The Successful Soil Conservation Methods in Ethiopia: A Review

: Soil conservation is the protection of fertile top soil from erosion by wind and water and the replacement of nutrient in the soil and it is the combination of the appropriate land use and a management practice that promotes the productive and sustainable use of erosion and other forms of land degradation. It has become an integral part of land use and receives support within a social and economic environment which is conductive to the maintenance and improvement of soil capital. The grass strips, bench terraces and fanyajuu reduced soil loss by 40, 76 and 88%, respectively, compared to the land without those structures. In the Anjeni area of Ethiopia, graded soil bund reduced soil loss by 40% as compared with untreated plots. An annual soil loss from crop lands with level soil bunds reduced by 51% when compared to the control plot. In DebreMewi, Ethiopia, Stone bunds and soil bund reduced soil loss by 72.9 and 83.7% respectively as compared to non-treated land. In northern Ethiopia, especially in Tigray, Stone bund is effective in reducing soil loss by 68% particularly at its early age. In the central highlands of Ethiopia, the soil bund reduced the yield of barley by 7% when the spaces occupied by the structures are taken into account and otherwise increased yield by 1.7%.Agro-forestry is also one of the practices mainly used in Ethiopia at the low land areas where Mango ( Mangifera indica L.) is well integrated with the cultivated crops and considered as an important component of the farm. The vetiver system reduces soil loss from farm land by 90% and reduces rainfall runoff by 70%. Rotating


INTRODUCTION
developing nations like Ethiopia has resulted in the un Agriculture is the main sector of the Ethiopian fundamental natural resources to support life on earth.economy and contributes approximately 42% to the gross Soil is finite and non-renewable natural resource which domestic product (GDP) and employs over 80% of the takes between 200 and 1000 years for 2.5 cm of topsoil population [1][2][3].Despite its role, agricultural production formation under cropland condition [6] is constrained by high climate variability where rainfall As a core component of land resources, soil is the distribution is extremely uneven both spatially and source of many ecosystem services essential to humans temporally and this has negative implications for the and the environment [7].It is the base to support primary livelihoods of people [4].Drought frequently results in production through organic matter and nutrient cycling, crop failure, while high rainfall intensities result in low control of pests and diseases; decontamination of the infiltration and high runoff causing enhanced soil erosion environment and provision of ecosystem services [8].and land degradation.The combination of the rapid Soil also plays a major role in global climate processes growing world's population, slow economic growth and through regulation of carbon dioxide (CO ), nitrous oxide limited extent of natural resources, especially in many (N O) and methane (CH ) emissions [9].Global estimates, sustainability use of natural resources [5].Soil is one of 2 2 4 however, indicate that human pressures on soil resources deicide on the benefits of SWC technologies and actively are reaching critical limits [9] and soil is becoming involved in the implementation and maintenance vulnerable to various forms of depletions, such as soil processes [23].The decisions of farmers to use and erosion, soil fertility decline and associated changes in manage natural resources highly depend on their soil physical and chemical properties.Soil erosion by perception of the landscape [15].Indeed, farmers can water is the most severe and widespread that occupies modify the technologies to their own real situations [22].56% [10].
And threats not only to agricultural production but The average annual rate of soil loss in Ethiopia is also to the economy, as the countries' economies depend estimated to be 12 tons/hectare/year and can be even on agricultures.Soil erosion creates sever limitations to higher on steep slopes (greater than 300 tons/hectare/year sustainable agricultural land uses, as it reduces on farm or about 250 mm/year) where vegetation cover is scant soil productivity and cause food insecurity [24].Erosion [11].Alemayehu [12] also reported the same result.Soil results in the degradation of soil productivity in a number erosion is very severe problem in highlands of Ethiopia, of ways.It reduces the efficiency of plant nutrients use, especially on cultivated fields of northern and central high damages seeding, decreases plants roots depth, reduces lands of Ethiopia and erosion on cultivated lands the soil water holding Capacity, decreases its averagely estimates 42 tons per hectare per year on permeability, increase run off and reduces its infiltrations currently cultivated lands [13].
