Soil Conservation Research Programme (SCRP) Area of Dizi, Illubabor, Ethiopia: Long-term Monitoring of the Agricultural Environment 1988 - 1994 Soil Erosion and Conservation Database 2000 Centre for Development and Environment,University of Berne, Switzerland, in Association with The Ministry of Agriculture, Ethiopia II TheSoilConservationResearchProgrammewasfundedbytheSwiss Agency for Development and Cooperation (SDC) and the Government of Ethiopia.TheimplementingagencywastheEthiopianMinistryof Agriculture. The executingagency wastheCentre forDevelopmentand Environment, Institute of Geography, University of Berne, Switzerland. CoverView of the Dizi catchment, looking towards the east-northeast, based on an orthophoto (1967) and a digital terrain model derived from successive airphoto. View Properties Observers position (UTM 37): E: 783,870; N: 928,120 Observers altitude: 3100 m asl Azimuth: 82 Copyright 2000Soil Conservation Research Programme, Centre for Development and Environment Addresses of the programmeSoil Conservation Research Programme Ministry of Agriculture P.O. Box 2597 ADDIS ABEBA Ethiopia of the executing agencyCentre for Development and Environment Institute of Geography University of Berne Hallerstrasse 12 3012 BERNE Switzerland E-Mail: cde@giub.unibe.ch http://www.cde.unibe.ch Language editingAnne B. Zimmermann LayoutUlla Schpbach, Brigitta Stillhardt Printed byLang Druck AG, Liebefeld (Switzerland) IIIPreface IncreasinglyalarmedbytheseriousnessoflanddegradationinEthiopiaand encouragedbyeffortsundertakenbyEthiopiangovernmentstoconservesoils andwaterforagriculturalpurposes,scientistsanddevelopmentspecialists createdtheSoilConservationResearchProgramme(SCRP)in1981.Theiraim was to contribute to the technical, ecological, economic and social improvement of governmental efforts. The SCRP was carried out with the support of the Swiss AgencyforDevelopmentandCooperation(SDC)inaseriesofprogramme phasesthatlastedfrom1981to1998.Since1998,regionalSCRPofficeshave continued their own research at the original SCRP sites. ThepresentdocumentpresentsthemaindatacollectedatoneoftheSCRP researchsites:DiziResearchStation,situatedinIllubabor,Ethiopia.Itis limited to data obtained by the core SCRP programme. In addition, a number of supplementary studies were carried out at most research sites by MSc and PhDstudents,aswellasbyconsultantsandexperts.Theresultsoftheir studies have been published elsewhere. The present document is thus not the sole output of SCRP research in Dizi. But it can constitute an extremely useful source of information for further analysis, synthesis, and interpretation in view ofdevelopmentrecommendationsandtechnicalproposals;itmayalso stimulate further research. DiziResearchStationwasestablishedinApril1988asthesixthSCRP researchsiteinEthiopia.SituatedintheIllubaborHighlandsinWestern Ethiopia, the catchment lies at a favourable altitude for agricultural purposes, though the elevation is rather low and the climate hot and moist. Much of the catchmentisstillcoveredbyforests,althoughmassiveresettlementof communitiesfromTigrayandWelloin1985ledtothecreationofseveral new villages in the catchment. These had been established at the beginning of the research programme but were abandoned again to a large extent before theendoftheprogramme.Soilconservationwasnotintroducedinthe catchment.Thelocalcommunitiestraditionallyuseanalternatingsystemof fallowandcultivation,withmaizeasabasiccropproducinggoodground coverandthusreducingtheriskoferosion.Problemsofsoilfertilityexistin Dizi because of soil genesis and soil degradation. Methodologically, the present database report isthe result of a long chain of activities.Theseactivitiesstartedwhentheagriculturalsitewasselectedby theSCRPtobearesearchcatchment,andafterapermanentstationwas establishedandresidentstaffappointed.Amodestinfrastructurewassetup fordatacollection,e.g.fieldplotsforvariouspurposessuchasrunoffand erosion monitoring, soil conservation experimentation, monitoring of land use IV and production, soil surveys, and appraisals of land degradation. Furthermore, staff were employed for data collection, i.e. research assistants who collected suchdataasriversedimentsamplesevery10minutesduringallrainfall events, day and night, season after season and year after year. Data were then submittedtofurtherprocessing,eitheratthestation(e.g.landuseand harvest monitoring data), or after the samples had been transported to SCRP headquartersinAddisAbeba(e.g.sedimentsamples).There,laboratory analyseswereconducted,datawerecompiledandencoded,mapswere digitised.Thenthedatawereanalysedandincludedinadetaileddatabase. Thepresentsummaryreportisoneofmanypossibleproductsdrawnfrom this database in a final joint effort involvingSCRPstaff in Addis Abeba and at CDE in Berne. Mostimportant,however,istheinterpretationofthesedata.Initialworkin this regard was done by specialists from SCRP; the results were presented to externalspecialistssuchassoilconservationexperts,agriculturalstaffand extensionists,andfurtherstakeholderssuchaspolicy-makers,school teachers,orschoolchildren.Internationalconsultants,donors,evaluation teams, and researchers working in similar problem settings and environments were also informed. Asmentionedabove,SCRPhasproducedanumberofadditionaloutputs apart from the database. Over 45 Research Reports, regular Progress Reports for the first 8 years, immediate recommendations at least once every year, as wellastrainingmanuals,trainingcourses,schoolbooks,mapsandGIS analyses,andextrapolationsoftheresultstowiderareashavebeenissued. These outputs are listed in the present document. They can be obtained from theNaturalResourcesDevelopmentandRegulatoryDepartmentinAddis AbebaorfromtheBureauxofAgricultureintheOromia,Amhara,and Southern Peoples Region, as well as from CDE at the University of Berne. I would like to thank every individual who contributed to the huge task of building up a national research network in soil and water conservation either directly or indirectly, over a short or long period, at the field stations or the regional offices, in Addis Abeba or outside Ethiopia. Principal SCRP staff are listed in Annex 1. Personally, as the initiator and first director of the SCRP from 1981 to 1987 and thepersonresponsiblefortheprogrammeatCDEthereafter,Iamdeeply indebtedtoallthosewhoenthusiasticallyworkedforSCRP,dedicatedamajor part of their professional lives to the programme, and thus provided considerable support towards Ethiopia's national effort to combat land degradation. If a name isnotlistedinAnnex1,thisdoesnotmeanthatanindividualsinputhasbeen neglected; I apologise for any omissions which may have occurred. Berne, June 2000Hans Hurni VTable of Contents Illustrations ............................................................................................................. VI Tables ..................................................................................................................... VII Abbreviations........................................................................................................ VIII Station Overview .................................................................................................... 1 Soils........................................................................................................................... 3 Soil Classification.................................................................................................... 3 Climate ..................................................................................................................... 7 Rainfall ................................................................................................................... 8 Temperature ....................................................................................................... 13 Wind.................................................................................................................... 16 Evaporation ......................................................................................................... 19 Land Use and Crop Production........................................................................... 21 Land Use Patterns in the Catchment ................................................................... 21 Crop Cover ......................................................................................................... 23 Crop Yield and Biomass Production .................................................................... 23 Soil Erosion and Soil and Water Conservation.................................................. 27 Test Plot Results .................................................................................................. 28 Micro-plot Results................................................................................................ 33 Soil Conservation Experiments on Experimental Plots and Farmers Fields ......... 35 Results of Hydrometric Measurements on the Catchment .................................. 41 Social and Economic Characteristics .................................................................. 45 Collection of Social and Economic Data............................................................... 46 Demographic Features ........................................................................................ 47 Livestock Holdings............................................................................................... 50 Landholdings........................................................................................................ 52 Bibliography........................................................................................................... 55 Progress Reports ................................................................................................. 55 Research Reports................................................................................................. 55 African Studies Series........................................................................................... 59 Manuals................................................................................................................ 59 Other Publications and Papers............................................................................. 59 Thesis .................................................................................................................. 