Soils and land use in the Tigray highlands (Northern Ethiopia)

Land use in a 208 ha representative catchment in the Tigray Highlands, Dogu'a Tembien district in Northern Ethiopia was studied in relation to soil geography. Typical soils are Vertisols, Vertic Cambisols, Cumulic Regosols, Calcaric Regosols and Phaeozems. Patterns of land use vary greatly within the catchment and results from χ²‐tests showed strong associations (p < 0·001) between soil type and land use and crop production system. There is a strong association between cropland and colluvium high in basaltic content because the most fertile soils, such as Vertisols and Vertic Cambisols, have developed on this material. Preference is for autochthonous soils on in situ parent material, irrespective of the rock type, to be put under rangeland. Land use by smallholders in Dogu'a Tembien appears to be the result primarily of the interaction between environmental and social factors. Copyright © 2007 John Wiley & Sons, Ltd.     

Sediment‐bound nutrient export from micro‐dam catchments in Northern Ethiopia

The losses in soil nutrients (nitrogen (N), available phosphorus (P_av), organic carbon (OC), potassium (K), calcium (Ca) and magnesium (Mg)) in the catchment and the storage in the reservoir as a result of sediment delivery were assessed in 13 catchments/reservoirs in Tigray, Northern Ethiopia. This specifically dealt with factors controlling the losses, the fertility status of the deposited sediment, the nutrient export (NE) rates and associated costs. Enrichment ratio (ER) values >1 were observed for the plant nutrients and the finer soil fractions. The high ER is associated with the preferential transport of nutrients bound to finer soil fractions and the parent material dissolution and its transport via runoff. However, the fertility status of the deposited sediment is not sufficient by itself to support a sustainable crop growth and hence external addition is necessary, mainly for N and P_av fertilizer. Generally, rates of NE were high. The high OC export on the other hand dictates the potential of reservoir sediments for OC sequestration. The cost price of loss of only N and P_av, eroded from the catchment slopes, was estimated at €34·2 million (Euros) in March 2006 for the Tigray. Pity enough, policy makers and beneficiaries do not realize the magnitude of the problem, which forms a major threat for the crop production in the country. Therefore, it is important not only to make the public aware of the problem but also of implementing integrated soil fertility management practices. Copyright © 2007 John Wiley & Sons, Ltd.     

Farmers' perspectives of rodent damage and management from the highlands of Tigray,Northern Ethiopian

A farmers' knowledge, attitude and practice (KAP) survey was conducted in the highlands of Tigray, northern Ethiopia, to better understand rodent damage and rodent management from the farmers' perspective. Farmers (n = 191) from Dogu'a Temben district, were interviewed using a semi-structured questionnaire. The large majority of the farmers stated that rodents are the main pests in crop fields (92.1%) and storage (88.5%). The farmers (64.2%) reported they experienced 100–500 kg ha⁻¹ damage in crop fields, which is equivalent to 8.9–44.7% loss in annual production. There was some overlap between the most common crops grown in the highlands and the most common crops susceptible to rodent attack. Farmers identified barley as the crop most susceptible to rodent attack (76.4%) and the booting stage as the crop developmental stage with the highest rodent abundance and damage. Rodenticide application was the most commonly practiced management strategy in crop fields (51.8%); in storage, farmers mainly keep domestic cats around granaries (80.6%). We recommend a reduction in reliance on chemical rodenticide in crop fields and a shift to a more sustainable rodent management approach to reduce rodent numbers and damage.     

Feeding Acacia etbaica and Dichrostachys cinerea fruits to smallholder goats in northern Ethiopia improves their performance during the dry season