rates [25].In addition the loss of nutrients alone resulting According to Tegegn [14], Soil Erosion is the removal from soil erosion has an estimated cost to the united of top soil faster than the soil forming process to replaces stated up to$20 Billion years.People were already aware it, due to natural, animals and human activities: of the negative consequences of soil erosion on overgrazing, over cultivation, forest clearing and agricultural production and the environment centuries ago mechanized farming.As a result, soil erosion is the most [26].As a result, indigenous soil and water conservation immediate environmental problem facing the nation at practices have existed for many years in some areas of present time.Soil erosion, principally caused by over Ethiopia [27,28].For instance, the United Nations grazing, continuous cultivation, deforestation and remove Educational, Scientific and Cultural organization of crop residue from the field, highly undermines the role (UNESCO) has registered the terraces of the Konso of agriculture to alleviate poverty and food insecurity in people of Southern Ethiopia as one of the world heritage whole parts of Ethiopia.The estimated annual soil loss in [26].Soil conservation refers to the protection of fertile Ethiopia due to erosion is 1.5 billion tons, of which 50% top soil from erosion by wind and water and the occurs in cropland [15].This is very serious problem replacement of nutrient in the soil by means of cover compared to the estimated soil formation rate of less than crops, terracing, contour farming crop rotation etc. SWC 2t/ha/year [16].Its severity is being pronounced in the can be defined as the combination of the appropriate land Northern highland areas of the country [17,18] which has use and management practices that promotes the been characterized by steep slopes, intensive rainfall, productive and sustainable use of erosion and other sparse vegetation, high population and livestock forms of land degradation.Generally, soil-water densities [19].
conservation includes all forms of human action to It is clear that soils with low fertility are unable to prevent and treat soil degradation [29].As Tibabe and allow sufficient crop cover to sustain life.Erosion and low Mitiku, (2002) cited in [30], the aim of soil-water humus content of such soil decrease infiltration and conservation is to facilitate optimum level of production moisture holding capacity of the soil.These all quest for from a given area of land while keeping soil loss below a the importance of soil conservation measures.Thus, it is critical value and protections of the life supporting increasingly recognized that adequate conservation of capacity of soils such as soil quality, soil depth , soil soil resources is a precondition for sustainable rural structure, water holding capacity and soil productivity.development strategies particularly in the highlands of Ethiopia [20].A large number of conservation, Successful Methods of Soil Conservations in Ethiopia: rehabilitation and afforestation campaigns were Soil conservation has become an integral part of land use undertaken through Food-For-Work (FFW) programs.
and receives support within a social and economic Nevertheless, most efforts of soil conservations have not environment which is conductive to the maintenance and been widespread and didn't bring signi?cant changes as improvement of soil capital [31].The ultimate aim of soil expected [21,22].Effective protection and conservation of conservation is to obtain the maximum sustained level of SWC can be realized only when farmers accept and production for a given area of land whilst maintaining soil , where the grasses/trees are harvested on a regular basis through a cut-and-carry system; and (d) check dams constructed across gullies (d1 is before (2012) and d2 is after (2013) intervention).Source: Nigussie et al. [15] loss below a threshold level which, theoretically, permits highlands of Ethiopia, when compared to the non-terraced the natural rate of soil formation to keep pace with the rate land, the absolute soil loss from the terraced site was still of soil erosion [32].There are two technical means for high (24 tha year ) [42] and required certain achieving these principles of soil and water conservation: improvements/support measures to reduce absolute soil the barrier approach and cover approach [33].
loss to are commended tolerable range [33,43].A conservation technique may be regarded as The SWC reduced soil loss by at least 61% in the successful if it reduces the rate of soil loss to less than Tigray region [44] and in Somali region [45] as compared 20% of the rate without conservation and to less than with untreated sites.The effect of SWC structures is 10 t ha year-1 which is the commonly accepted as a observed after some years of the structure being built.
1 "tolerable "rate of erosion [33].Tenge et al. [34] reported In three years old structures, Teshome et al. [37] that the grass strips, bench terraces and fanyajuu reduced observed 10 and 15% yield increments in DebreMewi and soil loss by 40, 76 and 88%, respectively, compared to the Anjeni (Ethiopia) watersheds, respectively, when land without those structures.Also, Herweg and Ludi [35] compared to the yield before constructing those reported that in the Anjeni area of Ethiopia, graded soil structures (fanyajuu, soil bunds).Regarding this, bund reduced soil loss by 40% as compared with Wolka et al. [39] reported that 79.3% of the interviewed untreated plots.According to Tesfaye [36], the annual farmers perceived the increment of yield after 2 years of soil loss from croplands with level soil bunds reduced by SWC structures (the soil bund and stone bunds) were put 51% when compared to the control plot.In DebreMewi, in place .Herweg and Ludi [35] reported that, a 4-50% Ethiopia [36].Stone bunds and soil bund reduced soil decline in yield during the first 3-5 after the construction loss by 72.9 and 83.7% respectively as compared to of SWCmeasures due to water logging problem; this was non-treated land [37].The conservation techniques followed by subsequent yield increases ranging from include both the new and traditional techniques such as 4-15% [35]; Nyssen et al. [27] found that after a few years traditional bunds and the newly introduced stone bund of its construction, stone bunds increased cereal and terracing, check dams, closures and plantations.It is a teff yields by 8 and 11% respectively, even by considering combination of all methods of management and land uses the area lost due to the conservation structures.that safe guard the soil against deterioration by natural or Indigenous stone bunds (kab) have increased man-induced factors [38].
