Soil Organic Matter Dynamics in the Subhumid Agroecosystems of the Ethiopian Highlands

Solomon, Daniel; Fritzsche, Florian; Lehmann, Johannes; Tekalign, Meron; Zech, Wolfgang

doi:10.2136/sssaj2002.0969

Cited by 78 publications

(83 citation statements)

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“…Soil C (g m -2 ) stock for each sampled depth was calculated using the following equation: (2) where, zcorr = adjusted thickness of a sample soil layers under plantation or farmland, ?forest = bulk density of the sampled soil layer under the natural forest, ?LU = bulk density of the sampled soil layers under plantation or farmland, z = thickness of soil layers used during field sampling (Dawit Solomon et al, 2002). The average annual accrual (rates of accumulation) of soil C and total N under the plantations were calculated after dividing the difference in soil C or total N stocks (g m -2 ) in the soils of the plantations and the farmland by the age of the respective plantation.…”

Section: Discussionmentioning

confidence: 99%

Changes in soil carbon and total nitrogen following reforestation of previously cultivated land in the highlands of Ethiopia

Lemenih¹,

Lemma²,

Teketay

2006

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Changes in soil C and total N stocks were investigated following reforestation of previously cultivated soil in compariso n with soil subjected to continuous cultivation and soil under an adjacent natural forests in south central highlands of Ethiopia. Two of the most widely planted tree species in the highlands of Ethiopia, namely Eucalyptus saligna and Cupressus lusitanica, were considered in the plantation treatments. Soil C and total N contents in the upper 0-10 and 10-20 cm soil layers were significantly different in the order: Natural forest > C. lusitanica > E. saligna > Farmland. Differences in soil C and total N contents among the sites for soil depths greater than 20 cm were negligibly small and statistically not significant. Soil C and total N stocks in the upper 0.80 m mineral soil also varied significantly in the same order as above. Estimated average annual soil C accruals were 156 and 37 g C m -2 yr -1 for Cupressus lusitanica and Eucalyptus saligna, respectively. The results demonstrate that reforestation of former arable soils in the dry Afromontane region of Ethiopia could yield significant restoration of soil C and total N that are lost in the process of natural forest conversion into arable lands and subsequent cultivation. However, the two plantation species differed considerably with respect to the rate of soil C and total N accrual. This suggests that proper selection of tree species will considerably affect the magnitude and rate of soil C sequestration.

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Section: Discussionmentioning

confidence: 99%

Changes in soil carbon and total nitrogen following reforestation of previously cultivated land in the highlands of Ethiopia

Lemenih¹,

Lemma²,

Teketay

2006

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“…Andosol soil type and its subsequent conversion into low-input agricultural systems are responsible for the lowest amount of SOC stock (Solomon et al, 2002;Emiru and Gebrekidan, 2013). For example, within similar elevation and amount of rainfall, significance differences of SOC stocks were observed in the Andosols of Alaba (14.4 Mg C ha -1 ) and Vertisol of Debrezit area (33.9 Mg C ha -1 ).…”

Section: Sub-humid Agroecosystemsmentioning

confidence: 99%

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

2017

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Soils represent the largest carbon pool and play important roles for carbon storage for prolonged periods in agroecosystems. A number of studies were conducted to quantify soil organic carbon (SOC) worldwide. The objective of this review was to evaluate organic carbon stocks, dynamics and restoration in soils of agroecosystems in Ethiopia. Soil data from 32 different observations, representing four different agroecosystems, were analysed. The mean SOC stocks in the four agroecosystems varied and ranged from 25.66 (sub-humid agroecosystem) to 113.17 (humid midhighland agroecosystems) Mg C ha -1 up to one meter depth. The trend of mean SOC followed (in descending order): humid mid-highland (113.17 Mg C ha -1 ) > per-humid highland (57.14 Mg C ha -1 ) > semi-arid (25.77 Mg C ha -1 ) > sub-humid (25.66 Mg C ha -1 ). Compared with soils of tropical countries, those in Ethiopian agroecosystems contained low SOC storage potential. This might be associated with differences in measurement and analysis methods as 53.1% of the studies employed the Walkley-Black Method, which is known to underestimate carbon stocks in addition to ecological and management effects. However, shifts of land management from rain-fed to irrigation farming systems exhibited progress in the improvement of mean SOC storage potential. The analyses showed that farming systems involving irrigation sequestered more carbon than rain-fed farm systems. The mean SOC in the various agricultural land uses followed the following trend (in descending order): agroforestry (153.57 Mg C ha -1 ) > grazing land (34.61 Mg C ha -1 ) > cereal cultivation (24.18 Mg C ha -1 ). Therefore, the possible solutions for improvement of organic carbon stocks would be implementation of appropriate restoration strategies based on agroecosystems.

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“…Amelung et al, 1999;Jimenez et al, 2011;Rumpel et al, 2000;Sa et al, 2001;Schmidt et al, 1999b;Solomon et al, 2000Solomon et al, , 2002 was based on the assumption that the state of decomposition of associated SOM should be a function of particle size as decay induces fragmentation. This procedure does not allow to segregate plant debris (free OM) from more processed and protected mineral-bound OM.…”

Section: Moni Et Al: Density Fractions Versus Size Separatesmentioning

confidence: 99%

Density fractions versus size separates: does physical fractionation isolate functional soil compartments?

et al. 2012

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Abstract. Physical fractionation is a widely used methodology to study soil organic matter (SOM) dynamics, but concerns have been raised that the available fractionation methods do not well describe functional SOM pools. In this study we explore whether physical fractionation techniques isolate soil compartments in a meaningful and functionally relevant way for the investigation of litter-derived nitrogen dynamics at the decadal timescale. We do so by performing aggregate density fractionation (ADF) and particle size-density fractionation (PSDF) on mineral soil samples from two European beech forests a decade after application of 15 N labelled litter.Both density and size-based fractionation methods suggested that litter-derived nitrogen became increasingly associated with the mineral phase as decomposition progressed, within aggregates and onto mineral surfaces. However, scientists investigating specific aspects of litter-derived nitrogen dynamics are pointed towards ADF when adsorption and aggregation processes are of interest, whereas PSDF is the superior tool to research the fate of particulate organic matter (POM).Some methodological caveats were observed mainly for the PSDF procedure, the most important one being that fine fractions isolated after sonication can not be linked to any defined decomposition pathway or protective mechanism. This also implies that historical assumptions about the "adsorbed" state of carbon associated with fine fractions need to be reevaluated. Finally, this work demonstrates that establishing a comprehensive picture of whole soil OM dynamics requires a combination of both methodologies and we offer a suggestion for an efficient combination of the density and size-based approaches.

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Soil Organic Matter Dynamics in the Subhumid Agroecosystems of the Ethiopian Highlands

Cited by 78 publications

References 0 publications

Changes in soil carbon and total nitrogen following reforestation of previously cultivated land in the highlands of Ethiopia

Changes in soil carbon and total nitrogen following reforestation of previously cultivated land in the highlands of Ethiopia

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

Density fractions versus size separates: does physical fractionation isolate functional soil compartments?

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