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The study aimed at investigating effects of lime and mineral P fertilizers on P uptake and growth of maize (Zea mays subsp.) in greenhouse pot experiment. Combination of four P rates and four lime rates were applied to four highly acidic soil samples and the soils were incubated for a total of 112 days after which maize (Zea mays subsp.) was planted. The maize plants were harvested for analysis after 42 days of growth. Control experiments were also included. Available P (Bray I) and pH were significantly increased after incubation. Maximum available P was obtained in the soils that received the highest P rate and optimum lime rate. Levels of exchangeable acidity were significantly decreased in the P and lime treated soils compared to the control experiments. Plant biomasses and P uptake of maize increased significantly (p ≤ 0.001) with application of P and lime compared to the control experiments.

Understanding tempo‐spatial dynamics of land‐use/cover (LULC) and its drivers is instrumental in synthesizing knowledge for informed natural resource management planning and associated decisions. The present study investigates tempo‐spatial LULC changes, their drivers and the associated impacts in three sub‐basins (Zeway, Ketar and Bulbula) in the Central Rift Valley (CRV) of Ethiopia. Satellite imageries of different periods in ArcGIS, field observations, focus group discussions (FGDs) and secondary data were used to analyse the LULC dynamics, their drivers and associated impacts from 1973 to 2014. The overall accuracy of 1973, 2003 and 2014 classification maps was 88.7%, 88.9% and 91.6%, respectively. The analysis results revealed a continuous increase of farmland and town built‐up areas at the expense of grasslands, shrub‐bush land and woodlands. It further indicated area of open irrigated agriculture, increasing from none to 2.61% of the total area. The FGDs demonstrated agricultural land expansion, resettlement and wood extraction were proximate causes of the observed LULC changes. Population increases, changes in land tenure system and decreased farmland productivity were determined to be the underlying causes of the changes. The FGDs further indicated these changes have negatively affected the natural resources. The present study findings indicate the need to reconsider land‐use decision tradeoffs between economic, social and environmental demands, and their implications for other similar areas in Ethiopia and beyond. Quantitative analysis and periodic evaluation of the drivers of such change and the impacts of existing and emerging land‐uses in the face of changing climate is recommended to facilitate sustainable use of the fragile ecosystems in the Ethiopian CRV.

Background Potassium (K) availability depends on exchangeable K and relative amounts of other cations. Yet, the latter has mostly been overlooked. Thus, this study was conducted to evaluate availability and spatial distribution of soil K in Nitisols of Wolaita area, southern Ethiopia, with particular regard to emphasis on assessing the potential for magnesium (Mg)-induced K deficiency. About 789 soil samples were investigated and mapped using ordinary kriging method. Results The result showed that 14.8% of the samples were K-deficient based on exchangeable K rating, whereas the K deficiency due to antagonistic effects of Mg was 54%. The spatial analysis also revealed that 68% of the study area (i.e., 57, 120 ha) has shown Mg-induced K deficiency. The finding is against the long belief that soils of the study area and the country contain sufficient quantity of K. Conclusion The findings of this study imply the need for inclusive approach while assessing the K status of soils and also call for greater attention toward K fertilizer intervention that was not in place in the study area. Nonetheless, further study including fertilizer application rates is suggested.

Background Soil acidity with associated low nutrient availability is one of the major constraints to faba bean (Vicia faba L.) production on Ethiopian highlands. Integrated use of organic and inorganic amendments is believed to reduce soil acidity and improve crop production. Therefore, this field experiment was conducted with the objective of evaluating the effects of lime, mineral P, farmyard manure (FYM), compost and rhizobium in acid soil of Lay Gayint District, northwestern highlands of Ethiopia, in 2016–2017 main cropping season. The experiment comprised twenty sole and combined treatments arranged in a completely randomized block design with three replications. Results Combined application of 8 t FYM ha−1 + 30 kg P ha−1 + 3.6 t lime ha−1 significantly (P