62 Maps.................................................................................................................... 65 Annex 1 .................................................................................................................. 67 Annex 2 .................................................................................................................. 69 VI Illustrations Figure 1:Climate diagram for Dizi......................................................................................... 8 Figure 2:Mean monthly rainfall and air temperature ............................................................ 9 Figure 3:Relation between intensity and duration of rainfall ............................................... 10 Figure 4:Mean monthly erosivity and rainfall ......................................................................... 10 Figure 5:Direction of rainfall ............................................................................................... 11 Figure 6:Mean daily air temperatures ................................................................................. 13 Figure 7:Mean daily soil surface temperatures ................................................................... 15 Figure 8:Wind direction and frequency at 8 a.m. and at 6 p.m........................................... 16 Figure 9:Evaporation measured by Piche tube evaporimeter............................................. 19 Figure 10:Land use in % of total catchment area in 1989 and 1995..................................... 22 Figure 11:Soil cover curves for selected crops ..................................................................... 23 Figure 12:Annual rainfall, erosivity, runoff, and soil loss on test plots................................... 29 Figure 13:Mean monthly rainfall, erosivity, runoff, and soil loss on test plots....................... 31 Figure 14:Mean monthly rainfall, erosivity, runoff, and soil loss on micro-plots.................. 34 Figure 15:Absolute and relative annual runoff and soil loss on experimental plots............... 37 Figure 16:Absolute and relative annual crop yield and biomass production on experimental plots........................................................................................... 38 Figure 17:Annual rainfall, catchment discharge, and suspended sediment yield................... 42 Figure 18:Mean monthly catchment discharge and suspended sediment yield..................... 42 Figure 19:Size of families in the research area in Dizi and Gey............................................. 47 Figure 20:Age and gender structure of the sample population in Dizi and Gey........................ 49 Figure 21:Distribution of inhabitants in Dizi and Gey (Metu area) according to language and religion............................................................................................. 49 Figure 22:Data on livestock structure for selected households in the research area.......... 50 Figure 23:Data on oxen holdings for selected households in the research area................... 51 Figure 24:Data on landholdings for selected households in the research area.................... 53 VIITables Table 1:Erodibility classes ....................................................................................................4 Table 2:Erosion status and history of soil development.......................................................5 Table 3:Soil productivity and soil fertility.............................................................................5 Table 4:Climate: type of data collected, duration of collection, and technique of measurement...............................................................................7 Table 5:Monthly and annual frequency of rainfall events according to the direction of rainfall ................................................................................................11 Table 6:Monthly and annual air temperatures ...................................................................14 Table 7:Monthly and annual soil surface temperatures......................................................15 Table 8:Monthly and annual frequency of winds according to wind direction at 8 a.m. ....17 Table 9:Monthly and annual frequency of winds according to wind direction at 6 p.m.....18 Table 10:Mean daily evaporation per month .......................................................................20 Table 11:Land use and crop production: type of data collected, duration of collection, and technique of measurement.............................................................................21 Table 12:Land use in % of total catchment area in 1989 and 1995.....................................22 Table 13:Mean annual net yield per crop.............................................................................24 Table 14:Soil erosion and conservation: type of data collected, duration of collection, and technique of measurement.............................................................................28 Table 15:Annual rainfall, erosivity, runoff, and soil loss on test plots...................................30 Table 16:Mean monthly rainfall, erosivity, runoff, and soil loss on test plots .......................32 Table 17:Mean annual runoff and soil loss on test plots and comparable micro-plots.........33 Table 18:Annual rainfall, erosivity, runoff, and soil loss on micro-plots..............................33 Table 19:Mean monthly rainfall, erosivity, runoff, and soil loss on micro-plots ...................35 Table 20:Absolute and relative annual runoff and soil loss on experimental plots ...............36 Table 21:Absolute and relative annual crop yield and biomass production on experimental plots ...........................................................................................39 Table 22:Monthly and annual catchment discharge .............................................................41 Table 23:Monthly and annual suspended sediment yield.....................................................43 Table 24:Size of families per household...............................................................................47 Table 25:Age and gender structure of the sample population in Dizi and Gey....................49 Table 26:Distribution of inhabitants in Dizi and Gey (Metu area) according to language and religion........................................................................49 Table 27:Data on livestock structure...................................................................................51 Table 28:Data on oxen holdings ..........................................................................................52 Table 29:Data on landholdings.............................................................................................53 VIII Abbreviations Crops:co = coffee fl = fallow gr = grass mz = maizesg = sorghum te = tef Cs:Sediment concentration [g/l] CV %:CV x 100 CV:Coefficient of variation SDMean EP:Experimental plot; 6 x 30 m Eros:Erosivity [J/mh] HH:Household Max:Maximum Mean Dev:Mean Deviation x xniin=1 Mean:Arithmetic mean nxnii =1 Min:Minimum MOA:Ministry of Agriculture MP:Micro plot; 1 x 3 m N:Number of samples No sel. HH:Number of selected households PA:Peasant association Prec:Precipitation [mm] Q:Discharge [l/s] Qs:Sediment rate [t] Qv:Discharge volume [m3] Rel Dev:Relative Deviation MeanMeanDev IXRuof:Runoff [mm] SCRP:Soil Conservation Research Programme SD:Standard Deviation ( ) x xniin=21 Solo:Soil loss [t/ha] TP:Test plot; 2 x 15 m xx:Abbreviation of station name Aj = Anjeni At = Andit Tid Di = Dizi Gu = Gununo Hu = Hunde Lafto Ma = Maybar yy:Abbreviation of year Viewofalandscapesequenceneartestplot1inDizi,withswampyareainthe foreground, followed by grassland and cultivation, banana, and natural trees on the hilltop. Source: H. Hurni, 12. July 1988 Station Overview 1Station Overview Location:3536E / 822N. Region: Illubabor; 5 km north of Metu Altitudinal range:1565 - 1789 m asl Catchment size:Hydrological catchment: 672.7 ha; Topographical catchment: 669.3 ha Climate:According to Thornthwaite: humid Mean annual temperature: 21 C Mean annual rainfall: 1512 mm Length of growing period: 245 days Geology:Precambrian Gneiss Soils:Mainly Lixisols, few Fluvisols and Cambisols Soil degradation status:Low to medium degradation. Soil fertility restricted by phosphorus deficiency Agro-ecological classification:Wet Weyna Dega Farming system:Rainfed, subsistence-oriented farming system with ox-ploughing. Coffee as cash crop. Uncontrolled grazing practice Main crops:Maize, tef, sorghum. Coffee as cash crop Climax vegetation:Broadleaf Baphia forest. Evergreen rain forest Population density (PA):80 inhabitants per km2 in 1990 Mean size of landholdings (PA):1990: 2.6 ha per household Livestock holdings (PA):1991: Mean total herd size per family: 5.6 animals, thereof 1.4 oxen Station established in: May 1988 The Agricultural Environment of Dizi, Illubabor, Ethiopia 2Soils 3Soils SomeoftheparticularitiesoflargerelevantstretchesofsoilinDizi cannotbeclassifiedaccordingtothesoilunitslistedintheFAO-UNESCO, Revised Legend of the Soil Map of the World (1974/1988). ThereforesoilsinDiziareclassifiedaccordingtotheunitwhich correspondsbesttomostoftheobservedandanalysedpedological features-inthepresentcaseasLixisols.FourmajorLixisolsoilunits can be distinguished in the Dizi catchment. Soil Classification The basis for soil classification is the FAO-Unesco, Revised Legend of the Soil Map of the World (1974/1988). ThereisapredominanceofhaplicLixisolsdevelopedinsituona weatheredRegolithlayer.Thesesoilsarecharacterisedbyadense layerofgravelundertheorganictopsoil.Suchstonelinesactasa barrierforrootability.Thesoilsareverydeep,medium-texturedand well drained. The layer of gravel occurs at variable depth and may thus limitfavourablephysicalconditions.Furtherlimitationsforcrop productionareaverylowcontentinavailablephosphorusandoften alsoinnitrogen.Moreover,organicmattercontentsdecreaserapidly undercultivationbeingashighas15%innewlydeforestedlandand below2%after10-15yearsofcultivation.Inrelationtotheeffective cationexchangecapacity,thesesoilshaveahighbasesaturation.As most nutrients and the organic matter are concentrated in the topsoil, and the rooting volume is restricted, soil erosion severely threatens the fertility of these soils. BesideshaplicLixisols,albicandgleyicLixisolsoccurinthesamesoil unit,butonlyinsmallareasofthecatchment.Theirmajor