across the rugged landscapes of Ethiopia.

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Organic Carbon Stocks, Dynamics and Restoration in Relation to Soils of Agroecosystems in Ethiopia: A Review

Cited by 14 publications

References 28 publications

Pasture enclosures increase soil carbon dioxide flux rate in Semiarid Rangeland, Kenya

Pasture enclosures increase soil carbon dioxide flux rate in Semiarid Rangeland, Kenya

Conversion of natural forests to farmlands and its associated woody species diversity and carbon stocks in a span of 33 years (1984 to 2016): in the case of southwestern Ethiopia

Advances in quantifying soil organic carbon under different land uses in Ethiopia: a review and synthesis

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