Integrated use of lime with organic and chemical fertilizers is considered as a good approach for sustainable crop production under acidic soils. Vermicompost (VC) and chemical phosphorus (P) fertilizer when used with lime play a vital role in enhancing productivity of acidic soils. Field experiments were conducted for two consecutive cropping seasons of 2015 and 2016 to evaluate the effects of lime, VC and chemical P fertilizer on yield and yield components of maize in Ebantu District, Western highlands of Ethiopia. The experiments were laid out in a randomized complete block design as a factorial combination of two lime rates (0, and 4 t CaCO3 ha-1), three VC rates (0, 2.5 and 5 t VC ha-1) and three chemical P rates (0, 20 and 40 kg P ha-1) which were replicated three times. Relevant crop parameters were measured following standard procedures. Tasseling days (102), silking days (109), highest leaf area index (5.91), plant height (3.48 m), cob length (47.83 cm), number of grain per cob (644) and above ground dry biomass yield (22 t ha-1) were exhibited by 5 t ha-1 VC and 40 kg ha-1 chemical P fertilizer with lime of 0 and 4 t ha-1 while the highest 1000-seed weight (508 g), grain yield (4.87 t ha-1) and harvest index (24%) were obtained at 2.5 t ha-1 VC and 40 kg P ha-1 with lime. Integrated application of organic and chemical fertilizers with lime amended the acidic soils and improved its fertility which in turn increased crop yields. Combined use of VC at 2.5 t ha-1 and chemical P fertilizer at 20 kg ha-1 with lime at 4 t ha-1 is economically optimum and could be recommended for reclaiming soil acidity and improve nutrients for maize as it enhanced grain yield and yield components of maize plant in strongly acidic soils for the two consecutive years pooled together. Key words: Maize yield, lime, Vermicompost (VC), phosphorus (P), integrated application.

The central Ethiopian highlands where most human and livestock populations concentrated have experienced a drastic change in land use and land cover (LULC) of the landscapes. This study was aimed to define the rate and pattern of LULC changes in Dendi-Jeldu hilly-mountainous areas in the central Ethiopia. Aerial photographs of years 1957 and 1995, and Landsat images taken at 1995 and 2014 were used to analyze the historical land use and land cover (LULC) changes. The study covered an area of about 438 km2. The analysis extracted from these remote sensing data revealed that, in 1957, the dominant LULCs were pastureland, cultivated land (cropland) and forestland covering 49, 25 and 20% of the total area, respectively. Remarkable LULC change dominated by cultivated land expansion (now covering 68% of the total area), however, claimed vast areas under pastureland (main), forestland and woodland. Deforestation in particular, would have been greater if Chilimo forest (remnant afro-montane forest) was not under state control. Plantation forestry exclusively dominated by eucalyptus species also showed substantial expansion into pastureland in the period between 1957 and 1995, and cultivated land between 1995 and 2014. In the period 1957 to 2014 cultivated land, plantation land and settlement were increased by 170%, 13,674% and 172% respectively, while pastureland, forestland and woodland declined by 67%, 73% and 100%, respectively. Change from natural habitat (pastureland, forestland and woodland) to other land uses (cultivated, plantation and settlement lands) is likely to have a large impact on biodiversity, land degradation and beyond.

The study examined the impact of deforestation and subsequent cultivation on soil fertility and acidity conditions under varying soil depths. Soil profiles were opened in two adjacent land units, namely forestland and arable land and samples were collected from genetic horizons. Deterioration of soil fertility was observed after deforestation and traditional cultivation. The main aim of deforestation was agricultural expansion. Soil pH consistently decreased with depth in both land units and it was relatively lowest in arable land perhaps due to depletion of organic matter (OM) and decrease in buffering capacity of the soil. The OM and total nitrogen (N) ranged from 0.78 and 0.06% in the 75 to160 cm layer of arable land to 15 and 0.61% in the 0 to10 cm layer of forestland, respectively. Total N was strongly and positively correlated with soil OM (r = 0.99). Exchangeable Al was poorly and negatively correlated with available phosphorous (r = -0.41). Conversion of forestland to arable land reduced the mean available phosphorus (P) from 4.04 ppm to 1.95 ppm most probably due to decline in OM, soil acidification and erosion. Deforestation and subsequent continuous cultivation over the past 25 years apparently amplified the mean exchangeable acids from 0.83 cmol (+) kg-1 to 5.96 cmol (+) kg-1. Soil acidification and related problems were the major challenges of continuous cultivation in the study area. The study indicated that land use change and management practices have had a considerable negative effect on soil physical and chemical properties. Key words: Deforestation, continuous cultivation, land use change, soil properties, soil fertility, soil acidity, Western Ethiopia.