morphologicalfeatures,chemicalproperties,andlimitationsresemble those of the above-mentioned haplic Lixisols. The second type of soil unit consists of fluvi-haplic Lixisols. These soils developed on colluvial deposits along the margins of valley floors: their profilesareverydeep.Thesoilshavefavourablephysicalproperties The Agricultural Environment of Dizi, Illubabor, Ethiopia 4andoffernolimitationstorooting.Theirchemicalconditionsare similartothoseofthehaplicLixisols.Nutrientsandorganicmatter, however, are more homogeneously distributed throughout the profile. Themajorconstraintsforcropproductionaretheverylow phosphoruscontentsaswellasavailablenitrogencontentsthatare often low. As the soils are often rejuvenated by deposit material, other nutrients are provided in satisfactory quantities. Theflatvalleyfloorsarecoveredbygleyic-umbricFluvisols.Seasonal flooding lasting about 6 months per year reduces the growing period to about5 monthsperyear.Alluvialdepositsrejuvenatethesemedium-textured,poorlydrainedsoilseveryyear.Thus,withregardto chemicalconditions,theyareratherfertile.Onlytheavailabilityof nitrogen is low, owing to reduced biological activity. The fourth soil unit consists of lepti-umbric Cambisols. Theirextent is limitedinthecatchmentareaandtheyareofminorimportancefor farming activities. These soils developed on bedrock and are shallow to moderatelydeep,withcontinuoushardrockatthebottom;their topsoil has a high organic matter content. Table 1:Erodibility classes, Dizi Soil typeErodibility classes Haplic Lixisols3 Fluvi-haplic Lixisols3 Gleyic-umbric Fluvisols4 Lepti-umbric Cambisols3 Table 1 lists the soil units, associated with erodibility classes, according toFAOclassification.1isequivalenttoverylowerosivity,6tovery higherosivity.NomeasurementsweremadeinDizi;thevaluesare estimates from known values for the same soil types in other Ethiopian highland areas. Soils 5Table 2:Erosion status and history of soil development in Dizi Soil typeErosion status Haplic LixisolsSeverely affected by soil erosion Fluvi-haplic LixisolsModerately affected by soil erosion; partly accumulation resulting from seasonal flooding Gleyic-umbric FluvisolsMostly accumulation due to flooding lasting about 6 months Lepti-umbric CambisolsModerately affected by soil erosion Table 3:Soil productivity and soil fertility in Dizi Soil typeProductivity / Fertility Haplic LixisolsSoil fertility concentrated in top layer; restricted by very low available phosphorus and nitrogen contents Fluvi-haplic LixisolsSoil fertility restricted by very low available phosphorus and nitrogen contents Gleyic-umbric FluvisolsRather fertile soils, productivity restricted by seasonal flooding Lepti-umbric CambisolsSoil fertility restricted by shallowness; nutrients concentrated in topsoil layer Note:The precondition for the above classification is sufficient soil depth Further reading Research Reports Hagmann, J. 1991 / Kefeni Kejela. 1996 African Studies Series Solomon Abate. 1994 Other Publications and Papers Hurni, H. 1983a, 1983b, 1988a, 1990 Maps Hagmann, J. 1991 The Agricultural Environment of Dizi, Illubabor, Ethiopia 6Climate 7Climate Table 4showstheclimaticdatacollectedinDiziinrelationto monitoring of soil erosion and conservation process: Table 4:Climate in Dizi: type of data collected, duration of collection, and technique of measurement ParameterDevice / methodAvailability in database* Data source file (primary database)** Resolution and frequency of data collection Amount and intensity of rainfall Pluviometer/Pluvio-graph (monthly chartrolls) 01/06/1988 -31/12/1994 diyyplre.dbf***Segments of similar rainfall intensities ErosivityCalculation on the basis of rainfall intensitiy and duration 01/06/1988 -31/12/1993 diyy_a03.dbf (secondary database) Per storm Direction of rainfall and inclinationInclinometer****01/08/1988 -31/12/1993 diyyinri.dbfDaily Air temperature (min. and max.) Thermometer, 1.5 m above ground 03/08/1988 -31/12/1994 diyycscd.dbfAt 8 a.m. and 6 p.m. Soil surface temperature (min. and max.) Thermometer, 0.1 m above soil surface 03/08/1988 -31/12/1994 diyycscd.dbfAt 8 a.m. and 6 p.m. EvaporationPiche tube evaporimeter 03/08/1988 -31/12/1994 diyycscd.dbf At 8 a.m. and 6 p.m. EvaporationClass-A-Pan02/03/1993 -31/12/1994 diyycscd.dbfAt 8 a.m. and 6 p.m. Wind direction and strength Observation03/08/1988 -31/12/1994 diyycscd.dbfAt 8 a.m. and 6 p.m. Notes:*Due to political and institutional problems, not all data collected are available in a digital format. **In the file names, the letters di stand for the station name (Dizi), yy for the year, and the other four letters identify the content of the respective file (e.g. filename di87cscd.dbf = Dizi / 1987 / climatic station climatic data) ***This file contains records of the amount for each interval of constant intensity within the same rainfall event. For further analysis these amounts are summarised as storm values. Definition of a storm: the minimum amount of rainfall must be 12.5 mm, and one event must be separated from the next or previous one by at least 6 hours. ****Developed by H. Hurni (1981), published 1989b. DiziislocatedintheWetWeynaDegaagro-climaticzone.Figure 1 showsthestandardisedclimaticpatternforDizi(accordingtoWalter, 1964):aunimodalrainfallregimewith7 monthsofrainfallexceeding 100 mm.ConditionsduringthemonthsfromNovembertoFebruary are arid; the de Martonne and Lauer index of aridity (1952; see SCRP: The Agricultural Environment of Dizi, Illubabor, Ethiopia 8Concept and Methodology) for these four months is below 20. In the Walter diagram, the rainfall graph drops below the temperature graph. Figure 1:Climate diagram for Dizi Rainfall Amount of Rainfall ThegeneralrainfallpatternisshowninFigure 2.Dailyqualitativeand quantitativemeasurementsfortheperiodfrom1988to1994are grouped by months and averaged out. mean rainfall events per year: on 176 days minimum rainfall events per year: on 162 days maximum rainfall events per year: on 193 days meanstormeventsperyear:on42 days(forthedefinitionofa storm, see notes, Table 4) minimum storm events per year: on 36 days maximum storm events per year: on 51 days mean rainfall amount per year: 1512 mm minimum rainfall amount per year: 1302 mm maximum rainfall amount per year: 1665 mm mean minimum rainfall amount per month: 14 mm (January) mean maximum rainfall amount per month: 311 mm (August) maximumrainfallamountinasingleevent:81.9 mm(in1988,the amount equalled 23 % of the monthly total of 361.7 mm) Climate 9 Figure 2:Mean monthly rainfall (June 1988 - 1994) and air temperature (1989 - 1994) in Dizi Intensity and Erosivity of RainfallBoth the duration and the amount of rainfall provide information about the intensity of the event (mm/h). Figure 3 shows the relation between rainfallintensityanddurationoftherainfallevent.Themaximum durationinthegraphislimitedto300 minutes(5hours).Rainfallhad greatest intensity during storms of short rainfall duration, while rainfall events with lowest intensity were usually of long duration. Rainfallerosivity(J/mh)iscalculatedonthebasisofWischmeierand Smith (1965). One intense single rainfall event can cause up to 33 % of monthlysoilloss,aswasthecaseon19thAugust1991,with49.2 mm of rainfall and an erosivity of 105.14 J/mh. Figure 3:Relationbetweenintensityanddurationofrainfall (August 1988 1994, Dizi) 05101520253035Temperature [C]050100150200250300350400450Rainfall [mm]Rainfall [mm] 14 19 62 108 184 197 239 311 249 139 24 29Average monthly minimum air temperature 10.1 10.9 12.7 14.0 14.6 14.6 14.6 14.6 14.2 12.9 11.3 10.4Average monthly maximum air temperature 30.4 31.6 32.4 30.8 29.0 27.4 25.9 26.0 27.4 28.1 29.1 29.8Average monthly air temperature 20.2 21.2 22.5 22.4 21.8 21.0 20.3 20.3 20.8 20.5 20.2 20.1Jan Feb March April May June July Aug Sept Oct Nov DecThe Agricultural Environment of Dizi, Illubabor, Ethiopia 10Figure 4 represents the mean monthly erosivity and rainfall in the years 1988 - 1994.In Dizi, erosivity is bimodal, the rainfall regime unimodal. A first peak of erosivity usually occurs during May, the second peakin August and September. Figure 4:Mean monthly erosivity (June 1988 - 1993) and rainfall (June 1988 - 1994), Dizi Direction of Rainfall The direction of rainfall is recorded for the period from 1988 to 1993. Figure 5andTable 5showtheresultsofthemeasurements.The dominantdirectionofrainfallisthesameasthewinddirectioninthe morning:north-easttoeast.Thestatisticsshowthatthereareabout the same number of rainfall events in the mornings as there are in the afternoons (50.5 % versus 49.5 %). Figure 5:DirectionofrainfallinDizi(1988 - 1993).Thefrequencyofrainfallevents usedintheanalysisisindicatedontheverticalaxis 050100150200250300350400450Erosivity [J/mh]050100150200250300Rainfall [mm]Rainfall [mm] 14 19 62 108 184 197 239 311 249 139 24 29Mean monthly erosivity 0 7 19 51 82 67 102 166 132 61 0 14Mean plus one standard deviation 0 20 46 94 162 107 122 274 200 87 0 44Mean minus one standard deviation 0 -7 -9 8 3 27 82 57 63 35 0 -16Jan Feb Mar Apr May June July Aug Sep Oct NovDecClimate 11Table 5:Monthlyandannualfrequencyofrainfalleventsaccordingtothedirectionof rainfall (1989 1993, Dizi)Year Month N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW Total 1989January February1111116 March22213111114 April11131119 May2123321121321 June25313222121 July3112311212314227 August22246131112126 September3555133227 October1411311113 November11125 December112221110 1989 Total1511916222511619434113911179 Table 5 (cont.) Year Month N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW Total 1990January213 February1113 March1113 April12216 May23421111116 June21124411631127 July121111171211121 August21243102226 September145321811329 October111211111111 November121116 December123 1990 Total6314141710108407852262154 1991January111115 February11114 March132212111115 April134311114 May333111111217 June1235111418 July1122511512122 August1343432121 September3122111221117 October111313212 November11114 December112 1991 Total9614222610108167349241151 1992January3115 February112 March41117 April1541213 May14811111119 June771112221 July2234112123122 August212114341221 The Agricultural Environment of Dizi, Illubabor, Ethiopia 12September1352132321124 October311113131217 November13111310 December11114 1992 Total2817382035410313916755165 1993January112 February1111116 March2122119 April1231211112 May311511121218 June11341111411221 July22153121131224 August1427111112223 