Soil in Inderta
The soils of the Inderta woreda (district) in Tigray (Ethiopia) reflect its longstanding agricultural history, highly seasonal rainfall regime, relatively low temperatures, overall dominance of limestone and dolerite lithologies and steep slopes. Outstanding features in the soilscape are wide plains with Vertisols.[1][2][3][4]
Factors contributing to soil diversity
Climate
Annual rainfall depth is very variable with an average of around 600 mm.[5] Most rains fall during the main rainy season, which typically extends from June to September. Mean temperature in woreda town Kwiha is 20 °C, oscillating between average daily minimum of 11.3 °C and maximum of 28.4 °C. The contrasts between day and night air temperatures are much larger than seasonal contrasts.[6]
Geology
From the higher to the lower locations, the following geological formations are present:[7]
- Amba Aradam Formation
- Agula Shale[8]
- Mekelle Dolerite[9]
- Antalo Limestone
- Quaternary alluvium and freshwater tufa[10]
Topography
As part of the
Land use
Generally speaking the level lands and intermediate slopes are occupied by cropland, while there is rangeland and shrubs on the steeper slopes. Remnant forests occur around Orthodox Christian churches and a few inaccessible places. A recent trend is the widespread planting of eucalyptus trees.
Environmental changes
Soil degradation in this district became important when humans started deforestation almost 5000 years ago.[11][12] Depending on land use history, locations have been exposed in varying degrees to such land degradation.
Geomorphic regions and soil units
Given the complex geology and topography of the district, it has been organised into land systems - areas with specific and unique geomorphic and geological characteristics, characterised by a particular soil distribution along the soil catena.[13][14][15] Soil types are classified in line with World Reference Base for Soil Resources and reference made to main characteristics that can be observed in the field.
Gently rolling Antalo Limestone plateau, holding cliffs and valley bottoms
- Associated soil types
- Inclusions
Gently undulating Agula dolerite
- Dominant soil type: stony, dark cracking clays with good natural fertility (Vertic Cambisol) (10)
- Associated soil types
- Inclusions
Mekelle Graben
- Associated soil types
- Inclusions
Strongly incised Giba gorge
- Dominant soil type: complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
- Associated soil types
Ancient river terraces
- Associated soil types
- shallow, stony, dark, loamy soils on calcaric material (Rendzic Leptosol) (3)
- Deep, dark cracking clays with good fertility, but problems of waterlogging (Chromic and Pellic Vertisol) (12)
- moderately deep, red-brownish, loamy soils with a good natural fertility (Chromic Luvisol) (20)
- Brown to dark, silty clay loams to loamy sands developed on alluvium, with good natural fertility (Fluvisol) (30)
- Inclusions
Alluvial plains induced by tufa dams
- Dominant soil type: deep dark cracking clays with very good natural fertility, waterlogged during the wet season (Chromic Vertisol, Pellic Vertisol) (12)
- Associated soil type: stony, dark cracking clays with good natural fertility (Vertic Cambisol) (10)
- Inclusions
Soil erosion and conservation
The reduced soil protection by vegetation cover, combined with steep slopes and erosive rainfall has led to excessive soil erosion.[11][16][17] Nutrients and organic matter were lost and soil depth was reduced. Hence, soil erosion is an important problem, which results in low crop yields and biomass production.[18][19] As a response to the strong degradation and thanks to the hard labour of many people in the villages, soil conservation has been carried out on a large scale since the 1980s and especially 1980s; this has curbed rates of soil loss.[20][21] Measures include the construction of infiltration trenches, stone bunds,[22] check dams,[23] small reservoirs such as Addi Amharay, Arato and Hiza'iti Wedi Cheber as well as a major biological measure: exclosures in order to allow forest regeneration.[24] On the other hand, it remains difficult to convince farmers to carry out measures within the farmland (in situ soil management), such as bed and furrows or zero grazing, as there is a fear for loss of income from the land. Such techniques are however very effective.[25]
References
- PMID 31639144.
- ^ Hunting Technical Services. Central Tigre Development Study – Tigre Province Ethiopia, Working Paper I: Soils and land classification. Hemel Hempstead (U.K.): Hunting Technical Services Ltd.
- ^ IAO (2008). Land evaluation in Enderta District - Tigray Region, Ethiopia. Firenze, Italy: Ministry of Foreign Affairs, Istituto Agronomico per l'Oltremare.
- ^ IAO (2014). Land evaluation in the May Gabat watershed Enderta-Hintalo Wejirat Districts (Northern Ethiopia). Firenze, Italy: Ministry of Foreign Affairs, Istituto Agronomico per l'Oltremare.
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- ISBN 978-3-030-04954-6.
- ^ Bosellini, A.; Russo, A.; Fantozzi, P.; Assefa, G.; Tadesse, S. (1997). "The Mesozoic succession of the Mekelle Outlier (Tigrai Province, Ethiopia)". Mem. Sci. Geol. 49: 95–116.
- ^ Tefera, M.; Chernet, T.; Haro, W. Geological Map of Ethiopia (1:2,000,000). Addis Ababa, Ethiopia: Ethiopian Institute of Geological Survey.
- .
- ^ .
- S2CID 134513245.
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- ProQuest 223074690.
- ^ Tielens, Sander (2012). Towards a soil map of the Geba catchment using benchmark soils. MSc thesis. Leuven, Belgium: K.U.Leuven.
- S2CID 145550500.
- S2CID 129501591.
- S2CID 30898575.
- S2CID 140536258.
- ^ Fitsum Hagos, and colleagues (1999). Land degradation in the Highlands of Tigray and strategies for sustainable land management (No. 25) (PDF). ILRI.
- S2CID 199104514.
- hdl:1854/LU-378900.
- S2CID 98547102.
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