This study assessed farmers’ perception and adaptation options to climate change in six kebeles selected from different agro-ecological zones of Dire Dawa Administration, eastern Ethiopia. Data for the study were collected from 171 respondents selected through multi-stage sampling technique. Descriptive statistics were employed to assess climate change perception differentials among gender, social groups and institutional settings, while multinomial logit model (MNL) was used to identify factors influencing households’ climate change adaptation options. The results revealed an increment in annual (0.2-1.1°C/decade) and seasonal (0.5-1.4°C/decade) temperatures at all stations and the rate of an increment was found to be higher in the highland areas. Similarly, 76.0 and 81.9% of the interviewed farmers were aware of the change in annual and seasonal temperature respectively and their perception appears to be in accordance with the statistical record of these areas. Whereas, both the annual and seasonal precipitations were found to have no trend, except for one station at Dire Dawa where only annual and summer precipitations were found to have an increasing trend and Kulubi where a winter precipitation was found to have a decreasing trend. Farmers’ perception on the patterns of annual and meher precipitations were in line with the observed data at two stations (Kulubi and Dengego). On the other hand, the surveyed farm households in the study area perceived at least one aspect of climate change primarily through their life experience. The majority of farmers (81.87%) adapted to climate change stresses using the adaptation strategies such as soil and water conservation with or without agronomic practices like change in cropping time; crop type and variety and crop diversification. Results of the multinomial logit model showed that farm size, level of education of household head, agro-ecology, livestock owned, farm income and credit service significantly and positively influences one or a combination of climate change adaptation strategies identified by farmers. On the other hand, gender, age of the household head and non-farm income were found to influence the adaptation strategies pursued by farmers negatively and significantly. Therefore, an effort that enhances farmers’ education, farm and livestock productivity, and credit services in accordance with different agro-ecologies so as to create the capacity to adapt to climate induced stresses remain an important strategy that policy makers at all levels of the administration should consider. In addition, sex, age and non-farm income of the household should also be sought critically. Key words: Climate change, adaptation, perception, determinants, multinomial logit model.

This study investigates the soil–plant nutrient status and relationship in Wolaita, Southern Ethiopia. Maize leaves, soil samples and field history were collected. The result indicated that continuous cultivation without fallowing, complete crop residue removal and inadequate fertilization were common practices. The soil was low in organic carbon, total nitrogen, available phosphorus, potassium, sulfur, boron and copper. Tissue analysis indicated 100, 84, 54 and 28% deficiency of nitrogen, phosphorus, potassium and copper, respectively. Significant and positive correlations (r = 0.70, 0.40 and 0.50) of soil phosphorus, calcium and copper with tissue content were observed. Soil pH was correlated with tissue phosphorus (r = 0.4), iron (r =—0.3) and manganese (r = −0.7). Overall, the levels of calcium, magnesium, iron, manganese and zinc were adequate for maize. Therefore, fertilizer application addressing nitrogen, phosphorus, potassium and copper deficiencies is recommended for the study area.

