Soil in Kilte Awula'ilo

File:Mollic Calcaric Cambisol in Birki Ethiopia profile.jpg

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.{{cite journal |last1= Nyssen|first1= Jan|last2= Tielens|first2= Sander|last3= Gebreyohannes|first3= Tesfamichael|last4= Araya|first4= Tigist|last5= Teka|first5= Kassa|last6= Van De Wauw|first6= Johan|last7= Degeyndt|first7= Karen|last8= Descheemaeker|first8= Katrien|last9= Amare|first9= Kassa|last10= Haile|first10= Mitiku|last11= Zenebe|first11= Amanuel|last12= Munro|first12= Neil|last13= Walraevens|first13= Kristine|last14= Gebrehiwot|first14= Kindeya|last15= Poesen|first15= Jean|last16= Frankl|first16= Amaury|last17= Tsegay|first17= Alemtsehay|last18= Deckers|first18= Jozef|title=Understanding spatial patterns of soils for sustainable agriculture in northern Ethiopia's tropical mountains. |journal=PLOS ONE |date=2019 |volume=14 |issue=10 |pages=e0224041 |doi= 10.1371/journal.pone.0224041|pmid= 31639144|pmc= 6804989|bibcode= 2019PLoSO..1424041N|doi-access= free}}{{cite book |last1= Hunting Technical Services |title= Central Tigre Development Study – Tigre Province Ethiopia, Working Paper I: Soils and land classification. |publisher= Hunting Technical Services Ltd. |location= Hemel Hempstead (U.K.)}}{{cite book |last1=IAO | title= Land evaluation in Kilte Awulaelo - Tigray Region, Ethiopia.|date=2009 | publisher= Ministry of Foreign Affairs, Istituto Agronomico per l'Oltremare |location= Firenze, Italy }}

Factors contributing to soil diversity

= Climate =

Annual rainfall depth is very variable with an average of around 600 mm.{{Cite journal|url=https://doi.org/10.1080/01431161.2013.837230|title=Assessing spatio-temporal rainfall variability in a tropical mountain area (Ethiopia) using NOAA's rainfall estimates|first1=Miro|last1=Jacob|first2=Amaury|last2=Frankl|first3=Mitiku|last3=Haile|first4=Ann|last4=Zwertvaegher|first5=Jan|last5=Nyssen|date=December 10, 2013|journal=International Journal of Remote Sensing|volume=34|issue=23|pages=8319–8335|via=Taylor and Francis+NEJM|doi=10.1080/01431161.2013.837230|hdl=1854/LU-4252226 |s2cid=140560276 |hdl-access=free}} 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.{{Cite book|title=Geo-trekking in Ethiopia's Tropical Mountains|editor-first1=Jan|editor-last1=Nyssen|editor-first2=Miro|editor-last2=Jacob|editor-first3=Amaury|editor-last3=Frankl|date=2019|isbn=978-3-030-04954-6}}

File:Cuesta landscape on the road from Wukro to Hauzien.jpg

= Geology=

The following geological formations are present:

  • Agula Shale{{cite journal |last1=Bosellini |first1=A. |last2=Russo |first2=A. |last3=Fantozzi |first3=P. |last4=Assefa |first4=G. |last5=Tadesse |first5=S. |title=The Mesozoic succession of the Mekelle Outlier (Tigrai Province, Ethiopia). |journal=Mem. Sci. Geol. |date=1997 |volume=49 |pages=95–116}}
  • Antalo Limestone
  • Adigrat Sandstone
  • Enticho Sandstone
  • Edaga Arbi Glacials
  • Precambrian metamorphic rocks
  • Quaternary alluvium and freshwater tufa{{Cite journal|url=https://www.sciencedirect.com/science/article/pii/S0031018205004281|title=Age and backfill/overfill stratigraphy of two tufa dams, Tigray Highlands, Ethiopia: Evidence for Late Pleistocene and Holocene wet conditions|first1=Jan|last1=Moeyersons|first2=Jan|last2=Nyssen|first3=Jean|last3=Poesen|first4=Jozef|last4=Deckers|first5=Mitiku|last5=Haile|date=January 17, 2006|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|volume=230|issue=1|pages=165–181|via=ScienceDirect|doi=10.1016/j.palaeo.2005.07.013}}