September119812221128 October554121624 November22116 December 1993 Total14112838152526371395105173 Temperature Air Temperature Air temperature was measured 1.5 m above ground on a daily basis for theperiodfromAugust1988toDecember1994.Figure 6shows averagedataforaone-yeartimeline:mean,minimumandmaximum dailyairtemperature(n = 2191).Extrememeasurementsduringthe recorded period were: range of daily minimum air temperature: 2 C (measured twice) to 25 C (measured once) range of daily maximum air temperature: 9 C (measured once); to 37 C (measured twice) mean daily minimum air temperature: 12.9 C mean daily maximum air temperature: 29.0 C Figure 6:Meandailyairtemperatures,andmeandailyminimumandmaximumair temperatures (August 1988 1994, Dizi) Climate 13Table 6liststhemonthlyandannualairtemperatures.Themonthly temperaturesrangedfrom20.1 CinDecemberto22.5 CinMarch. The difference between the coldest and the hottest month was 2.4 C. In99 %ofallrecordedcasesthedailytemperaturefluctuationswere higher than 2.4 C. The Agricultural Environment of Dizi, Illubabor, Ethiopia 14Table 6:Monthly and annual air temperatures (1989 1994, Dizi) Monthly minimum Monthly maximum Monthly mean YearAnnual mean January10.130.420.2198921.0 February10.931.621.2199020.6 March12.732.422.5199120.8 April14.030.822.4199221.0 May14.629.021.8199321.1 June14.627.421.0199421.1 July14.625.920.3 August14.626.020.3 September14.227.420.8 October12.928.120.5 November11.329.120.2 December10.429.820.1 Soil Surface Temperature DuringtheperiodfromAugust1988toDecember1994soilsurface temperaturewasmeasuredonadailybasisat0.10 maboveground. Figure 7 shows the average data for a one year timespan (n = 2112). Inmorethan96 %ofrecordedcasesmeandailysoilsurface temperature was higher than mean daily air temperature. The contrast betweentemperaturesintheairandonthesoilsurfacewasgreater duringthedryseasonthanduringtherainyseason.Inabout90 %of cases,measurementsrevealedagreaterdailytemperaturerangeon the surface of the soil than in the air. Soil surface temperature is more sensitive to seasonal variations of the weather than air temperature. Heat insulation and radiation of the soil body is most intense in the dry season after the rain. At this time of the year, maximum soil surface temperatures are higher than maximum air temperatures,butminimumsoilsurfacetemperaturesarenearlythe same as minimum air temperatures. Climate 15 Figure 7:Mean daily soil surface temperatures, and mean daily minimum and maximum soil temperatures (August 1988 1994, Dizi) Extreme measurements during the recorded period were: rangeofdailyminimumsoilsurfacetemperature:4 C(measured once) to 22 C (measured three times) range of daily maximum soil surface temperature: 20 C (measured once), to 45 C (measured five times) mean daily minimum soil surface temperature: 13.9 C mean daily maximum soil surface temperature: 31.8 C Table 7:Monthly and annual soil surface temperatures (1989 1994, Dizi) Monthly minimum Monthly maximum Monthly mean Annual mean January10.5433.9522.24198922.19 February11.4836.1823.83199022.81 March13.0537.2825.17199122.49 April14.4834.5524.51199222.71 May15.5131.5723.54199323.18 June15.8929.1822.54199423.74 July15.8327.5221.67 August15.8427.4021.62 September15.8829.3622.62 October14.5730.3522.46 November12.9231.5622.24 December11.6933.1922.40 Wind Winddirectionwasobservedtwiceaday(8 a.m.and6 p.m.)during theperiodfromAugust1988toDecember1994withathread attached to a post. Wind strength is only roughly described by the four classes: none / weak / medium / strong wind. As shown in Figure 8 and The Agricultural Environment of Dizi, Illubabor, Ethiopia 16Tables 8and9,themostfrequentwinddirectioninthemorningis from the east, and from the west in the evening. Figure 8:Wind direction and frequency at 8 a.m. (top) and at 6 p.m. (bottom) (August 1988 1994, Dizi). The frequency of directions is given on the vertical axis. Wind direction8 a.m.01 0 02 0 03 0 0NNEESESSWWNWWind direction6 p.m.0100200300NNEESESSWWNWClimate 17Table 8:Monthly and annual frequency of winds according to wind direction at 8 a.m. (1989 1994, Dizi) Table 9:Monthly and annual frequency of winds according to wind direction at 6 p.m. (1989 1994, Dizi) Evaporation EvaporationinDiziwasmeasuredbyaPichetubeevaporimeterfrom August 1988 to December 1994, and by a class-A-Pan from 2nd March 1993untiltheendof1994.Class-A-Pandataarenotpresented becauseoftheshortperiodofdatacollection.Thetwodifferent measurementsystemsarenotreallycomparable:itseemsthatthe class-A-Panreactsfastertochangesinweatherconditionsthanthe tube evaporimeter. Figure 9showstheaveragedailyevaporationvaluesforaone-year timespanwithaconfidenceintervalofonestandarddeviation.The highestmeanmonthlyevaporationvaluemeasuredbyPichetube evaporimeteroccurredduringthedryseasoninMarch,whichisalso thewarmestmonth.Table 10liststhemonthlyevaporation measurements for the period from August 1988 to December 1994. The Agricultural Environment of Dizi, Illubabor, Ethiopia 18 Figure 9:EvaporationmeasuredbyPichetubeevaporimeter(August1988 - 1994, Dizi). The daily 24-hour period started at 8 a.m. 0246810121416182001. 0110. 0221. 0330. 0409. 0619. 0728. 0807. 1016. 1126. 12Date lineEvaporation per 24 hours [ml]Mean(+Standard deviation)(-Standard deviation)Climate 19Table 10:Mean daily evaporation [mm] per month (1989 - 1994) 198919901991199219931994 January4.93.57.93.74.23.9 February5.54.19.63.84.75.0 March5.05.310.04.34.75.5 April4.65.510.03.23.24.2 May3.63.06.62.32.42.1 June2.81.94.61.51.51.7 July2.51.53.81.31.31.2 August2.01.43.30.91.31.3 September2.31.63.82.11.41.8 October2.32.34.31.91.93.3 November2.62.55.12.82.52.9 December2.54.36.63.13.23.9 Further reading Research Reports Krauer, J. 1988 Papers Hurni, H. 1989b Thesis Haileselassie Berhanu. 1989 The Agricultural Environment of Dizi, Illubabor, Ethiopia 20Land Use and Crop Production TheDiziresearchunitisarepresentativestationfortheWetWeyna Degaclimaticbelt.Table 11liststheparametersrecordedforcrop, crop yield and biomass and indicates the respective data source files. Table 11:LanduseandcropproductioninDizi:typeofdatacollected,durationof collection, and technique of measurement ParameterDevice / method Availability in database* Data source file (primary database)** Resolution / frequency of data collection Crop type and crop cover in % Weekly observation at different locations 18.09/1988 - 31/12/1993 Data missing from 25/10/1991 to 30/04/1993 diyycavc.dbfWeekly Yield (grain, straw, biomass) Analysis of different locations, test plots and experimental plots 26/10/1988 - 31/12/1994. Data missing from 10/11/1991 to 16/10/1992 diyycaha.dbf***Seasonally, during harvest Sowing date, ploughing date, use of fertiliser, crops during the last two periods Observations and interviews 26/10/1988 - 31/12/1994. Data missing from 10/11/1991 to 16/10/1992 diyycaha.dbfWeekly / seasonally Notes:*Due to political and institutional problems, not all data collected are available in a digital format. **In the file names, the letters di stand for the station name (Dizi), yy for year, and the other four letters identify the content of the respective file (e.g. filename di87caha.dbf = Dizi / 1987 / catchment harvest) ***Micro-plot data is available only from 1989 to 1990 Land Use Patterns in the Catchment ThetotalsizeoftheDizicatchmentis672.7 ha.Theunimodalrainfall regime in Dizi does not allow two cropping seasons. The predominant annualcropismaize,partlyfollowedbytefandsorghuminthenext rainyseason.Over90 %ofarablelandiscoveredwithmaize.The secondimportantcropinDiziiscoffee,mainlycultivatedincoffee forests(coffeetrees,plantedinaforest).Lessimportantarecoffee plantations.Coffeecoversaround40 %ofthetotalcatchmentarea. Land Use and Crop Production 21Other perennial crops are bananas, oranges, mangoes etc. Horticulture is also established in the catchment, but it covers only a small area. Results of the land use distribution analysis for the years 1989 and 1995 aregiveninFigure 10andTable 12.Itisnotpossibletoextrapolate trends from the results of these two single years. Results shown below are in percent of the catchment area. Figure 10:Dizi: land use in % of total catchment area in 1989 and 1995 Table 12:Dizi: land use in % of total catchment area in 1989 and 1995 19891995 Cereals23.427.4 Pulses0.10.2 Potatoes0.10.1 Perennial cultures1.30.0 Horticulture0.40.0 Coffee42.432.1 Grassland3.80.1 Woodland0.41.4 Fallow, bushes and shrubs21.331.0 Marshland5.67.1 No data1.20.5 0%10%20%30%40%50%60%70%80%90%100%1 2No dataMarshlandBushes, shrubs andfallowForest and afforestationGrasslandPerennial cropsCropland (annual crops)1989 1995The Agricultural Environment of Dizi, Illubabor, Ethiopia 22Crop Cover Itiswell-knownthatvegetationcoverismostimportantinreducing soilerosion.Dependingonthetypeofplantandwhenitgerminates, optimalsoilcoverisreachedatdifferenttimes.Figure 11shows interpolated soil coverage curves for different crops. Figure 11:Soil cover curves for selected crops in Dizi, interpolation Crop Yield and Biomass Production Cropyieldandbiomassproductiondependonvariousfactorssuchas climate, pests, diseases, weeding, fertiliser input, soil quality and depth, andsoilerosion.Conservationtechniquesandcropyieldwere systematically analysed in two different settings: Experimental plots (EP) Theeffectofthefollowingtypesofsoilandwaterconservation techniques on crop yield was tested on EPs, i.e. on plots with a surface of 6 by 30 m: 01020304050607080901000 50 100 150 200Days af ter germinationSoil cover in %Tef 1991Maize 1991Maize 1993Land Use and Crop Production 23one control plot with no conservation structures, one plot with graded Fanya Juu one plot with level Fanya Juu one plot with graded bunds one plot with level bunds one plot with grass strips ForEPresearchresultsseethechapteronSoilErosionandSoiland Water Conservation. Background information can be found in SCRP: Concept and Methodology. On-farm yield samples Crop yield samples were collected on cultivated land along the existing conservationstructures,i.e.terraces.Foreachcroppingseason, samples were taken at random from various farmers cultivated fields in thewholecatchment.Inbetweenconservationstructuresthree comparablesamplesweretakenondifferentlocations:one immediately above, one immediately below the conservation structure, and one inbetween two structures (for further information see SCRP: Concept and Methodology). Table 13:Mean annual yield [t/ha] per crop (1988 1991, Dizi) SorghumMaizeWheatTefHorse bean nMeannMeannMeannMeannMean 198812.8163.211.0140.7 198932.2162.360.421.5 1990273.1 199121.6391.911.8150.441.2 Table 13liststhemeanannualnetyieldpercrop.Calculationofyield tookintoconsiderationthatconservationstructuresonexperimental plotsuseuppartofthefields;thesizeofthisunproductivearea dependsonslopeandresultingspacingoftheSWCstructures(for further information see SCRP: Concept and Methodology). The Agricultural Environment of Dizi, Illubabor, Ethiopia 24Further reading Research Reports Erni, T. 1983 / Galizia, M. 1986 / Kappel, R. 1996 / Krger, H.