Acacia etbaica Schweinf. and Dichrostachys cinerea (L.) Wight et Arn. are among the common woody browse plants that naturally grow in many arid and semi-arid rangelands in sub Saharan Africa. An experiment was conducted to compare the voluntary dry matter intake, body weight gain, nitrogen balance, carcass composition and sensory attributes of goats supplemented with different levels of A. etbaica and D. cinerea fruits. Average initial body weight of the goats was 20.4 kg (± 0.8SE) and received one of the following fruit supplementation regimes for 120 days (on body weight basis, n = 4 goats per group): (1) Control, no supplement; (2) 0.5% of A. etbaica; (3) 0.5% of D. cinerea; (4) 1.0% of A. etbaica; (5) 1.0% of D. cinerea; (6) 1.5% of A. etbaica; (7) 1.5% of D. cinerea. All groups were allowed to graze/browse during the day. Compared to A. etbaica, D. cinerea fruits contained higher amounts of crude protein (182 vs 135 g/kg DM), metabolizable energy (11 vs 8.4 MJ/kg DM), and in vitro dry matter digestibility coefficient (0.7 vs 0.6). The concentrations of acid detergent fiber (ADF), sulphuric acid solubulized lignin, and tannin (soluble and condensed) were lower (P < 0.05) in D. cinerea than in A. etbaica fruits. A. etbaica fruits, however, contained higher amounts of Na, K, Fe, and Zn concentrations than D. cinerea fruits. Dry matter intake was markedly higher in supplemented groups than in the control group without supplement. Similarly, body weight gain in the control group was negative and lower (P < 0.05) than any of the supplemented groups. During the course of the experimental period (120 days) the group placed in the 1.5% D. cinerea fruit diet gained 2.6 kg whereas the control group lost 2.0 kg. Thus, the difference between these two groups was 4.6 kg, which suggests about 22.5% increment of the goats' initial body weight. N retention was negative for the control group and varied little among the remaining treatment groups. Dressing percent increased with increased level of either type of fruit supplement, the highest (51.8%) being achieved at the 1.5% D. cinerea level. There was no difference in bone tissue across treatment groups. D. cinerea fruit intake also resulted in juicy/watery flavor and tender carcass. D. cinerea fruits appeared to have no adverse effects when included at the highest level (1.5%) and could be collected and stored as dry season supplement to smallholder goats. This study shows that poor farmers can increase goat performance substantially through supplement feeding with wild fruits. Areas in Ethiopia originally set aside for provision of ecological services and biodiversity protection can also be used for wild fruit production and feeding of small stock. The effect of increasing D. cinerea fruits above the 1.5% body weight level should be a focus of future investigation. Further work on deactivation mechanism of tannins is required for A. etbaica fruits included at levels higher than 1.0%.     

Soil and water conservation in Tigray (Northern Ethiopia): the traditional dagat technique and its integration with introduced techniques

Between the cultivated fields in the highlands of Tigray, one finds, besides the recently introduced stone bunds, many lynchets, with a height ranging from 0·3–3 m. Grasses occupy the riser and a more or less large strip on the shoulder. Traditionally, farmers established an untilled strip of about 2 m wide at the lower plot limit. This grass strip reduced runoff velocity, allowed for water to infiltrate and trapped sediment. Year after year, these lynchets, locally called dagat, continued to grow. In this study, the dagat technique is characterized and its evolution and reasons for partial destruction are outlined. Stereoscopic aerial photo analysis shows for the study area near Hagere Selam (13 °39′N, 39 °10′E, 2650 m a.s.l.) that 20·7 per cent of the major dagats (more than 1 metre high) have disappeared between 1974 and 1994. These lynchets, however, remain an important linear element in the landscape (22·7 m ha⁻¹, i.e. their density on cultivated fields is much higher). Of the smaller lynchets, a great proportion has been levelled in order to increase plot surfaces and spread fertile soil over the field. Famines and impoverishment caused the farmers to increase short‐term agricultural production in this way. Since the 1980s, the farmers built stone bunds on most of the cultivated land. Their average length equals 56·1 m ha⁻¹ in the study area. The establishment of stone bunds results in the development of small terraces. Especially during recent years, there is a tendency to integrate the traditional knowledge of dagat with the building of stone bunds. A quantitative assessment of the effectiveness of both techniques must be made. Copyright © 2000 John Wiley & Sons, Ltd.     