= 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.{{cite journal |last1= Nyssen|first1= Jan|last2= Poesen|first2= Jean|last3= Moeyersons|first3= Jan|last4= Deckers|first4= Jozef|last5= Haile|first5= Mitiku|last6= Lang|first6= Andreas|title= Human impact on the environment in the Ethiopian and Eritrean highlands - a state of the art. |journal= Earth-Science Reviews |date=2004 |volume=64 |issue=3–4 |pages=273–320 |doi= 10.1016/S0012-8252(03)00078-3|bibcode= 2004ESRv...64..273N}}{{cite journal |last1=Blond |first1=N. and colleagues |title= Terrasses alluviales et terrasses agricoles. Première approche des comblements sédimentaires et de leurs aménagements agricoles depuis 5000 av. n. è. à Wakarida (Éthiopie). |journal= Géomorphologie: Relief, Processus, Environnement |date=2018 |volume=24 |issue=3 |pages=277–300 |doi=10.4000/geomorphologie.12258 |s2cid=134513245 |url=https://halshs.archives-ouvertes.fr/halshs-02446277/file/BLOND_et_al_Geomorphologie_2018_fac_simile.pdf }} Depending on land use history, locations have been exposed in varying degrees to such land degradation.

Geomorphic regions and soil units

File:CeF2 Wuqro fluval landscape catena.tif

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.{{cite journal |last1=Bui |first1=E.N. |title= Soil survey as a knowledge system. |journal= Geoderma. |date=2004 |volume=120 |issue=1–2 |pages=17–26 |doi=10.1016/j.geoderma.2003.07.006 |bibcode=2004Geode.120...17B }}{{cite journal |title= Principes de la cartographie des pédopaysages dans les Alpes |journal=Écologie |date=1998 |volume=29 |issue=1–2 |pages=49 |id= {{ProQuest|223074690}}}}{{cite book |last1=Tielens | first1=Sander | title= Towards a soil map of the Geba catchment using benchmark soils. MSc thesis.|date=2012 | publisher= K.U.Leuven |location= Leuven, Belgium }} 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 ===

  • Associated soil types
  • shallow, stony, dark, loamy soils on calcaric material (Rendzic Leptosol) (3)
  • moderately deep dark stony clays with good natural fertility (Vertic Cambisol) (10)
  • deep dark cracking clays with very good natural fertility, waterlogged during the wet season (Chromic Vertisol, Pellic Vertisol) (12)
  • Inclusions
  • shallow, stony loam soils with moderate fertility (Eutric Regosol and Cambisol) (21)
  • Brown, silty loams to loamy sands developed on alluvium, with good natural fertility ((Mollic) Fluvisol, Fluvic Cambisol (29)

File: Ch'erkos_church_forest_in_Arebay.jpg

= Incised Giba plateau, upstream of (future) [[Lake Giba]] =

File:CeI1 Incised Giba plateau catena.tif

  • Associated soil types
  • complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • shallow, stony, dark, loamy soils on calcaric material (Rendzic Leptosol) (3)
  • shallow to very shallow, very stony, loamy soils (Skeletic/Leptic Cambisol and Regosol) (4)
  • Inclusions
  • Shallow, stony loam soils with moderate fertility (Eutric Regosol and Cambisol) (21)
  • Deep, dark cracking clays with good fertility, but problems of waterlogging (Chromic and Pellic Vertisol) (12)
  • Brown to dark, silty clay loams to loamy sands developed on alluvium, with good natural fertility (Fluvisol) (30)

= Deeply incised mountainous area (escarpment towards Atsbi) =

File:CeI2 Steep incised mountainous area catena.tif

  • Associated soil types
  • complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • shallow, very stony, silt loamy to loamy soils (Skeletic Cambisol, Leptic Cambisol, Skeletic Regosol) (4)
  • Inclusions
  • stony dark cracking clays with good natural fertility (Vertic Cambisol) (10)
  • shallow, stony loam soils with moderate fertility (Eutric Regosol and Cambisol) (21)

File:Mollic Calcaric Fluvisol along Agula'e River.tif

= Ancient river terraces =

File:Mollic Calcaric Cambisol in Birki Ethiopia.jpg

File:CeB3 Ancient river terraces catena.tif

  • 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
  • complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • shallow to very shallow, very stony, loamy soils (Skeletic/Leptic Cambisol and Regosol) (4)
  • shallow, dark, stony, loamy soils on calcaric material, rich on organic matter (Calcaric Mollic Cambisol) (23)

= Alluvial plains induced by [[tufa]] dams =

File:CeT Tufa dam catena.tif

  • 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
  • shallow, stony, dark, loamy soils on calcaric material (Rendzic Leptosol) (3)
  • shallow, very stony, silt loamy to loamy soils (Skeletic Cambisol, Leptic Cambisol, Skeletic Regosol) (4)

