Soil in Dogu'a Tembien explained

Soil in Dogu’a Tembien
Type:Soilscape
Period:Holocene
Prilithology:Clay, Loam
Otherlithology:Sand, Rocks
Region:Tigray
Coordinates:13.5°N 39.16°W
Thickness:2m (07feet)
Extent:Dogu’a Tembien

The soils of the Dogu’a Tembien woreda (district) in Tigray (Ethiopia) reflect its longstanding agricultural history, highly seasonal rainfall regime, relatively low temperatures, an extremely great variety in lithology (with dominance of basalts and limestone) and steep slopes. Outstanding features in the soilscape are the fertile highland Vertisols and Phaeozems in forests.[1] [2] [3] [4] [5]

Factors contributing to soil diversity

Climate

Annual rainfall depth is very variable with an average of around 800 mm.[6] Most rains fall during the main rainy season, which typically extends from June to September. Mean temperature in woreda town Hagere Selam is 16.8 °C, oscillating between average daily minimum of 9.3 °C and maximum of 24.1 °C. The contrasts between day and night air temperatures are much larger than seasonal contrasts.[7]

Geology

From the higher to the lower locations, the following geological formations are present:[8]

Topography

As part of the Ethiopian highlands the land has undergone a rapid tectonic uplift, leading the occurrence of mountain peaks, plateaus, valleys and gorges.

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.[12] [13] 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.[14] [15] [16] 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.

Hagere Selam Highlands

This land system occurs on the central basalt plateau and adjacent ridges; Hagere Selam is entirely in this land system, which is also predominant in tabias Selam, Mahbere Sillasie, Melfa, Lim'at, Seret, Simret, Mika'el Abiy as well as Arebay.

Basalt plateau

This land system occurs on the westernmost ridges of Dogu’a Tembien, where basalt is overlying Adigrat Sandstone without intervening Antalo Limestone; it is predominant in tabias Menachek, Mizan, Aregen and Degol Woyane.

Adigrat Sandstone cliff and footslope

This land system occurs on the steep slopes towards the southwestern lowlands; it occupies large areas of tabias Walta, Simret, Mizan, Aregen, Degol Woyane, Mahbere Sillasie and Haddinnet.

Alluvial plain of Giba River

This land system occurs in Kemishana at the southwestern side of Dogu’a Tembien, where the Giba River gorge widens up when entering into the Abergele lowlands.

Strongly incised Giba gorge

This land system occurs on in the deeply incised gorge of Giba River, at the lower side of tabias Walta, Inda Sillasie, Amanit and Debre Nazret.

Gently rolling Antalo Limestone plateau, holding cliffs and valley bottoms

This land system occurs on Antalo Limestone, it is predominant in tabias Walta, Inda Sillasie, Ayninbirkekin, Amanit and Debre Nazret.

This land system occurs on Agula Shale at the east of Dogu’a Tembien, it is predominant in tabias Addi Azmera, Mizane Birhan and parts of Debre Nazret, Haddinnet and Addilal.

This land system occurs on Antalo Limestone; it is predominant in tabias Emni Ankelalu and Addilal.

Giba wide valley bottom

This land system occurs where the Giba valley widens; it occurs only at the lower places of tabia Emni Ankelalu and will be flooded once the Lake Giba reservoir will be filled.

Soil erosion and conservation

The reduced soil protection by vegetation cover, combined with steep slopes and erosive rainfall has led to excessive soil erosion.[12] [17] [18] 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.[19] [20] 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.[21] [22]

Measures include the construction of infiltration trenches, stone bunds,[23] check dams,[24] small reservoirs such as Chini and May Leiba as well as a major biological measure: exclosures in order to allow forest regeneration.[3] 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]