-J. et al. 1997 / Ritler, A. 1997 / Tsehai Berhane-Selassie. 1994 Manuals Herweg, K. 1996 / Hurni, H. 1986 Thesis Yohannes G/Michael. 1992 Maps Hurni, H. 1995 Land Use and Crop Production 25The Agricultural Environment of Dizi, Illubabor, Ethiopia 26Soil Erosion and Soil and Water Conservation ThissectiongivesanoverviewofsoilerosionintheSCRPresearch catchment in Dizi, based on an analysis of monthly and annual data. The present database report does not aim at more detailed results such as analysisonstormorperiodbasis.Thereadershouldbeawarethat extrapolatingtheinformationgivenheremayleadtoerroneous conclusionsifdonewithoutknowledgeofscientificmodels,andwith no background knowledge about the research methodology. When computing annual values, incomplete years were not considered. Nonetheless,allplausiblemonthlyvalueswereincludedtodetermine monthlymeans.Usuallythefirstyearofmeasurementandtheperiod ofwarandinsecurity(in1991andpartof1992)werenotincludedin the analysis of annual totals. In this publication, the term runoff is synonymous with overland flow measured on test plots. At catchment level, the term river discharge is used for the volume of water passing the gauging station at the outlet ofthecatchment.Thetermsoillossreferstotheamountof sediment moving from the plots into the collection tanks, and the term sediment yield refers to the suspended sediment passing the gauging station at the outlet of the catchment. Surfaceflow(fieldrunoff,riverdischarge)anderodedmaterial(soil loss,suspendedsedimentyield)aretwoofthemainindicators continuouslymonitoredinallSCRPresearchstations.Theyare measured at different levels: micro-plots (MP, 1 x 3 m), test plots (TP, 2 x 15 m), experimental plots (EP, 6 x 30 m), researchcatchmentlevel(rivergaugingstation)beforeandafter conservation treatment. ThelocationofallplotscanbestudiedinAnnex2:LocationofField Plots.ForfurtherinformationseeSCRP:Conceptand Methodology. Soil Erosion and Soil and Water Conservation 27Table 14:SoilerosionandconservationinDizi:typeofdatacollected,durationof collection, and technique of measurement ParameterDevice / method Availability in database* Data source file (mainly primary database)** Resolution / frequency of data collectionSoil loss and runoff Micro-plot (MP), measurement in plot tanks 01/06/1988 - 31/12/1991 diyyslpl.dbfPlot emptying periods Soil loss and runoff Test plot (TP), measurement in plot tanks 01/06/1988 - 31/12/1993 diyyslpl.dbf and diyy_a03.dbf Plot emptying periods Soil loss and runoff Experimental plot (EP), measurement in plot tanks 01/06/1988 - 31/12/1993 diyyslpl.dbf and diyysssr.dbf Plot emptying periods Amount and intensity of rainfall Pluviometer/ Pluviograph (monthly chart rolls) 01/06/1988 - 15/12/1994 diyyplre.dbf***Segments wth similar intensity of ranfall ErosivityCalculation on the basis of rainfall intensity and duration 01/06/1988 - 31/12/1993 diyy_a03.dbfIndividual storms*** Yield (grain, straw, biomass)EP Experimental plots26/10/1988 - 21/11/1994 diyycaha.dbfWeekly, seasonally DischargeRiver station01/01/1989 - 31/12/1993 ilyyrsrd.dbfPermanent measurement (chart rolls) Sediment yieldRiver station01/01/1989 - 31/12/1993 ilyyrsrd.dbf10 minute intervals as long as water is classified as brown Notes:*Due to political and institutional problems, not all data collected are available in a digital format. **In the file names the letters di stand for the station name (Dizi), yy for the year, and the other four letters identify the content of the respective file (e.g. filename di87plre.dbf = Dizi / 1987 / pluviograph rainfall erosivity). ***This file contains records of the amount of rainfall for each rainfall interval of constant intensity within the same rainfall event. These amounts are summarised as storm values for further analysis. Definition of a storm: the minimum amount of rainfall must be 12.5 mm; one event must be separated from the next or the previous one by at least 6 hours. Test Plot Results Soil erosion measured on test plots in Dizi was generally close to zero, except during the first year when plots were installed. The Agricultural Environment of Dizi, Illubabor, Ethiopia 28Becausethisresearchstationwasestablishedatalatestage(mid-1988), analysis of data covers only four years. This should be taken into accountwheninterpretingtheresultsshowninthefollowingTables and Figures. Annual Data Figure 12:Annual rainfall, erosivity, runoff, and soil loss on test plots (1989 1993, Dizi) Soil Erosion and Soil and Water Conservation 29Twoofthefourplotswerecoveredwithannualcrops(TP 1,18 % slopeandTP 4,42 %slope),whiletheothertwoplotshadacoffee plantation (TP 3, 42 % slope) and grass (TP 2, 32 % slope). Thesecondhighestmeanannualrainfallandthehighestmeanannual erosivityofallSCRPstationsweremeasuredinDiziresearchstation. DuringanextendedrainyseasonlastingfromMarchtoOctober,the peaksofrainfall,erosivity,runoffandsoillosswereregisteredin August,andvaluesslightlydecreasedinSeptember.Inviewofthe tremendousamountofrainanderosivity,however,soillosseswere veryslight.Eventhehighestrecordedannualsoillosswasbelow10 t/ha, and the steepest cultivated plot (TP 4, 42 % slope) did not show anyerosioninfouroutoffiveyearsofmeasurement.Highvegetation coveristheexplanationforthisremarkableresult.Duetosufficient moisture,a groundcoverofweedsdevelopedquicklyafter ploughing, speeding up sedimentation of eroded particles and preventing high soil losscausedbysplasherosiononbaresoils.However,theweedsthat protectedthesoilfromerosionwereamajorproblemforcrop production. Annual results varied considerably. An example may therefore support furtherinterpretationoftheresults,keepinginmindthatthesoilloss values were so low that erosion cannot be considered a major problem (see Figure 12 and Table 15). Table 15:Annual rainfall, erosivity, runoff, and soil loss on test plots (1988 1993, Dizi) TP 1, 18 % slopeTP 2, 32 % slopeTP 3, 42 % slopeTPYearRainfall [mm] Erosivity [J/mh] Crop type Runoff [mm] Soil loss [t/ha] Crop type Runoff [mm] Soil loss [t/ha] Crop type Runoff [mm] Soil loss [t/ha] Croptype 19891665.3874.5mz91.14.5gr124.10.0co26.20.0sg19901302.1488.1mz19.10.2gr100.30.2co13.60.0mz19911593.4827.6te80.83.9gr123.10.1co23.80.0mz19921464.1522.6fl87.49.3gr77.70.0co18.60.0mz19931535.4517.0fl90.50.0gr85.30.0co28.50.0mzMean1512.1646.073.83.6102.10.122.10.0 SD124.1168.527.63.419.00.15.40.0 CV0.10.30.41.00.21.30.2 Mean Dev103.2164.121.92.817.20.14.80.0 Rel Dev0.10.30.30.80.21.20.2 Median1535.4522.687.43.9100.30.023.80.0 The Agricultural Environment of Dizi, Illubabor, Ethiopia 30 Monthly Variation of Test Plot Results Measurement started in June 1988; during that year monthly soil losses ofupto90 t/hawereregistered.Thisorderofmagnitudewasnever recorded again, not even closely. The great soil loss in the first year can thereforebeinterpretedasresultingfromplotconstruction(see Figure 13andTable 16).Therelativelyhighaveragevaluesshownfor August and September are thus heavily influenced by the results of that first year. Figure 13:Mean monthly rainfall, erosivity, runoff, and soil loss on test plots (June 1988 -end of 1993, Dizi) Soil Erosion and Soil and Water Conservation 31Table 16:Meanmonthlyrainfall,erosivity,runoff,andsoillossontestplots(June 1988 1993, Dizi) Month TP 1, 18 % slopeTP 2, 32 % slopeTP 3, 42 % slopeTP 4, 42 % sloRainfall [mm] Erosivity [J/mh] Runoff [mm] Soil loss [t/ha] Runoff [mm] Soil loss [t/ha] Runoff [mm] Soil loss [t/ha] Runoff [mm] Soil l[t/haJan13.60.00.00.00.00.00.00.00.00.Feb18.56.60.10.00.00.00.10.00.00.Mar62.218.60.20.00.30.00.30.00.20.Apr108.350.91.80.90.80.00.90.00.40.May184.282.411.51.84.40.02.90.02.70.Jun196.867.010.70.55.00.03.60.02.70.Jul238.7102.112.50.210.60.03.20.02.00.Aug310.6165.751.615.254.80.15.80.19.41.Sep249.5131.849.85.045.80.05.70.19.91.Oct139.261.121.50.821.40.03.30.111.20.Nov23.90.00.20.00.10.00.10.00.00.Dec29.114.20.20.00.50.00.30.00.10. The erosion pattern on the test plots is similar to the pattern observed inotherstations,inthesensethatmostlosseswerecausedduringa fewrainfallperiods;buttheorderofmagnitudewasmuchlowerin Dizi than in all other SCRP research stations. Again, it must be kept in mindthatsoillossvaluesweresolowthaterosioncannotbe considered a major problem in Dizi. On TP 1 in 1992 (fallow), of the annual 9.3 t/ha ofsoil loss, 46 % was registeredinApriland50 %inMay.OnTP 4in1991(maize),ofthe annual5.3 t/haofsoilloss,55 %wasregisteredinMayand45 %in June.Duringthemonthsdiscussedabove,rainfallanderosivitywas higherthanthemonthlymeanonlyinMay1991.Singleeventswere the most influential factors contributingtothe erosionprocess for the remaining months. The Agricultural Environment of Dizi, Illubabor, Ethiopia 32Micro-plot Results Annual Data InDizionlytwomicro-plotswereestablished.Themeasurement periodlastedonlyfrom1989to1991.Thefollowingplotpairs(test plot / micro-plot) can be compared: TP 1 / MP 5 and TP 4 / MP 6 (see Table 17). Table 17:Meanannualrunoffandsoillossontestplotsandcomparablemicro-plots (1989 1991, Dizi) TP 1MP 5TP 4MP 6 Runoff [mm]63.7249.113.481.3 Soil loss [t/ha]2.910.71.87.0 Annual MP values for both runoff and soil loss are higher than those of therespectiveTPs.Thisindicatesthatmuchofthematerialdetached byrainsplashandsheetwashwasre-depositedasaresultofdense vegetationcover.Denserootingsystemscausedhighinfiltrationand limitedrunoff.Asaresult,transportcapacityandentrainmentwere also limited and soil loss in t/ha decreased with slope length, at least up to the length of test plots (15 m). See also Table 18. Table 18:Annual rainfall, erosivity, runoff, and soil loss on micro-plots (1989 1991, Dizi) MP 5, 18 % slopeMP 6, 42 % slope Year Rainfall [mm] Erosivity [J/mh] Crop type Runoff [mm] Soil loss [t/ha] Crop type Runoff [mm] Soil loss [t/ha] 19891665.3874.5mz325.323.2sg104.41.6 19901302.1488.1mz160.52.6mz44.60.6 19911593.4827.6te261.56.3mz95.018.8 Mean1520.3730.1249.110.781.37.0 