= Incised Agula Shale plateau =

File:CeP2 Incised Agula shale plateau with dolerite catena.tif

  • Associated soil types
  • complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • shallow, very stony, silt loamy to loamy soils (Skeletic Cambisol, Leptic Cambisol, Skeletic Regosol) (4)
  • moderately deep, red-brownish, loamy soils with a good natural fertility (Chromic Luvisol) (20)
  • Inclusions
  • moderately deep dark stony clays with good natural fertility (Vertic Cambisol) (10)
  • deep, dark cracking clays on calcaric material (Calcaric Vertisol, Calcic Vertisol) (11)
  • deep dark cracking clays with very good natural fertility, waterlogged during the wet season (Chromic Vertisol, Pellic Vertisol) (12)
  • shallow, stony loam soils (Eutric Regosol and Cambisol) (21)

= Gently rolling [[Antalo Limestone]] plateau, holding cliffs and valley bottoms =

File:Landscape on the Antalo limestone plateau with a large gully incising Vertisols.jpg and Agula)]]

File:CeUP3 Gently rolling Antalo limestone plateau catena.tif

  • Associated soil types
  • shallow stony soils with a dark surface horizon overlying calcaric material (Calcaric Leptosol) (3)
  • moderately deep dark stony clays with good natural fertility (Vertic Cambisol) (10)
  • deep, dark cracking clays on calcaric material (Calcaric Vertisol, Calcic Vertisol) (11)
  • Inclusions
  • Rock outcrops and very shallow soils (Lithic Leptosol) (1)
  • Shallow very stony loamy soil on limestone (Skeletic Calcaric Cambisol) (5)
  • Deep dark cracking clays with very good natural fertility, waterlogged during the wet season (Chromic Vertisol, Pellic Vertisol) (12)
  • Brown to dark sands and silt loams on alluvium (Vertic Fluvisol, Eutric Fluvisol, Haplic Fluvisol) (30)

= Cuesta landscape =

File:Cuesta landscape on the road from Wukro to Hauzien (2).jpg

File:Cu Cuesta landscape catena.tif

  • Dominant soil type: complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • Associated soil type: shallow, very stony, silt loamy to loamy soils (Skeletic Cambisol, Leptic Cambisol, Skeletic Regosol) (4)
  • Inclusions
  • shallow, stony, dry soils on colluvium (Colluvic Leptosol) (8)
  • shallow to moderately deep, stony, brown loamy soils on calcaric material (Calcic Cambisol and Luvisol) (25)

= Atsaf and Menda’i plains =

File:Abreha and Atsbeha Church 01.jpg

File:SP1 Atsaf plain catena.tif

  • Associated soil types
  • moderately deep, red-brownish, loamy soils with a good natural fertility (Chromic Luvisol) (20)
  • shallow, stony loam soils with moderate fertility (Eutric Regosol and Cambisol) (21)
  • sandy clay loams to sands developed on sandy colluvium (Eutric Arenosol, Regosol, Cambisol) (24)
  • clays of floodplains with very high watertable with moderate to good natural fertility (Eutric Gleysol, Gleyic Cambisol) (33)
  • Inclusions
  • complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • shallow, very stony, silt loamy to loamy soils (Skeletic Cambisol, Leptic Cambisol, Skeletic Regosol) (4)

= Suluh plains with [[metavolcanic]] rocks =

File:SP3 Suluh plain catena.tif

  • Associated soil types
  • complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • moderately deep, red-brownish, loamy soils with a good natural fertility (Chromic Luvisol) (20)
  • shallow, stony loam soils (Eutric Regosol and Cambisol) (21)
  • Inclusions
  • shallow, very stony, silt loamy to loamy soils (Skeletic Cambisol, Leptic Cambisol, Skeletic Regosol) (4)
  • clays of floodplains with very high watertable with moderate to good natural fertility (Eutric Gleysol, Gleyic Cambisol) (33)

= Negash [[geosyncline]] =

File:Wukro-Euphorbe (1).jpg]]

File:SM Negash geosyncline catena.tif

  • Dominant soil type: shallow, stony loam soils (Eutric Regosol and Cambisol) (21)
  • Associated soil types
  • complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • Inclusions
  • moderately deep, brown loamy soils ((Eutric) Luvisol) (26)
  • clays of floodplains with very high watertable with moderate to good natural fertility (Eutric Gleysol, Gleyic Cambisol) (33)

= Circular granite batholith (intrusive) =

File:SI Intrusive granite catena.tif

  • Dominant soil type: shallow, stony loam soils with moderate fertility (Eutric Regosol and Cambisol) (21)
  • Associated soil type: complex of rock outcrops, very stony and very shallow soils ((Lithic) Leptosol) (1)
  • Inclusions
  • shallow, very stony, silt loamy to loamy soils (Skeletic Cambisol, Leptic Cambisol, Skeletic Regosol) (4)
  • clays of floodplains with very high watertable with moderate to good natural fertility (Eutric Gleysol, Gleyic Cambisol) (33)