Soil acidity is a critical issue necessitating urgent attention in most highlands of Ethiopia due to its impact on crop production productivity. Application of organic and inorganic amendments could effectively minimize the problem and improve the fertility level of the soil. Accordingly, a greenhouse experiment was conducted to evaluate the effects of sole and combined applications of lime, FYM, compost and P on soil chemical properties incubated at 20, 40 and 60 days. The treatments were arranged in a completely randomized design with three replications. The results indicated that various treatment combinations raised the soil pH at the 40 days of incubation. All treatments showed increased P availability consistently with increasing time of incubation. Maximum available P was observed at the 60 days of incubation due to application of 8 t FYM ha -1 + 30 kg P ha -1 + 5 t lime ha -1 followed by 8 t compost ha -1 + 30 kg P ha -1 + 5 t lime ha -1 . Exchangeable acidity and Al were reduced at the 40 and 60 days of incubation with the application of 30 kg P ha -1 + 10 t lime ha -1 followed by 4 t FYM or compost ha -1 + 15 kg P ha -1 + 10 t lime ha -1 . Highest exchangeable Ca was obtained at 20 days of incubation with the application of 30 kg P ha -1 + 10 t lime ha -1 followed by 4 t ha -1 FYM + 15 kg P ha -1 + 10 t lime ha -1 . Sole addition of 10 t lime ha -1 elevated ECEC from 19.29 to 22.30 cmol c kg -1 at the 40 days of incubation. Likewise, combined applications of 30 kg P ha -1 + 10 t lime ha -1 improved ECEC of the soil from 19.53 to 24.27 cmol c kg -1 at the 40 days of incubation. Integrated applications of organic and inorganic amendments were found more effective to reduce soil acidity and Al 3+ concentration with increasing the fertility of the soil.

Background Soil acidity and low availability of P are among the major problems limiting crop production in the highlands of Ethiopia. The current study was conducted to evaluate the distribution of chemical P forms and selected physical and chemical properties of soils in Cheha and Dinsho districts, southern highlands of Ethiopia. Twelve representative composite soil samples were collected from the surface layer (0–15 cm) and analyzed for selected soil properties. Analysis of available P and oxalate extractable P, Al and Fe, and P fractionation were done following standard procedures. Results The pH of soils in the study area ranged from 4.65 to 5.45. In the study area the Mehlich-3 extractable P ranged from 8.90 to 25.75 mg kg−1, while the Bray-I extractable P varied from 8.54 to 22.81 mg kg−1. The studied soils had a total P content that ranged from medium to very high. Mehlich-3 P was positively and significantly correlated with pH, CEC and OM, while it was negatively and significantly (P ≤ 0.01) correlated with exAc and exAl. Oxyhydroxides of iron and aluminum were dominating the exchange sites of the studied soils. In terms of the relative abundance of P forms, Res-P and HCl-P followed by NaOH-Po and NaOH-Pi were the dominant P forms in Cheha and Dinsho districts respectively. The total sum of readily available P forms (NH4Cl-Pi, NaHCO3-Pi and NaHCO3-Po) did not exceed 4% of the total P. Conclusion Soils of the study area were acidic in reaction and found to have low available P. Given the presence of considerable amount of total P, low P availability and high soil acidity in the study areas, further research has to be done on adsorption characteristics to determine the P requirements of the soils for better P management.

Information on soil fertility status is key in predicting the relative response of soils to fertilizer application and adopting appropriate management practices. The present study was conducted to assess the fertility status of the soils of the Dawja Watershed in Enebse Sar Midir District. 21 composite soil samples were collected from the 0-20 cm soil depth of 7 land units, identified based on their slope and management practices. Except available phosphorus, all the soil parameters were significantly ( P < 0.05) affected by differences in land units. The textural class of the soils varied between sandy clay loam and sandy clay. The bulk density of the soils under the different land units ranged between 1.32 and 1.41 g cm -3 and the total porosity varied from 46.66 to 50.10%. The pH of the soils ranged from 5.7 to 6.8. The organic matter content of the soils was generally low and ranged between 1.17% in cultivated land unit to 2.46% in grazing land unit soils. The total nitrogen content of the soils ranged from 0.13 to 0.19%. Available P (Olsen) was generally high in all the land units and ranged between 17.92 to 23.02 mg kg -1 . The results further showed that the

Information on soil properties and fertility status of soils at farm levels under particular farming system is essential for boosting farm productivity and for sufficient food production. This study was conducted to investigate status and properties of soils under crop-livestock farming system, where crop grains are produced for food security and residues for animal feed and domestic fuel consumption. For the study, two farms under similar farming system were selected from two districts in eastern part of Ethiopia: Adele farm from Haramaya and Bala Langey farm from Kersa districts. Soil samples were collected from crop fields of each farm and analyzed following standard methods for soil physical and chemical analyses. The results indicate that soil textural class is sandy clay loam at both farms. The mean bulk density values were 1.43 and 1.39g cm -3 for Adele and Bala Langey farms, respectively. The soil reaction for Adele farm was neutral (pH=7.23) whereas soils of Bala Langey farm had slightly acidic reaction (pH=6.57). Organic carbon contents of soils of both farms were low, less than 1.5%. Nitrogen was low for Adele farm soils (