SD157.0172.267.89.026.38.4 CV0.10.20.30.80.31.2 Mean Dev145.4161.359.18.324.57.9 Rel Dev0.10.20.20.80.31.1 Median1593.4827.6261.56.395.01.6 Soil Erosion and Soil and Water Conservation 33Monthly Variation of Micro-plot Results Table 19 shows the monthly values of rainfall, runoff, erosivity and soil loss.Onlythreemeasurementyearsareavailable;thisperiodistoo shortforreliablestatisticalvalues.Duetovariableenvironmental conditions,alongerperiodofmeasurementwouldbenecessaryto establish a database with a high level of relevance. ThebulkofsoilerosionoccurredfromAugusttoSeptember.More than50 %wasmeasuredinAugust.ErosivityinMayandOctober werecomparable,butsoillossinMaywashigherbecausesoilcover was lower during that month. Figure 14:Meanmonthlyrainfall,erosivity,runoff,andsoillossonmicro-plots(1989 1991, Dizi) The Agricultural Environment of Dizi, Illubabor, Ethiopia 34Table 19:Meanmonthlyrainfall,erosivity,runoff,andsoillossonmicro-plots(1989 1991, Dizi) MP 5, 18 % slopeMP 6, 42 % slopeMonthRainfall [mm] Erosivity [J/mh] Runoff [mm] Soil loss [t/ha] Runoff [mm] Soil loss [t/ha] Jan13.60.00.00.00.00.0 Feb18.56.61.20.20.30.0 Mar62.218.66.00.13.10.5 Apr108.350.94.30.03.50.0 May184.282.430.95.914.55.4 Jun196.867.034.62.214.51.0 Jul238.7102.139.30.712.10.1 Aug310.6165.7117.024.945.85.5 Sep249.5131.882.97.844.02.4 Oct139.261.123.80.720.20.3 Nov23.90.01.10.00.30.0 Dec29.114.21.80.00.80.0 Soil Conservation Experiments on Experimental Plots and Farmers Fields The size of the experimental plots is 6 x 30 m. Slope and soil type on all experimentalplotsareconstant:theslopeis18 %,thesoiltypeis Lixisol.Eachplothasaspecificconservationstructure.InDizisix experimental plots (one set) were established in 1989 and featured the following techniques: one control plot with no conservation structures, one plot with graded Fanya Juu, one plot with graded bunds, one plot with level Fanya Juu, one plot with level bunds, one plot with grass strips. Interpretationofdatafromexperimentalplotsmustbesubmittedto thefollowingrestriction:itisproblematictocomparegraded structuresandlevelstructuresonaone-to-onebasis.Indeed,under on-farmconditions,gradedterraceshaveawaterwayevery50to 100 m in order to drain excess water. In contrast, the EPs have a width Soil Erosion and Soil and Water Conservation 35of6 monly,whichmeansthatthecorrespondingwaterwayisonlya small drainage ditch. The relation of the drainage ditch to its catchment is thus distorted. Furthermore, EPs with level structures cannot exactly simulatenormalon-farmconditionssuchasoverflowbecauseoftheir relativelysmallplotsize.Therefore,EPvaluesonlyhintatthedegree of erosion on terraces. Runoffandsoillossvaluesonallexperimentalplotswereverylow, evenonthecontrolplot(seeFigure 15andTable 20).Highervalues weremeasuredonlyin1991,butallconservationmeasures considerablyreducedrunoffandsoilloss-thegrassstripalittleless than the mechanical structures. Annual Runoff and Soil Loss on Experimental Plots Table 20:Absolute and relative annual runoff and soil loss on experimental plots (1989 -1993, Dizi) Runoff [mm]Soil loss [t/ha] Year CropControl plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund Grass strip Control plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund 1989mz20.517.243.632.716.412.70.40.50.90.60.1 1990mz14.110.725.126.815.511.40.10.00.30.40.0 1991mz138.644.446.482.927.457.024.81.82.12.80.8 1992te43.79.412.410.79.912.20.00.00.00.00.0 1993mz9.110.08.48.37.54.60.00.00.00.00.0 Mean45.218.327.232.315.319.65.10.50.70.80.2 SD48.213.315.627.06.918.99.90.70.81.00.3 CV1.10.70.60.80.41.02.01.51.21.41.7 Mean Dev 37.410.414.320.45.315.07.90.60.70.80.2 Rel Dev0.80.60.50.60.30.81.61.21.01.11.4 Median20.510.725.126.815.512.20.10.00.30.40.0 Runoff (% of control plot)Soil loss (% of control plot)YearCrop Control plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund Grass strip Control plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund 1989mz10083.9212.7159.580.062.0100125.0225.0150.0 1990mz10075.9178.0190.1109.980.91000.0300.0400.0 1991mz10032.033.559.819.841.11007.38.511.3 1992te10021.528.424.522.727.9 1993mz100109.992.391.282.450.5 % of control plot (mean) 10040.660.171.433.943.31009.113.015.03.6 The Agricultural Environment of Dizi, Illubabor, Ethiopia 36 Figure 15:Absolute and relative annual runoff and soil loss on experimental plots (1989 1993, Dizi) Soil Erosion and Soil and Water Conservation 37Yield and Biomass on Experimental Plots Figure 16:Absoluteandrelativeannualcropyieldandbiomassproductionon experimental plots (1988 - 1993, Dizi) The Agricultural Environment of Dizi, Illubabor, Ethiopia 38Figure 16andTable 21showtheinfluenceofdifferentsoilandwater conservation (SWC) experiments in Dizi. Again the short measurement periodimposeslimitationsontheinterpretationoftheresults,and makes it impossible to extrapolate. On average, production on plots with SWC structures remained lower thanonthecontrolplot.Exceptionsweremaizeandtefin1990and 1992,whenthesecropsreachedhigheryieldsonmostoftheplots comparedtothecontrolplot.Thehighrunoffin1993resultedinthe lowestmaizeproductionontheEPs.Apparently,runoffreductiondid not only lead to reduced erosion but also to waterlogging. Table 21:Absoluteandrelativeannualcropyieldandbiomassproductionon experimental plots (1988 - 1993, Dizi). Yield [t/ha]Biomass [t/ha] Crop type Control plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund Grass strip Control plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund Grass strip te0.40.30.30.30.30.32.11.91.71.71.92.0 mz1.71.40.91.31.11.17.76.45.55.96.16.1 mz1.51.71.31.71.51.54.66.56.05.85.34.7 mz1.60.90.61.00.61.26.56.53.05.01.84.3 te0.10.10.10.10.10.10.40.50.50.50.50.5 mz0.60.50.30.50.30.5 1.00.80.60.80.60.84.34.43.33.83.13.5 Yield (% of control plot)Biomass (% of control plot) Crop type Control plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund Grass strip Control plot Graded Fanya Juu Graded bund Level Fanya Juu Level bund Grass strip te10084.284.276.389.586.810091.384.585.194.395.7 mz10081.155.674.663.363.310082.970.576.379.078.6 mz100116.388.4112.9103.4100.7100142.1129.2126.4115.5101.4 mz10056.437.458.936.274.210099.045.875.827.766.1 te10066.7111.177.8100.0122.2100119.9120.3120.3127.9133.3 mz10076.755.088.341.780.0 ontrol mean) 10082.661.481.465.979.9100102.177.988.673.582.3 Conclusive Remarks on Experimental Plot Results Comparisonsshouldbemadeeitherbetweengradedstructuresand controlplotandgrassstrip,orbetweenlevelstructuresandcontrol plotandgrassstrip.Thedecisionwhetherlevelorgradedstructures should be implemented must take into account the rainfall regime. For Soil Erosion and Soil and Water Conservation 39example,areaswithhighrainfallneedgradedversionstodrainexcess water,whereaslowrainfallareasrequirelevelstructurestoretain moisture.Differences insoil lossandrunoffbetweengradedandlevel EPs are not adequate criteria for such a decision. Despitehighrainfallanderosivity,extensivegroundcoverprevents high runoff rates in the area.Thisindicates that erosion is nota major issueintheDiziarea.Instead,atpresent,themajorproblemsinthis region are: rapid decrease in soil fertility through leaching, the problem of weeds, the damage to crops by wild animals. MechanicalconservationdoesnotseemnecessaryfortheDiziarea giventhelowsoillossvalues;howeveronemustbearinmindthat measurementsweremadeonlyduringashortperiod.Aslongasa farmingsystemwithlongfallowperiodsismaintained,theneedfor mechanicalconservationwillremainlow.Underthepresent circumstances, mechanical SWC measures may even be redundant and constituteanobstacletoproduction,becausetheycancausewater-loggingduringthoseyearswhentheyefficientlyreducesoilloss. EmphasisshouldthusbegiventobiologicalSWC,suchasimproved weed control. But improved weed control will lead to much higher soil loss rates. This should be stated for future intensification measures. ApartfromtheEPresults,theTPresultsalsosuggestthatunderthe current land use system, soil erosion is not a major problem in the Dizi area.Rillerosionwasrarelyobserved.However,theflatnessofthe valley floors indicates that considerable amounts of soil must have been moved from the slopes, to such an extent that during the dry months, cultivation is possible there. These accumulations may be a result of soil movementsaftereveryclearingofforestcoverorofglacialdeposits from 15000 BP. The Agricultural Environment of Dizi, Illubabor, Ethiopia 40Results of Hydrometric Measurements on the Catchment The total size of the Dizihydrological catchment is672.7 ha. Table 22 liststhemonthlyandannualdischargeofthehydrometricstationfor the period from 1989 to 1992. Table 22:Monthly and annual catchment discharge [mm] (1989- 1992, Dizi). Source: Bosshart, 1997 FebMarAprMayJunJulAugSepOctNovDecYear 2.23.11.81.82.73.911.58.65.63.13.751.1 1.61.03.06.310.113.215.69.35.72.51.872.0 1.43.14.27.411.111.318.613.88.04.94.789.9 3.03.02.87.36.06.88.513.613.17.34.880.3 2.12.63.05.77.58.813.611.38.14.43.773.3 0.71.01.02.63.94.24.52.73.52.21.416.5 535.440.032.946.451.747.732.824.243.448.736.722.5 3.03.14.27.411.113.218.613.813.17.34.889.9 1.41.01.81.82.73.98.58.65.62.51.851.1 Mean monthly discharge (Q, l/sec), mean monthly discharge volume (Qv, m) and mean monthly discharge yield (q, l/skm) for the period 1989-1992: 75.746.417.7714.3219.3422.1234.1029.3620.3411.529.4015.64 3391389217172201453834950119592599132776097544672985725181493204 60.850.951.162.132.873.295.074.363.021.711.402.32 Figure17 showstheannualrainfallandcorresponding,thecatchment discharge and suspended sediment yield: The annual discharge varied between 51 mm (1989) and 90 mm (1991). Theannualsuspendedsedimentyieldrangedbetween0.001 t/ha (1992) and 0.003 t/ha (1989). Theannualsedimentconcentrationvariedbetween0.002 g/l (1991/92) and 0.006 g/l (1989). HighrainfallanderosivityinDiziareonlyslightlyreflectedinriver discharge and sediment yield, the latter being the lowest measured in all SCRPstations.Mostofthesmallamountofmaterialerodedfromthe cultivated area immediately re-accumulates on the fields, or is deposited inthevalleybottomsandtheswampyareainthecatchmentoutlet.As Figure 18 and Table 23 show, the peak of river discharge was in August, while sediment yield increased slightly in August and May. Soil Erosion and Soil and Water Conservation 41 Figure 17:Annualrainfall,catchmentdischarge,andsuspendedsedimentyield(1989 -1992, Dizi). Source: Bosshart, 1997 Figure 18:Meanmonthlycatchmentdischargeandsuspendedsedimentyield(1989 -1992, Dizi). Source: Bosshart, 1997 The Agricultural Environment of Dizi, Illubabor, Ethiopia 42Table 23:Monthlyandannualsuspendedsedimentyield(1989 - 1992,Dizi).Source: Bosshart, 1997 JanFebMarAprMayJunJulAugSepOctNovDecYear 8900.000100.0001300.000540.000400.000260.000610.000170.0001300.000530.00288 90000000.000020.000550.001640.000080000.00229 910000.000010.001440.00009000.000030000.00158 920000.000080000.000170.000800.00039000.00144 an00.000020.000030.000020.000500.000130.000200.000610.000270.0001300.000130.00205 00.000050.000070.000040.000680.000190.000260.000740.000360.0001800.000270.00067 [%]200.0200.0162.9137.1145.5129.3121.7133.2140.5200.032.7 x00.000100.000130.000080.001440.000400.000550.001640.000800.0003900.000530.00288 n000000000.000030000.00144 Mean monthly suspended sediment rate (Qs, t), mean monthly suspended sediment concentration (Cs, g/l): 00.0160.0220.0160.3340.0860.1360.4080.1800.08800.0891.377 00.0010.0010.0010.0090.0020.0020.0040.0020.00200.0040.003 Further reading Research Reports Bosshart, U. 1997 / Hagmann,J. 1991 / Herweg, K., Ostrowski, M.W. 1997/Herweg,K.,Stillhardt,B.1999/KefeniKejela.1996/Krger, H.