sorghum yield by 56-75% compared to other non-terraced Stone Bunds: These are barriers of stones placed at that stone bunds, soil bunds and grass strips have robust regular intervals along the contour.They have been used and positive out puts on crops in the low rain fall areas of for generations in Ethiopia where they are locally known the Blue Nile basin in Ethiopia and high risk reducing as "dhagaa" and in some parts of South Africa.The size effects in high rain fall areas. .This study indicated that of the stone bunds varies between 0.5-2m and may be 5 to grass strips have highest production elasticity among 10m apart, depending on the availability of stones and the SWC technologies in their low rain fall areas.In these topography.Laying stone bunds in fields is a well-known areas soil bunds have risk reducing effects.The stone technique to check runoff and to control erosion and is bunds aged 3-21 years increased crop yield by 0.58-0.65 the most widely practiced technique by farmers [40].

Stone bunds retain or slow down run off and hence
Stone bunds contribute to agricultural productivity control erosion.They also allow the accumulation of soil, due to its moisture conserving role.Results of the which may be redistributed after the bunds are dismantled analyses based on multiple plot observations per [41].
household indicated agricultural plots with stone bunds In northern Ethiopia, especially in Tigray, Stone bund are more productive than those without it in dry areas but is effective in reducing soil loss by 68% particularly at its not in the high rain fall areas of northern Ethiopia [48].early age.Its effectiveness decreases as the depression on the upslope side of the bunds accumulates sediment Terracing: Yeshambel, reported that, in Konso Cultural and thus requires frequent maintenance to sustain the Landscape is characterized by extensive dry stone effectiveness.Another report in the Tigray region found terraces which witnesses hundreds of years of persistent stone bunds can trap 64% of the soil moved by water human struggle to harness the hard, dry and rocky erosion.Even though soil bunds reduced soil loss by environment, which has resulted in the beautifully 47% in experimental site established in the central outlined rows of dry stone terrace.The terraces retain the soil from erosion, collect maximum water and discharge barley by 7% when the spaces occupied by the structures the excess and create terrace saddles that are used for are taken into account and otherwise increased yield by agriculture.The terraces are the main features of the 1.7% [42].Possible biological measures such as Konso landscape and the hills are contoured by the dry enclosures, tree and shrub planting and management, stone terraces that could reach at some places up to 5 agroforestry, strengthening the structures with grass or meter high.The dry stone walled towns (Paleta) of the shrubs etc., should be given priority due to their multiple Konso are located on high hills selected for their strategic and sustaining roles.Many case studies indicated that and defensive advantage.These towns are circled by, biological measures and soil fertility management could between one and six rounds of dry stone defensive walls, improve effectiveness of the structures and soil fertility built using locally available rock [20].Habtamu [50] [42].reported that, Stone terraces were constructed in areas where construction material like stone is available.
Agroforestry System: A system called "Agro forestry" His study was focused on the conservation measure of has been widely promoted in the tropics in recent years.soil and water practiced highly over farmland of Bole Here tree and field crops are grown together in the same Becho and Iluna-egu-Kura village of the north Showa field.The trees are often grown in narrow strips, often on (Oromia Region, Ethiopia).
the contour and are usually cut at different times so that Soil Bunds: Soil bunds are constructed on agricultural crops.The trees may be either fruit trees or trees, which and non-agricultural land with the aim of arresting soil have the ability to trap nitrogen from the atmosphere and erosion and improving the soil moisture profile [51].