Characterization of soils in terms of phosphorus adsorption capacity is fundamental for effective soil phosphorus fertility management and for efficient utilization of phosphorus fertilizers. Thus, this study was conducted to investigate the phosphorus adsorption characteristics of soils of two farms and to elucidate the implication of soil phosphorus adsorption isotherm studies for soil phosphorus fertility management. The two farms, representing the major farming systems of the respective districts, were selected from Adele village in Haramaya district and Bala Langey village in Kersa district in eastern Ethiopia. Soil samples were collected from the crop fields at Adele and Bala Langey farms. Two different P-bearing sources, potassium dihydrogen phosphate (KH2PO4) and diammonium phosphate (DAP-(NH4)2HPO4), were used for the adsorption isotherm studies. The adsorption data were fitted to the linear and Freundlich adsorption isotherm models. Both models revealed that soils of both farms had different P adsorption capacity from the two P sources. Amount of P adsorbed from DAP solution was higher than the amount of P adsorbed Original Research Article Wogi et al.; AJEA, 6(2): 74-82, 2015; Article no.AJEA.2015.066 75 from KH2PO4 solution in soils of both farms. Phosphorus adsorption capacity of Adele farm soils was higher than that of Bala Langey farm soils. Therefore, soils of the two farms should be managed differently for P fertility. Percentages of P adsorbed (% Pa) and P remained in the equilibrium solution (% EC) were also calculated. By plotting the two percentages i.e. % Pa and % EC against the initial concentration of P (IC), two regions were observed. The two regions were described as P intensity and quantity factor windows. Based on the intensity and quantity factor windows, at currently existing soil condition, between 200 and 500 kgha -1 P should be applied as fertilizer to soils of Adele at 0-30 cm depth for immediate benefits and soil P fertility maintenance.

Soil resource information is vital for sound land use planning and sustainable fertility management. This study was carried out with the objective of characterizing and classifying soils of Yikalo Subwatershed at Lay Gayint district, Northwestern Ethiopia. Representative soil pedons were opened along topographic positions and described on genetic horizon basis in the field for their morphological characteristics and analyzed in the laboratory for selected physical and chemical soil properties. The soils were classified following the FAO (2014). The results revealed the presence of variations in the selected morphological properties within a pedon and along the topographic positions. Soils differed in reaction from 4.57 to 6.42. On the surface horizons of the soil pedons, available P content varied from 0.21 to 3.25 mg kg -1 , while exchangeable acidity ranged from 0.17 to 3.65 cmol c kg -1 soil. There was no consistent trend for cation exchange capacity (CEC) and PBS (percent base saturation) with soil depth and topographic positions. The soils in Yikalo Subwatershed were classified as Hyperdystric Cambisols (Humic), Haplic Alisols (Humic), Cambic Umbrisols (Colluvic) , Haplic Luvisols (Epidystric), and Pellic Vertisols ( Mesotrophic). Optimum rates of organic and inorganic amendments should be applied to reduce the level of soil acidity, and improve the fertility level of the soils for better crop production and productivity.