Notes and References

  1. Nyssen. Jan. Tielens. Sander. Gebreyohannes. Tesfamichael. Araya. Tigist. Teka. Kassa. Van De Wauw. Johan. Degeyndt. Karen. Descheemaeker. Katrien. Amare. Kassa. Haile. Mitiku. Zenebe. Amanuel. Munro. Neil. Walraevens. Kristine. Gebrehiwot. Kindeya. Poesen. Jean. Frankl. Amaury. Tsegay. Alemtsehay. Deckers. Jozef. Understanding spatial patterns of soils for sustainable agriculture in northern Ethiopia's tropical mountains. . PLOS ONE . 2019 . 14 . 10 . e0224041 . 10.1371/journal.pone.0224041. 31639144. 6804989. 2019PLoSO..1424041N. free.
  2. Nyssen. J.. Naudts. J.. De Geyndt. K.. Haile. Mitiku. Poesen. J.. Moeyersons. J.. Deckers. J.. Soils and land use in the Tigray highlands (Northern Ethiopia). . Palaeogeography, Palaeoclimatology, Palaeoecology . 2008 . 19 . 3 . 257–274 . 10.1002/ldr.840. 128492271.
  3. Descheemaeker . K. and colleagues . Sediment deposition and pedogenesis in exclosures in the Tigray Highlands, Ethiopia. . Geoderma . 2006 . 132 . 3–4. 291–314 . 10.1016/j.geoderma.2005.04.027 . 2006Geode.132..291D .
  4. Van de Wauw . J. and colleagues . Soil-landscape relationships in the basalt-dominated highlands of Tigay, Ethiopia. . Catena . 2008 . 75 . 117–127 . 10.1016/j.catena.2008.04.006 .
  5. Book: Hunting Technical Services . Central Tigre Development Study – Tigre Province Ethiopia, Working Paper I: Soils and land classification. . Hunting Technical Services Ltd. . Hemel Hempstead (U.K.).
  6. Jacob . M. and colleagues . Assessing spatio-temporal rainfall variability in a tropical mountain area (Ethiopia) using NOAAs Rainfall Estimates. . International Journal of Remote Sensing . 2013 . 34 . 23 . 8305–8321 . 10.1080/01431161.2013.837230 . 2013IJRS...34.8319J . 140560276 . 1854/LU-4252226 . free .
  7. Book: Jacob . M. and colleagues . Dogu'a Tembien's Tropical Mountain Climate. In: Geo-trekking in Ethiopia's Tropical Mountains — The Dogu'a Tembien District . 2019 . SpringerNature . 978-3-030-04954-6 . 10.1007/978-3-030-04955-3_3 . 199105560 .
  8. Book: Sembroni . A. . Molin . P. . Dramis . F. . Regional geology of the Dogu'a Tembien massif. In: Geo-trekking in Ethiopia's Tropical Mountains — The Dogu'a Tembien District . 2019 . SpringerNature . 978-3-030-04954-6 .
  9. Bosellini . A. . Russo . A. . Fantozzi . P. . Assefa . G. . Tadesse . S. . The Mesozoic succession of the Mekelle Outlier (Tigrai Province, Ethiopia). . Mem. Sci. Geol. . 1997 . 49 . 95–116.
  10. Book: Tefera . M. . Chernet . T. . Haro . W. . Geological Map of Ethiopia (1:2,000,000). . Ethiopian Institute of Geological Survey . Addis Ababa, Ethiopia.
  11. Moeyersons . J. and colleagues . Age and backfill/overfill stratigraphy of two tufa dams, Tigray Highlands, Ethiopia: Evidence for Late Pleistocene and Holocene wet conditions. . Palaeogeography, Palaeoclimatology, Palaeoecology . 2006 . 230 . 1–2 . 162–178 . 2006PPP...230..165M . 10.1016/j.palaeo.2005.07.013 .
  12. Nyssen. Jan. Poesen. Jean. Moeyersons. Jan. Deckers. Jozef. Haile. Mitiku. Lang. Andreas. Human impact on the environment in the Ethiopian and Eritrean highlands - a state of the art. . Earth-Science Reviews . 2004 . 64 . 3–4 . 273–320 . 10.1016/S0012-8252(03)00078-3. 2004ESRv...64..273N.
