Soil in Kilte Awula'ilo explained

The soils of the Kilte Awula’ilo woreda (district) in Tigray, Ethiopia reflect its longstanding agricultural history, highly seasonal rainfall regime, relatively low temperatures, the presence of a wide depression at the foot of the Atsbi horst and steep slopes. Outstanding features in the soilscape are the wide ancient fluvial deposits, the soils of the granite batholith, cuestas and fertile lands behind tufa dams.[1] [2] [3]

Factors contributing to soil diversity

Climate

Annual rainfall depth is very variable with an average of around 600 mm.[4] Most rains fall during the main rainy season, which typically extends from June to September. Mean temperature in woreda town Wuqro is 22.2 °C, oscillating between average daily minimum of 12.6 °C and maximum of 31.1 °C. The contrasts between day and night air temperatures are much larger than seasonal contrasts.[5]

Geology

The following geological formations are present:

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.[8] [9] 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.[10] [11] [12] 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.

Wuqro fluvial landscape

Deeply incised mountainous area (escarpment towards Atsbi)

Ancient river terraces

Alluvial plains induced by tufa dams

Incised Agula Shale plateau

Gently rolling Antalo Limestone plateau, holding cliffs and valley bottoms

Cuesta landscape

Atsaf and Menda’i plains

Suluh plains with metavolcanic rocks

Circular granite batholith (intrusive)

Soil erosion and conservation

The reduced soil protection by vegetation cover, combined with steep slopes and erosive rainfall has led to excessive soil erosion.[8] [13] [14] 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.[15] Given the strong degradation and thanks to the hard labour of many people in the villages, soil conservation is carried out on a large scale since the 1980s and especially 1980s; this has curbed rates of soil loss.[16] Measures include the construction of infiltration trenches, stone bunds,[17] check dams,[18] small reservoirs such as La'ilay Wuqro and May Azaboy as well as a major biological measure: exclosures in order to allow forest regeneration.[19] 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.[20]

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. 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.).
  3. Book: IAO . Land evaluation in Kilte Awulaelo - Tigray Region, Ethiopia.. 2009 . Ministry of Foreign Affairs, Istituto Agronomico per l'Oltremare . Firenze, Italy .
  4. Assessing spatio-temporal rainfall variability in a tropical mountain area (Ethiopia) using NOAA's rainfall estimates. Miro. Jacob. Amaury. Frankl. Mitiku. Haile. Ann. Zwertvaegher. Jan. Nyssen. December 10, 2013. International Journal of Remote Sensing. 34. 23. 8319–8335. Taylor and Francis+NEJM. 10.1080/01431161.2013.837230. 1854/LU-4252226 . 140560276 . free.
  5. Book: Geo-trekking in Ethiopia's Tropical Mountains. Jan. Nyssen. Miro. Jacob. Amaury. Frankl. 2019. 978-3-030-04954-6.
  6. 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.
  7. Age and backfill/overfill stratigraphy of two tufa dams, Tigray Highlands, Ethiopia: Evidence for Late Pleistocene and Holocene wet conditions. Jan. Moeyersons. Jan. Nyssen. Jean. Poesen. Jozef. Deckers. Mitiku. Haile. January 17, 2006. Palaeogeography, Palaeoclimatology, Palaeoecology. 230. 1. 165–181. ScienceDirect. 10.1016/j.palaeo.2005.07.013.
  8. 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.
  9. 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 .
  10. 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 .
  11. Principes de la cartographie des pédopaysages dans les Alpes . Écologie . 1998 . 29 . 1–2 . 49 . .
  12. Book: Tielens . Sander . Towards a soil map of the Geba catchment using benchmark soils. MSc thesis.. 2012 . K.U.Leuven . Leuven, Belgium .
  13. 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 .
  14. 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.
  15. Ayele Almaw. and colleagues. Dynamics of soil erosion as influenced by watershed management practices: a case study of the Agula watershed in the semi-arid highlands of northern Ethiopia. . Environmental Management . 2016 . 58 . 5 . 889–905 . 10.1007/s00267-016-0757-4. 27605225. 2016EnMan..58..889F. 4553654.
  16. Walraevens. K. and colleagues. Water balance components for sustainability assessment of groundwater‐dependent agriculture: example of the Mendae Plain (Tigray, Ethiopia). . Land Degradation & Development . 2015 . 26 . 7 . 725–736 . 10.1002/ldr.2377. 140148682.
  17. 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.
  18. 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.
  19. Sediment deposition and pedogenesis in exclosures in the Tigray highlands, Ethiopia. Katrien. Descheemaeker. Jan. Nyssen. Joni. Rossi. Jean. Poesen. Mitiku. Haile. Dirk. Raes. Bart. Muys. Jan. Moeyersons. Seppe. Deckers. June 1, 2006. Geoderma. 132. 3. 291–314. ScienceDirect. 10.1016/j.geoderma.2005.04.027.
  20. Contour furrows for in situ soil and water conservation, Tigray, Northern Ethiopia. Tewodros. Gebreegziabher. Jan. Nyssen. Bram. Govaerts. Fekadu. Getnet. Mintesinot. Behailu. Mitiku. Haile. Jozef. Deckers. May 1, 2009. Soil and Tillage Research. 103. 2. 257–264. ScienceDirect. 10.1016/j.still.2008.05.021.

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