-J. et al. 1997 / Tsehai Berhane-Selassie. 1994 African Studies Series Solomon Abate. 1994 Manuals Herweg, K. 1996 / Hurni, H. 1986 Papers El-Swaify, S.A., Hurni, H. 1996 / Herweg, K. 1993, 1995 / Herweg, K., Ludi, E. 1999 / Hurni, H. 1988a / Hurni, H., Kebede Tato (eds.). 1992 Theses Bekele Shiferaw. / Getachew Gurmu. 1991 / Yohannes G/Michael. 1992 Maps Hurni. 1995 / SCRP. n.d Soil Erosion and Soil and Water Conservation 43 The Agricultural Environment of Dizi, Illubabor, Ethiopia 44Social and Economic Characteristics TheDizicatchmentissituated in theMetuareaofIllubaborRegionin western Ethiopia and covers 672.7 ha. The southwestern region is one ofthemostsparselypopulatedareainthecountry.Spontaneous immigration was more frequent in the 20th century. Most settlers, such astheOromosfromWelegaandtheAmharasfromShewa,Gonder and Gojam, came from far away. Enforced and induced immigration by different government was also important throughout the century. Traditionally,shiftingcultivationhasbeenthepredominantfarming system.Butnumerouslandusereformssincethe1930shavehada significantimpactontheconditionsoflandownershipandlanduse; theyhavealsocontributedtoaconsiderabledegreeofethnicmixing andculturaltransfer.Themixedfarmingeconomyincreasinglybased ontheox-drawnplough,andmorepermanentformsofcultivation werethemostsignificantchanges.Thegrowingimportanceofcoffee attracted immigrants as seasonal labourers, with some of them settling permanently. Therurallandproclamationof1975markedaturningpointbecause modernruralinstitutionsweresetup.Privatelandwasturnedinto publicproperty,andthetenant-landlordrelationshipswereabolished. User rights were given to formerly landless peasants and tenants. Food cropproductionforconsumptionundersmall-scalefarmingstartedto replacelargecommercialcoffeefarmsownedbyabsencelandlords. Immigrationintotheregionpracticallyceasedatthispoint,sincethe proclamation prohibited hiring of labourers by individual farmers. Additionally, the area had to absorb a high immigration rate due to the resettlementprogrammelaunchedbytheGovernmentofEthiopia between 1984 and 1986. Over half a million people, originally from the northernpartsofthecountry,whicharepronetodroughtand subsequentfamine,werere-settledtothesouthwesternpart,where biophysicalconditionsseemedtobebetter.Theresettlement programme significantly influenced the demographic situation. Today it isclearthattheimpactofthischangeontheecosystemisvery Social and Economic Characteristics 45dramaticbecauseagriculturehasbeen intensifiedandforestcoverhas been dramatically reduced. This trend will continue if the present rate of population growth is not reduced. Theopportunitytosellwoodproductssuchascharcoal,fuelwoodor householditemsforsupplementaryincomeincreasesthepressureon theremainingforestareas.TheIllubaborregionisamajorsupplierof coffee,whichisthemainsourceofforeignexchangeforthenations economy.Competitionbetweenfoodcropsandcoffeethreatensthe traditional fallow system, which limits the total area available for cultivation. Thus, land use in the area must be characterised as highly dynamic. Intheshortterm,thepeasantseconomicsituationisfavourable. Farmland is still available in sufficient quantities, and new opportunities arepromising.Forthehouseholdeconomy,themainproblemsare shortageofoxenandlimitationstocattlebreedingduetodiseases,as well as shortage of labourers, especially for such tasksas weeding and guarding crops day and night from wildlife. Iflandmanagementisnotimproved,somedominantfactorssuchas recentimmigrationflows,populationincrease,intensivefarming, market expansion, the growing cash crop economy, and a problematic perceptionofwhatconstitutesfertileandopenland,endanger Illubabors natural resources in the long-term. Collection of Social and Economic Data EvenifDiziisconsideredabenchmarksiteforSCRP,thecatchment was not part of the standard socio-economic programme. However, in 1990,anin-depthsocio-economicsurvey(SolomonAbate,1994) comparedtheDizicatchmenttotheneighbouringGeycatchment,a tributaryoftheriverSor.Withanareaofalmost7sq.km,Dizi catchmentisrepresentativeforareasrecentlysettledunderthe resettlement programme, whereas the Gey catchment, with its 9.7 sq.km representstheareasnotaffectedbytheresettlementprogramme.The environmentalconditionsinDiziarelessfavourablethanintheGey catchment, which attracted more settlers in earlier times. The Agricultural Environment of Dizi, Illubabor, Ethiopia 46Thesocio-economicsurveyincluded18peasantassociations(PA) located in the study area. Ten households (HH) were selected in each PA,bringingthetotalsampleofhouseholdscoveredbythesurveyto 180.Thisrepresents5 %ofallhouseholdsinthestudyarea. Additionally,toassessthesocio-economicdifferencesbetweenthe two catchments, an in-depth survey of 20 farms distributed in two PAs wasconducted.Anotherin-depthstudywasconductedin1990, investigatingtheeffectsoffallowandcultivationperiods(Getachew Gurmu,1991).Bushfallowisstillprevalent inDizi, whilecultivation is highly intensified in the Gey catchment. Diziwasalsocoveredbyasocialsurveyconductedbyasocial anthropologist (Tsehai Berhane-Selassie 1994). Demographic Features Size of Families and Population Density Figure 19:Size of families in the research area in Dizi and Gey (1990) In1990,thepopulationdensityinthestudyarea(150 sq.km)was estimated to be around 80 persons per sq.km. In the Ethiopian context thiswasratedasamediumdensityatWeredalevel.Inthesampled catchments,thepopulationdensitywascalculatedtobeabout70 Social and Economic Characteristics 47persons per sq.km. The average size of family was 6.7 persons. Nearly 75 % of the households comprised 4 to 8 persons. Table 24:Size of families per household in Dizi and Gey (Solomon Abate, 1990) No. of family members per household FrequencyPercentage 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0 3 13 18 28 27 37 19 5 13 6 4 3 1 0 1 0 1 0 % 2 % 7 % 10 % 16 % 15 % 21 % 11 % 3 % 7 % 3 % 2 % 2 % 1 % 0 % 1 % 0 % 1 % Recorded Households: 179 (total 1207 persons) Average: 6.7 persons per household Age and Gender Structure All households were headed by men; together with the size of families, this indicates that impoverishment has not reached the extent it has in otherregions.Incompletefamilies,whichareespeciallyproneto poverty,arestillrare.Theslightdifferencesbetweenthenumberof malesandfemalesineachagecategory,especiallythehighernumber ofmalesinthe18 - 60categoryandthehighernumberoffemales under 18, must be attributed to the tendency to underestimate the age of girls and overestimate boys ages. The Agricultural Environment of Dizi, Illubabor, Ethiopia 48 Figure 20:AgeandgenderstructureofthesamplepopulationinDiziandGey(1990, Solomon Abate) Table 25:AgeandgenderstructureofthesamplepopulationinDiziandGey(1990, Solomon Abate) FrequencyPercentage Age group malefemalemalefemale < 1831434126 %28 % 18 - 6025522821 %19 % > 6045244 %2 % Total61459351 %49 % Recorded households179 (total 1207 persons) Linguistic and Religious Structure of the Population Figure 21:Distribution of inhabitants in Dizi and Gey (Metu area) according to language and religion (1990) Social and Economic Characteristics 49With regard to ethnic and religious identities, the populationstructure in each catchment is very different, due to differences in their histories ofimmigration.IntheDizicatchment85 %ofthepopulationare Oromosand15 %Amharas,whereasinGeytheratiois70to30.In Dizi we find 60 % Christians and 40 % Moslems, while Gey has a ratio of 90 % to 10 %. Table 26:Distribution of inhabitants in Dizi and Gey (Metu area) according to language and religion (1990, Solomon Abate) Linguistic groupsNo. of HHReligious groupsNo. of HH Oromifa Amarigna Tigrigna Guragigna 135 34 9 1 75 % 19 % 5 % 1 % Orthodox Christians Moslems Protestants 121 49 9 68 % 27 % 5 % Total179 Total179 Livestock Holdings AsinallotherpartsoftheEthiopianhighlands,livestockisanintegral partofthecroppingsystem.Inthestudyarea,livestockisnotlimited byinsufficientgrazingland,butbythepervasivenessofthelivestock disease Trypanosomiasis, locally known as gendi. Figure 22:Dataonlivestockstructureforselectedhouseholdsintheresearcharea (1990, Getachew Gurmu, Dizi) The Agricultural Environment of Dizi, Illubabor, Ethiopia 50Livestockcomprisesmainlycattle.Cattleareusuallyallowedtograze openly, thus only a small percentage of the manure is collected; but the systemofshiftingstockpenswithinfieldsisasmartwayofefficiently utilisingmanure.Livestockalsocontributestothecashincomeofthe community.Farmersobtainnearly20 %oftheirannualcashincome fromsellinglivestock.Theyusuallysellfarmanimalstocoverlarger expenses such as land taxes. Oxenarethemainsourceofdraughtpower,butnearly22 %ofthe familiesdonotpossessanox,and34 %ofthehouseholdshaveonly one ox. 37 % of the households have a pair, and 8 % have more than twooxen.Thismeansthat56 %ofthehouseholdsdependonother familiesoxenforploughing,causingdependenciesandmakingit difficult to plough at the right time. Table 27:Data on livestock structure (1990, Getachew Gurmu, Dizi) Livestock typeNo. of animals ox cow bull heifer horse donkey mule sheep goat 80 84 0 11 3 31 9 61 7 Total Livestock286 Social and Economic Characteristics 51 Figure 23:Dataonoxenholdingsforselectedhouseholdsintheresearcharea(1990, Solomon Abate, Dizi) The Agricultural Environment of Dizi, Illubabor, Ethiopia 52Table 