Soil erosion and conservation

The reduced soil protection by vegetation cover, combined with steep slopes and erosive rainfall has led to excessive soil erosion.{{cite journal |last1=Demel Teketay |title= Deforestation, wood famine, and environmental degradation in Ethiopia's highland ecosystems: urgent need for action. |journal= Northeast African Studies |date=2001 |volume=8 |issue= 1|pages=53–76 |jstor= 41931355|doi= 10.1353/nas.2005.0020|s2cid= 145550500 }}{{cite journal |last1= Nyssen|first1= Jan|last2= Frankl|first2= Amaury|last3= Zenebe|first3= Amanuel|last4= Deckers|first4= Jozef|last5= Poesen|first5= Jean|title= Land management in the northern Ethiopian highlands: local and global perspectives; past, present and future. |journal= Land Degradation & Development |date=2015 |volume=26 |issue=7 |pages=759–794 |doi= 10.1002/ldr.2336|s2cid= 129501591}} 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.{{cite journal |last1= Ayele Almaw|first1= and colleagues|title= 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. |journal= Environmental Management |date=2016 |volume=58 |issue=5 |pages=889–905 |doi= 10.1007/s00267-016-0757-4|pmid= 27605225|bibcode= 2016EnMan..58..889F|s2cid= 4553654}} 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.{{cite journal |last1= Walraevens|first1= K. and colleagues|title= Water balance components for sustainability assessment of groundwater‐dependent agriculture: example of the Mendae Plain (Tigray, Ethiopia). |journal= Land Degradation & Development |date=2015 |volume=26 |issue=7 |pages=725–736 |doi= 10.1002/ldr.2377|s2cid= 140148682}} Measures include the construction of infiltration trenches, stone bunds,{{cite journal |last1= Nyssen|first1= Jan|last2= Poesen|first2= Jean|last3= Gebremichael|first3= Desta|last4= Vancampenhout|first4= Karen|last5= d'Aes|first5= Margo|last6= Yihdego|first6= Gebremedhin|last7= Govers|first7= Gerard|last8= Leirs|first8= Herwig|last9= Moeyersons|first9= Jan|last10= Naudts|first10= Jozef|last11= Haregeweyn|first11= Nigussie|last12= Haile|first12= Mitiku|last13= Deckers|first13= Jozef|title= Interdisciplinary on-site evaluation of stone bunds to control soil erosion on cropland in Northern Ethiopia. |journal= Soil and Tillage Research|date=2007 |volume=94 |issue=1 |pages=151–163 |doi= 10.1016/j.still.2006.07.011|hdl= 1854/LU-378900|url= https://biblio.ugent.be/publication/378900|hdl-access= free}} check dams,{{cite journal |last1= Nyssen|first1= J.|last2= Veyret-Picot|first2= M.|last3= Poesen|first3= J.|last4= Moeyersons|first4= J.|last5= Haile|first5= Mitiku|last6= Deckers|first6= J.|last7= Govers|first7= G.|title= The effectiveness of loose rock check dams for gully control in Tigray, Northern Ethiopia. |journal= Soil Use and Management |date=2004 |volume=20 |pages=55–64 |doi= 10.1111/j.1475-2743.2004.tb00337.x|s2cid= 98547102}} small reservoirs such as La'ilay Wuqro and May Azaboy as well as a major biological measure: exclosures in order to allow forest regeneration.{{Cite journal|url=https://www.sciencedirect.com/science/article/pii/S0016706105001576|title=Sediment deposition and pedogenesis in exclosures in the Tigray highlands, Ethiopia|first1=Katrien|last1=Descheemaeker|first2=Jan|last2=Nyssen|first3=Joni|last3=Rossi|first4=Jean|last4=Poesen|first5=Mitiku|last5=Haile|first6=Dirk|last6=Raes|first7=Bart|last7=Muys|first8=Jan|last8=Moeyersons|first9=Seppe|last9=Deckers|date=June 1, 2006|journal=Geoderma|volume=132|issue=3|pages=291–314|via=ScienceDirect|doi=10.1016/j.geoderma.2005.04.027}} 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.{{Cite journal|url=https://www.sciencedirect.com/science/article/pii/S0167198708001268|title=Contour furrows for in situ soil and water conservation, Tigray, Northern Ethiopia|first1=Tewodros|last1=Gebreegziabher|first2=Jan|last2=Nyssen|first3=Bram|last3=Govaerts|first4=Fekadu|last4=Getnet|first5=Mintesinot|last5=Behailu|first6=Mitiku|last6=Haile|first7=Jozef|last7=Deckers|date=May 1, 2009|journal=Soil and Tillage Research|volume=103|issue=2|pages=257–264|via=ScienceDirect|doi=10.1016/j.still.2008.05.021}}

References