  13. Blond . N. and colleagues . Terrasses alluviales et terrasses agricoles. Première approche des comblements sédimentaires et de leurs aménagements agricoles depuis 5000 av. n. è. à Wakarida (Éthiopie). . Géomorphologie: Relief, Processus, Environnement . 2018 . 24 . 3 . 277–300 . 10.4000/geomorphologie.12258 . 134513245 .
  14. Bui . E.N. . Soil survey as a knowledge system. . Geoderma. . 2004 . 120 . 1–2 . 17–26 . 10.1016/j.geoderma.2003.07.006 . 2004Geode.120...17B .
  15. Principes de la cartographie des pédopaysages dans les Alpes. . Écologie . 1998 . 29 . 1–2 . 49 . .
  16. Book: Tielens . Sander . Towards a soil map of the Geba catchment using benchmark soils. MSc thesis.. 2012 . K.U.Leuven . Leuven, Belgium .
  17. Demel Teketay . Deforestation, wood famine, and environmental degradation in Ethiopia's highland ecosystems: urgent need for action. . Northeast African Studies . 2001 . 8 . 1. 53–76 . 41931355. 10.1353/nas.2005.0020. 145550500 .
  18. Nyssen. Jan. Frankl. Amaury. Zenebe. Amanuel. Deckers. Jozef. Poesen. Jean. Land management in the northern Ethiopian highlands: local and global perspectives; past, present and future. . Land Degradation & Development . 2015 . 26 . 7 . 759–794 . 10.1002/ldr.2336. 129501591.
  19. Book: Vancampenhout . K. and colleagues . Sheet and Rill Erosion and Its Control: Lessons from Dogu'a Tembien. In: Geo-trekking in Ethiopia's Tropical Mountains — The Dogu'a Tembien District . 2019 . SpringerNature . 978-3-030-04954-6 . 10.1007/978-3-030-04955-3_21 . 199110301 .
  20. Book: Frankl . A. and colleagues . Gully Erosion and Control in the Tembien Highlands. In: Geo-trekking in Ethiopia's Tropical Mountains — The Dogu'a Tembien District . 2019 . SpringerNature . 978-3-030-04954-6 . 10.1007/978-3-030-04955-3_22 . 199099185 .
  21. Book: Farmland Management, Tillage and Resulting Cultivation Terraces. In: Geo-trekking in Ethiopia's Tropical Mountains — The Dogu'a Tembien District . 2019 . SpringerNature . 978-3-030-04954-6 . 10.1007/978-3-030-04955-3_26. 199097368 .
  22. Book: Reubens . B. and colleagues . Research-Based Development Projects in Dogu'a Tembien. In: Geo-trekking in Ethiopia's Tropical Mountains — The Dogu'a Tembien District . 2019 . SpringerNature . 978-3-030-04954-6 . 10.1007/978-3-030-04955-3_30 . 199261393 .
  23. Nyssen. Jan. Poesen. Jean. Gebremichael. Desta. Vancampenhout. Karen. d'Aes. Margo. Yihdego. Gebremedhin. Govers. Gerard. Leirs. Herwig. Moeyersons. Jan. Naudts. Jozef. Haregeweyn. Nigussie. Haile. Mitiku. Deckers. Jozef. Interdisciplinary on-site evaluation of stone bunds to control soil erosion on cropland in Northern Ethiopia. . Soil and Tillage Research . 2007 . 94 . 1 . 151–163 . 10.1016/j.still.2006.07.011. 1854/LU-378900. free.
  24. Nyssen. J.. Veyret-Picot. M.. Poesen. J.. Moeyersons. J.. Haile. Mitiku. Deckers. J.. Govers. G.. The effectiveness of loose rock check dams for gully control in Tigray, Northern Ethiopia. . Soil Use and Management . 2004 . 20 . 55–64 . 10.1111/j.1475-2743.2004.tb00337.x. 98547102.
  25. Tewodros Gebreegziabher . and colleagues . Contour furrows for in situ soil and water conservation, Tigray, Northern Ethiopia. . Soil and Tillage Research . 2009 . 103 . 2 . 257–264 . 10.1016/j.still.2008.05.021 .

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