return it to the soil where it can be used by other plants.The main aim of soil bund is by conserving the soil and A good ground cover of grasses, shrubs and/or leaf litter harvesting the water, reduces and stops erosion and is needed if the trees are to effectively control water increases water holding capacity of the soil so as to erosion.Agro-forestry is also one of the practices mainly enhance crop yield.Soil bunds also called fanyachini in at the low land areas in the Woreda where Mango Swahili is channel terrace structure constructed across the (Mangifera indica L.) is well integrated with the sloping arable land surface to intercept surface runoff.cultivated crops and considered as an important These structures break up a long slope into a series of component of the farm.The best example is Moringa short ones, each channel collecting the runoff from a stenopetala (locally also called to be Moringa) which has definite area of the slope above it [52].In the central several purposes; used for shade, main diet, medicine.highlands of Ethiopia, the soil bund reduced the yield of Other tree species in Konso are: Juniperus procera, they do not provide shade that would affect the field Euphorbia spp.Terminalia browenii, Olea africana, water availability to crops and increasing the soils water Ficussori, Cordia africana, Sterculia africana, retention capacity [57].Until the recent years returning Accia abysinica.Among these, Juniperus procera has a crop residues to soil were not common practices for most high significance in Konso's rituals.Thus, it seems that farmers, who prefer to use for livestock feed, fuel and in addition to trees role for indigenous soil conservation construction materials or to burn or remove from the fields practices in agro forestry form has strong attachment the [54].This finding was found to be in agreement with the society cultural practices [20].
works [9], reported that, mulches are materials placed on Agro forestry is also a valuable traditional practice the soil surface to protect it against raindrop impact and which plays an important role in maintaining ecological erosion and to enhance its fertility.stability.Trees used in agro-forestry system can also Another methods of soil conservation is Mulching provide a variety of services such as being a form of which the covering of the soil with crop residues such as saving and investment, protection from wind, employment straw, maize or sorghum stalks or standing stubble.opportunity, increased amount of water for plant growth, The cover protects the soil from raindrop impact and improved seasonal availability of water, protection of soil reduces the velocity of runoff.Maintaining crop residues from erosion and loss of nutrients, restoration of or mulches on the farm controls effectively soil erosion degraded soils and improvement of soil moisture and and has considerable potential for the restoration and fertility, maintenance or increase in species and habitat maintenance of soil fertility.Mulching is one of the most diversity and improved conditions for natural effective methods to minimize erosion.A crop residue regeneration of most desirable species [53].
covering the ground intercept raindrop impact, preventing Grass Strip: Grass strip is the biological land the infiltration rate.It also encourages insects and worms management practice in Ethiopia which is being practiced to take holes into the ground, thus increasing the by farmers in their fields by planting vetivar and native permeability of the soil [1].Most farmers in Konsoworeda grasses along the contour at the top and in between the are using surface mulches on their fields, thus providing farmland.Besides serving as fodder for the cattle, also a protective cover at a time when crop cover is not impacts soil.The barriers were usually of grasses, which present.Some farmers left crop residue while others used has been planted or left to grow naturally in narrow strips by branches.The benefit of protective covering was along the contour at intervals across the slope of a field.
widely appreciated, as was the improved infiltration rate When planted as a contour hedge it acts as a continuous afforded by the techniques and reduced evaporation rate.filtering system that slow down run off and collects soil Further stated objective is the addition of nutrients to the sediments at the hedge faces [54].Since Vetiver grass root soil through the decomposition of the organic matter.system grows more vertically than horizontally, it does However, the density of mulch viewed in many fields was not compete for more space with crops planted in the below the level required to be most effective as protective field.Alemu Mekonnen indicated that the grass can be cover since the use of residence as animal food was effectively used on the existing soil bunds, contours witnessed in many households of the area [20].without any physical structure, waterways and cutoff drains, around ponds reservoirs, irrigation and drainage Crop Rotation: Crop rotation is a practice of growing canals, micro basin and check dams [11].The vetiver different crops one after another on the same piece of system reduces soil loss from farm land by 90% and land, season after season or year after year.It is a reduces rainfall runoff by 70% [55].In addition, the leaf of valuable traditional practice, which plays an important role vetiver grass is used for fodder, roof thatching, making in maintaining ecological stability and improving ropes, mats, hats, baskets, mattress stuffing, making agricultural productivity.If the same crop is grown on a brooms and others.It is used also as insect and rodent piece of land year after year, the soil nutrient depletes repellents [56].