Historical landscape photographs for calibration of Landsat land use/cover in the northern Ethiopian highlands

The combined effects of erosive rains, steep slopes and human land use have caused severe land degradation in the Ethiopian Highlands for several thousand years, but since the 1970s, however, land rehabilitation programmes have been established to try to reverse deterioration. In order to characterize and quantify the transformations in the north Ethiopian Highlands, a study was carried out over 8884 km² of the Tigray Highlands of northern Ethiopia. Using Landsat Multispectral Scanner and later Thematic Mapper imagery (1972, 1984/1986 and 2000), historical terrestrial photographs (1974–1975) and fieldwork (2008), we prepared land use and cover maps. For assessing the use of the historical terrestrial photographs, Landsat images from 1972 were classified using two different methods, namely conventional change detection (image differencing) and ground truthing (using the historical photographs of 1974–1975). Results show that the use of terrestrial photographs is promising, as the classification accuracy based on this method (Kappa coefficient 0·54) is better than the classification accuracy of the method based on image differencing (Kappa coefficient 0·46). Major land use and cover changes indicate the following: (1) a gradual but significant decline in bare ground (32 per cent in 1972 to 8 per cent in 2000); (2) a significant increase of bushland (25 to 43 per cent) and total forest area (including eucalypt plantations, 2·6 to 6·3 per cent); and (3) creation of numerous lakes and ponds. The dominant change trajectory (27 per cent of the study area) indicates a gradual or recent vegetation increase. These changes can be linked to the population growth and the introduction of land rehabilitation initiatives, complemented by growing awareness of land holders. Copyright © 2012 John Wiley & Sons, Ltd.     

Echinococcosis/hydatidosis: its prevalence,economic and public health significance in Tigray region,North Ethiopia

A cross sectional study was carried out to assess the prevalence, economic and public health significance of echinococcosis/hydatidosis in Tigray Regional State, north Ethiopia. Out of 18 stray dogs euthanized and examined, three of them were found harboring the adult parasite Echinococcus granulosus in their small intestine. From 5,194 cattle examined at slaughter houses, 1146 (22.1%) of them were found harboring hydatid cyst. The majority of the infected cattle had hydatid cyst in both liver and lungs. The hydatid cyst infection in the lung, liver, kidney, heart and spleen were found to be 13%, 8.1%, 0.5%, 0.4%, and 0.1%, respectively. The estimated total annual loss from bovine hydatidosis due to offal condemnation (lungs and liver) and carcass weight loss was 25,608 Ethiopian (Eth.) Birr. The present human hydatidosis survey conducted in all six zonal hospitals of Tigray Regional State disclosed one active clinical case in Mekelle hospital during the study period. While, the retrospective data analyses of the six zonal hospitals indicated that eight cases of human hydatidosis were diagnosed since 2000. Thus echinococcosis/hydatidosis is considerably prevalent disease in cattle and it is a serious public health concern in Tigray region.     

Changes in soil organic carbon stocks and soil quality: land-use system effects in northern Ethiopia

Abstract

In Tigray, Ethiopia, land degradation is a dominant environmental problem and hence the regional government has undertaken restoration measures on degraded soils since 1991. The present study was aimed to assess the impact of land uses and soil management practices on soil properties, and consequently on soil quality of degraded soils. The catchments selected were Maileba and Gum Selassa, and land uses included cultivated (CL), grazing (GL), plantation (PA) and area exclosure (AE). Replicated soil samples were collected from topsoil and profiles of four land-use types in both catchments. Soils in area exclosure showed higher soil organic carbon (SOC), total N and extractable K than grazing land, cultivated land and plantation area mainly at 0–40 cm soil depth. Estimated soil organic carbon stock at Maileba in 0–40 cm depth varied between 54 to 74 Mg C ha^?1, being lowest in cultivated land and highest in area exclosure, and the soil organic carbon stock in area exclosure represents 63% of total carbon stock stored in the profile. Soil organic carbon stock (0–40 cm) at Gum Selassa ranged between 33 to 38 Mg C ha^?1, being higher in cultivated land and lower in plantation area. Soil quality index (SQI) of area exclosure (0.794) at Maileba and cultivated land (0.721) at Gum Selassa scored highest among all land uses, and the order was area exclosure>grazing land>plantation area>cultivated land at Maileba and cultivated land>grazing land>plantation area at Gum Selassa, highlighting the effectiveness of area exclosure in restoring soil quality of degraded soils.     