28:Data on oxen holdings in the research area (1990, Solomon Abate, Dizi) Number of oxen per householdNumber of households 0 1 2 3 4 5 6 7 8 40 60 67 4 6 1 0 0 1 22 % 34 % 37 % 2 % 4 % 1 % 0 % 0 % 1 % Total oxen: 243 in 179 households Average: 1.4 oxen per household Landholdings In1990theaveragesizeoflandholdingsperhouseholdwasnearly 2.6 ha, with plots inside and outside the research unit. Nearly 80 % of the sample households had 2-4 ha of land. The average farm size (area undercrop)increasedfrom1988to1990.In1988theaveragewas around1.4 ha;64 %ofthehouseholdsreportedanincrease,while 19 %reportedadecreaseoftheirfarmsize.Mostoftheincreasein farmareadevelopedattheexpenseofthefallowperiods.Onlyfew respondentsreportedhavingclearedforestareastoincrease landholdings. Thus the actual size of the holdings did not change much, buttheextratimeavailableafterdismantlingco-operativeworkin 1989 gave the families opportunities to cultivate larger surfaces and to managethemmoreappropriately.Thenewgovernmentpolicyalso promotedthisbysupportingamixedeconomyandaccesstofree markets. Social and Economic Characteristics 53 Figure 24:Dataonlandholdingsforselectedhouseholdsintheresearcharea(1990, Solomon Abate, Dizi) Table 29:Landholdings per household (1990, Dizi) Sample size: 179 HH (Solomon Abate) Sample size: 130 HH (Getachew Gurmu) [ha]frequency[ha]frequency < 1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 >9 0 11 58 54 31 13 4 3 4 1 0 % 6 % 32 % 30 % 17 % 7 % 2 % 2 % 2 % 1 % < 3 3-6 6-8 >8 45 67 11 7 35 % 52 % 9 % 5 % Thehouseholdsreportingadecreaseinfarmsizegavethefollowing reasons: Shortage of manpower: 29.4 % Shortage of oxen: 26.5 % Decline in soil fertility: 17.4 % Villagisation: 17.4 % Wildlife: 4.8 %Grazing: 2.9 % The Agricultural Environment of Dizi, Illubabor, Ethiopia 54It is obvious that under the circumstances found in the study area, large families were privileged. Families with no shortage of labour intensified cropproductionontheirfieldsbyshorteningthefallowperiod. Newcomers in particular concentrated on new opportunities and were notawareof,ordisregardedlong-termimpacts.Forfamilieswitha shortageoflabour(oxenandhuman)economicdevelopmentwas impossible;furthermore,taskssuchasweedingandguardingfields fromwildlifeduringthewholegrowingperiodconstitutedaserious bottleneck, and hindered any attempt to farm larger plots. Further reading African Studies Solomon Abate. 1994 Research Reports Getachew Gurmu. 1991 / Tsehai Berhane-Selassie. 1994 Bibliography 55Bibliography of the Soil Conservation Research Programme Progress Reports Hurni, H. 1982a. Inception Report. Soil Conservation Research Project, Vol. 1. University of Berne, Switzerland. Hurni, H. 1982b. First Progress Report (Year 1981). Soil Conservation Research Project, Vol. 2. University of Berne, Switzerland. Hurni,H.1983.SecondProgressReport(Year1982).SoilConservation Research Project, Vol. 3. University of Berne, Switzerland. Hurni, H. 1984. Third Progress Report (Year 1983). Soil Conservation Research Project, Vol. 4. University of Berne, Switzerland. Hurni, H. 1984. Compilation of Phase I Progress Reports (Years 1981, 1982 and 1983).SoilConservationResearchProject,Vol.1-4.Universityof Berne, Switzerland. Hurni,H.1986.FourthProgressReport(Year1984).SoilConservation Research Project, Vol. 5. University of Berne, Switzerland. Hurni,H.andGrunder,M.1988.FifthProgressReport(Year1985).Soil ConservationResearchProject,Vol.6.UniversityofBerne, Switzerland. Grunder, M. and Herweg, K. 1991a. Seventh Progress Report (Year 1987). Soil ConservationResearchProject,Vol.8.UniversityofBerne, Switzerland. Grunder,M.andHerweg,K1991b.EighthProgressReport(Year1988).Soil ConservationResearchProject,Vol.9.UniversityofBerne, Switzerland. Research Reports Berhanu Fentaw. 1991b. An Evaluation of Mulch on Cultivated Land in Two On-FarmTrialsinWesternGojam,DegaDamotAwraja(Anjeni,SCRP). University of Berne, Switzerland: Soil Conservation Research Project, Research Report 21. BerhanuFentaw.1991a.ASurveyofEarthwormsinWesternGojam,Dega DamotAwraja.UniversityofBerne,Switzerland:SoilConservation Research Project, Research Report 20. Bono,R.andSeiler,W.1983.TheSoilsoftheSuke-HarergeRU(Ethiopia). University of Berne, Switzerland: Soil Conservation Research Project, Research Report 2. The Agricultural Environment of Dizi, Illubabor, Ethiopia 56Bono,R.andSeiler,W.1984a.TheSoilsoftheAndit-TidRU(Ethiopia). University of Berne, Switzerland: Soil Conservation Research Project, Research Report 3. Bono,R. andSeiler, W.1984b.Suitabilityof the Soils in the Suke-Harerge and Andit-TidRU(Ethiopia)forContourBunding.UniversityofBerne, Switzerland: Soil Conservation Research Project, Research Report 4. Bono, R. and Seiler, W. 1984c. Erodibility in the Suke-Harerge and Andit-Tid RU (Ethiopia).UniversityofBerne,Switzerland:SoilConservation Research Project, Research Report 5. Bono, R. and Seiler, W. 1987. Aspects of the Soil Water Budget in Two Typical Soils of the Ethiopian Highlands. University of Berne,Switzerland: Soil Conservation Research Project, Research Report 14. Bosshart,U.1996.MeasurementofRiverDischargefortheSCRPResearch Catchments:MethodologyandTheoreticalBackground.Universityof Berne,Switzerland:SoilConservationResearchProgramme, Research Report 29. Bosshart,U.1997a.MeasurementofRiverDischargefortheSCRPResearch Catchments: Gauging Station Profiles. University of Berne, Switzerland: Soil Conservation Research Programme, Research Report 31. Bosshart, U. 1997b. Catchment Discharge and Suspended Sediment Transport as IndicatorsofPhysicalSoilandWaterConservationintheMayketin Catchment,AfdeyuResearchUnit.ACaseStudyintheNorthern HighlandsofEritrea.UniversityofBerne,Switzerland:Soil Conservation Research Programme, Research Report 39. Bosshart, U. 1997c. Catchment Discharge and Suspended Sediment Transport as IndicatorsofPhysicalSoilandWaterConservationintheMinchet Catchment,AnjeniResearchUnit.ACaseStudyintheNorth-western HighlandsofEthiopia.UniversityofBerne,Switzerland:Soil Conservation Research Programme, Research Report 40. Bosshart, U. 1998. Catchment Discharge and Suspended Sediment Transport as IndicatorsofSoilConservationintheDombeTwin-Catchmentsofthe GununoResearchUnit.ACaseStudyintheSouth-westernEthiopian Highlands.UniversityofBerne,Switzerland:SoilConservation Research Programme, Research Report 32. Bosshart, U. 1999. Hydro-sedimentological Characterisation of Kori Sheleko and HuletWenzCatchments,MaybarandAnditTidResearchUnits.Case Studies of two SCRP Micro-catchments in the North-eastern Highlands of Ethiopia. University of Berne, Switzerland: Soil Conservation Research Programme, Research Report 41. Erni, T. 1983. Land Cover Estimates with Landsat Pictures. University of Berne, Switzerland: Soil Conservation Research Project, Research Report 6. Galizia,M.1986.SocialAnthropologicalStudiesforSoilConservation:Man-Environment Relationships in the Western Chercher Mountains, Harerge (Ethiopia).UniversityofBerne,Switzerland:SoilConservation Research Project, Research Report 12. Bibliography 57Hagmann,J.1991.TheSoilsofDizi,Illubabor:TheirGenesis,Potentialand ConstraintsforCultivation.UniversityofBerne,Switzerland:Soil Conservation Research Project, Research Report 18. Hnggi, F. 1997. Temporal and Spatial Variations of Soil Erosion in the Research UnitsAnjeniandAnditTid.UniversityofBerne,Switzerland:Soil Conservation Research Programme, Research Report 37. Herweg,K.andStillhardt,B.1999.TheVariabilityofSoilErosioninthe Highlands of Ethiopia and Eritrea. Average and Extreme Erosion Patterns. UniversityofBerne,Switzerland:SoilConservationResearch Programme, Research Report 42. 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University of Berne,Switzerland:SoilConservationResearchProject,Research Report 15. Krger,H.-J.etal.1997.InventoryofIndigenousSoilandWaterConservation MeasuresonSelectedSitesintheEthiopianHighlands.Universityof Berne,Switzerland:SoilConservationResearchProgramme, Research Report 34. Ludi,E.1997.HouseholdandCommunalStrategies:Small-scaleFarming FamiliesandTheirOptionsforSelf-improvement.UniversityofBerne, Switzerland:SoilConservationResearchProgramme,Research Report 30. MillionAlemayehu.1992.TheEffectofTraditionalDitchesonSoilErosionand Production:OnFarmTrialsinWesternGojam,DegaDamotAwraja. University of Berne, Switzerland: Soil Conservation Research Project, Research Report 22. MulugetaTesfaye.1995.AnAssessmentoftheEffectoftheEnvironmental EducationProjectofEthiopiaonTeachersandStudentsEnvironmental Attitudes.UniversityofBerne,Switzerland:SoilConservation Research Programme, Research Report 25. The Agricultural Environment of Dizi, Illubabor, Ethiopia 58Mulugeta Tesfaye et al. 1995. Classroom Testing of the Amharic Book. Learning fromAnjeni:KewdeAnjeniMinYisemal?UniversityofBerne, Switzerland:SoilConservationResearchProgramme,Research Report 26. MulugetaTesfaye.1988.SoilConservationExperimentsonCultivatedLandin theMaybarArea,WelloRegion,Ethiopia.UniversityofBerne, Switzerland: Soil Conservation Research Project, Research Report 16. Ritler, A. 1997. Land Use, Forests and the Landscape of Ethiopia, 1699-1865: An EnquiryintotheHistoricalGeographyofCentral-NorthernEthiopia. UniversityofBerne,Switzerland:SoilConservationResearch Programme, Research Report 38. Schlfli,K.1985.LandUseProductionandLandDistributionintheAgucho Valley,Ethiopia.UniversityofBerne,Switzerland:SoilConservation Research Project, Research Report 11. Speck,H.1983.SoilsoftheRegionalResearchUnits.UniversityofBerne, Switzerland: Soil Conservation Research Project, Research Report 1. Thomas Tolcha. 1991. Aspects of Soil Degradation and Conservation Measures in AguchoCatchment,WesternHarerge.UniversityofBerne, Switzerland: Soil Conservation Research Project, Research Report 19. Tsehai Berhane-Selassie. 1994. Social Survey of the Soil Conservation Areas Dizi, AnjeniandGununo(Ethiopia).UniversityofBerne,Switzerland:Soil Conservation Research Project, Research Report 24. vonGunten,A.B.1993.SoilErosionProcessesinaTwinCatchmentSet-upin GununoArea,Ethiopia.UniversityofBerne,Switzerland:Soil Conservation Research Project, Research Report 23. Weigel, G. 1986a. The Soils of the Maybar Area, Wello RU (Ethiopia). University ofBerne,Switzerland:SoilConservationResearchProject,Research Report 7. Weigel,G.1986b.TheSoilsoftheGununoArea,SidamoRU(Ethiopia). University of Berne, Switzerland: Soil Conservation Research Project, Research Report 8. 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