sharply and as a result yield decreases.Nevertheless, if Leaving Crop Residues and Mulching: Residue and the decline in crop yields is minimized [54].The use of management is an act of leaving crop residue on the field crop rotation is widespread phenomena in the after harvest mainly for the purpose of animal feed, fuel Konsoworeda where maize, ground nut and sorghum and construction materials.Despite its uses as animal grown rotationally.Crop rotation is used by the farmers feed, fuel and construction purpose crop residues are important for different reasons including soil fertility, very important for crop land improvements by enhancing thereby improved crop yield.The farmers of the area splash erosion, slow down the water flows and increases different crops are rotated, the depletion of soil nutrient know that as of the scientific method improved soil water erosion is the most important land degradation fertility can be achieved by alternating high residue process that affects the physical and chemical properties producing crops with the growing low residue producing of soil resulting in on-site nutrient loss and off-site soil crops [20].
sedimentation.Crop differs in their effect on soil.Some crops restore Soil conservation has become an integral part of land or build fertility of the soil, while others deplete its use and receives support within a social and economic fertility.For instance, legumes fix atmospheric nitrogen environment which is conductive to the maintenance and and hence enrich soil fertility.Forage legumes and improvement of soil capital.The ultimate aim of soil grasses provide good ground cover that protects soil conservation is to obtain the maximum sustained level of erosion and enriches the soil with organic matter, which production for a given area of land whilst maintaining soil in turn improves the structure and biological activities.
loss below a threshold level which, theoretically, permits Cereals such as sorghum and maize deplete soil fertility.
the natural rate of soil formation to keep pace with the rate Crop rotation, in addition to fertility restoration and soil of soil erosion.It is clear that soils with low fertility are and water conservation use, is a traditional cropping unable to allow sufficient crop cover to sustain life.practice for controlling diseases, pest and weed Erosion and low humus content of such soil decrease infestation.Different crops are not equally susceptible to infiltration and moisture holding capacity of the soil.pests or diseases.Growing the same crop every year leads These all quest for the importance of soil conservation to build up of pests and diseases in the field, which attack measures.Thus, it is increasingly recognized that that particular crop [54].
adequate conservation of soil resources is a precondition Crop rotation maintains or improves productivity as for sustainable rural development strategies particularly a result of improved fertility of the land and reduced in the highlands of Ethiopia.Generally, Practicing pest/diseases problems.Different crops vary in their indigenous and introduced soil and water conservation response to different pests and diseases.Some crop are practices such as soil bunds, stone bunds, agroforestry, resistant to some pest and disease including weeds, vetiver grass, crop rotation, mulching/residue while others are susceptible.Sorghum is more susceptible management, hillside terraces and grass strip or to the parasitic weed (striga) than leguminous crop hedgerows etc. to either divert runoff into safe channels, (e.g.chickpea)and oil crop (Noug).Therefore, it is such as grassed water ways, or reduce it by promoting advisable to grow legumes or oil crops after sorghum than infiltration is the ultimate aim of soil conservation to growing sorghum after sorghum or millet after sorghum obtain the maximum sustained level of production for a and vice-versa, MoFED [1].For Teklu and Gezahegn, the given area of land whilst maintaining soil loss below a major cereals, after legumes or oil crops are rotated mainly threshold level which, theoretically, permits the natural for soil fertility maintenance, weed and disease control rate of soil formation to keep pace with the rate of soil [58]. erosion.

Fig. 8 :Fig. 9 :Fig. 10 :
Fig. 8: Soil Bunds in Danech (Siliti Woreda, SNNPRS)Source: Mushir and Kedru[49] is one of fundamental natural resources to 1. MoFED (Ministry of Finance and Economic support life on earth.It is finite and non-renewable natural Development), 2010.Growth and transformation plan resource which takes between 200 and 1000 years for 2010/11-2014/15.Volume I: Main text.Addis Ababa, 2.5 cm of topsoil formation under cropland condition.Ethiopia: Ministry of Finance and Economic Degradation due to soil erosion and nutrient depletion Development (MoFED), Federal Democratic Republic are the most challenging environmental problems in of Ethiopia.Ethiopia.The Ethiopian highlands have been experiencing 2. Diao, X., 2010.Economic importance of agriculture declining soil fertility and severe soil erosion due to for sustainable development and poverty reduction: intensive farming on steep and fragile land.The The case study of Ethiopia.Paper presented at the population in the rural areas is increasing and more food OECD Global Forum on Agriculture: Policies for is required to feed this population.On the other hand the Agricultural Development, Poverty Reduction and land size used by farmers is reducing.These situations Food Security, Organisation for Economic Coforced the farmers to use the land intensively throughout operation and Development (OECD) Headquarters, the year that has resulted in soil degradation.In Ethiopia, Paris, France.