Soil landscapes,land cover change and erosion features of the Central Plateau region of Tigrai,Ethiopia: Photo-monitoring with an interval of 30 years

Human land use of the Tigray landscape (north Ethiopia) can be traced back for at least 3000 years and is recognizably very complex, but in the past half-century there have been multiple narratives on environmental change in the Northern Ethiopian Highlands in which statements such as “the forest and soil resources in Tigray are dwindling at unprecedented rates” are common. In an attempt to provide an objective assessment, we made a semi-quantitative analysis of observed changes in the environment of the central Tigray plateau, between 1975 and 2006, and its impact on soil erosion. The first part of this period saw strong degradation, caused by a combination of drought, impoverishment, poor land husbandry and war; but over the whole period intense rehabilitation activities have been high on the agenda. To study these changes, two sets of 51 landscape photographs have been used. The older photo-set was taken in 1975 by R.N. Munro during the Tigrai Rural Development Study; locations were revisited in 2006 by J. Nyssen and colleagues, when a new set of photographs was made at the same locations and with the same aspect. Based on longstanding experience in soil erosion and landscape analysis worldwide and in Ethiopia, the time-lapsed photographs were rated for visible erosion, land cover and protective measures. We present a quantitative evaluation of the change of soil loss by sheet and rill erosion, involving the Universal Soil Loss Equation (USLE) and particularly the changes in the C (cover) and the P (management) factors. This allowed assessing soil loss in 2006 as a percentage of the 1975 situation. Both the landscape and land unit analysis show that the situation for natural resources has improved (and locally strongly improved) since 1974. The rehabilitation is due both to improved vegetation cover and to physical conservation structures. The USLE application indicates that in terms of a whole landscape the current average soil loss would be at around 68% of its 1975 rate. Exceptionally, degradation is still ongoing around Desa'a forest and some other remnant forests, and conservation should be strongly implemented too in these forests. On average, gullies have expanded slightly since 1975, but these incisions appear to have originated in the drought years of the 1980s. This photo-monitoring analysis invalidates hypotheses on (a) irreversibility of land degradation in Tigray; and (b) futility of Soil and Water Conservation (SWC) programmes. The study demonstrates that (a) land management has become an inherent part of the farming system in Tigray, and (b) that the authorities and NGOs are on the right track when promoting SWC.     

Impact of exclosures on wood biomass production and fuelwood supply in northern Ethiopia

In the Ethiopian highlands, communal grazing lands are one of the major land uses, and are source of livelihood for the rural people. Free and uncontrolled grazing in the communal grazing lands is the dominant grazing system. The traditional uncontrolled and free grazing system has caused severe degradation of the grazing lands. As a result, communities have started to establish exclosures and support the restoration of degraded communal grazing lands. Studies have shown that exclosures are effective to restoring degraded communal grazing lands and improving ecosystem services. However, studies that investigate the changes in aboveground biomass following the establishment of exclosures and compare it with fuelwood demand of the beneficiaries in our study area is lacking. Therefore, our study aimed at:(1) quantifying yearly biomass accumulation in exclosures and compare it to fuelwood demand of households that manage the exclosures;(2) assessing household energy sources and their consumption levels. To monitor changes in biomass production with over time, replicated(n = 3) 5 and10 year-old exclosures were sampled. To investigate fuelwood sources and consumption patterns, household surveys, key informant interviews and focus group discussion were conducted. Our results demonstrated that total biomass production increased with exclosure age. In both exclosure, biomass production from Vachellia etbaica was significantly(p \ 0.05) greater than that from Euclea.racemosa. Average daily fuelwood consumption per person was(0.63 ± 0.2) kg day^-1. This means that the total biomass(27.5 Mg year^-1) obtained from 114.6 ha of exclosures covers only 9.4% of yearly fuelwood demand of the residents who manage the sampled exclosures. Nearly all respondents(95%) confirmed that they travel more than10 km day^-1 to gather fuelwood from surrounding degraded forest patches. We recommend plantings of fast growing native tree species within exclosures and around homesteads to provide a sustainable fuelwood supply and using improved stoves to address the problem of fuelwood shortage. District agricultural offices could provide seedlings of native plant species, while communities provide unpaid labour for planting and managing plantations.