The knowledge of soil properties and availability of reliable soil data play vital role in understanding the soil environment and its services. This study was conducted with the objective of characterizing and classifying soils of Wadla Delanta Massif, North Central Highlands of Ethiopia. Twelve representative soil pedons (profile pits) were opened on various landscape positions, described in the field and horizon-wise samples collected for morphological and physicochemical analysis. Variations in color (moist and dry) within a pedon and among pedons along the toposequence were observed with grayish, dark brownish or black colors dominating the surface layers, while stronger and brighter colors with shades of reddish brown and light brownish gray dominated the surface layers. The soils are heavy clays (35 to 80%), of low bulk density (1.02 to 1.35 g cm-3), acceptable ranges of particle density for mineral soils (2.41-2.82 g cm-3) relatively high total porosity (46.51-60.55%), and high available water holding capacity (129.9-287.9 mm m-1).The soils were slightly acidic to moderately alkaline (6.25 to 8.29) in their reaction, salt free (EC Mn (2.01-9.22 mgkg-1) > Cu (0.80-6.03 mgkg-1) > Zn (0.80-5.80 mgkg-1), all of which were above the critical limit. Based on morphological, physical and chemical analysis, and the FAO-WRB Soil Classification System, the soils are classified as Mazi-Pellic Vertisols, Mazi-Calcic Vertisols, Haplic Cambisols and Mollic Leptosols. The soil potentials are hampered by their stickiness when wet and hard when dry, waterlogging and soil erosion due to inappropriate tilling and timing of cultivation. Therefore, integrated soil management is essential in the area. Key words: Altitude, horizon, pedon, topography.

Additional file 1. Table S1 Mean daily temperature values of different composting methods

For sustainable land management and increased agricultural productivity, detailed and accurate information on land resources, including on land use/land cover dynamics, is required. A study was conducted in Wadla Delanta Massif to investigate land use/cover dynamics over the last four decades (1973-2014) using satellite images (1973 MSS, 1995 TM and 2014 ETM + ). Global positioning system, topographical maps of 1:50,000 scale for ground verification, ArcGIS 10.2 software and ERDAS imagine 10.0 processing and analysis, supplemented with field work were used. Six land use/land cover (LU/LC) types i.e. forest, shrub, grazing, cultivated, bareland and riverbeds were identified. The results showed that there were remarkable spatiotemporal changes in LU/LC. Bareland and riverbeds increased from 17.2 to 32.30% and 1.68 to 2.61% respectively. Forest and shrub lands decreased drastically from 3.98 to 0.47% and 34.86 to 24.26% in 1973 and 2014, respectively. Agricultural and grazing lands also slightly decreased from 33.78 to 32.70% and 8.5 to 7.66% in 1973 and 2014, respectively. From 1973 to 2014, the forest, shrub, grazing and agricultural lands decreased by 90.3, 31.5, 10.08 and 3.36%, whereas the bare lands and riverbeds increased by 89.88 and 57.54%, respectively. The major contributing factors for such variations are population growth and associated needs, land tenure system, incompatible farming system, and lack of alternative energy sources. An integrated approach should be put in place in order to alleviate the current constraints and, improve agricultural productivity and food security in the study area. Keywords : GIS, Image classification, Remote sensing, Supervised classification

A study was conducted in the Tsegede highlands of Tigray Region, northern Ethiopia to determine the changes in some physical and chemical attributes across three adjacent acidic soil sites with different elevation and three land use types. Analytical results of the collected surface layer soil samples showed significant (P ≤ 0.05) correlation of soil bulk density, OM and total N with elevation. In the lower elevation site (Indaslasie), soil OM content declined by about 43 and 52% compared with that of the two higher elevation sites (Cheguarcudo and Indamariam), respectively. Soil pH, exchangeable acidity, exchangeable Al, OM, total N and available phosphorus also exhibited significant (P ≤ 0.05) disparity across the three land use types of the area. Soils of the forest land were less acidic by 0.43 and 0.68 pH units than the cultivated and grazing lands, respectively. The soil OM content of the cultivated land was significantly lower by about 25 and 35% than the grazing and forest land soils, respectively. Available soil P status was low and showed significant correlations with pH (r = 0.65), exchangeable acidity (r = –0.58) and Al (r = –0.53). In general, the study results revealed altitude did not impose any significant effect in aggravating soil acidity whereas land use type affected significantly not only soil acidity but also the important soil fertility related parameters such as OM, total N and available P contents. Therefore, it can be suggested that besides to the usual acid soil management and/or reclamation practices, introducing proper land use management systems are of paramount importance.

Additional file 1. Topography and slope category of sampled agricultural fields in the study area.

Understanding the effects of climate change on land suitability for crop production has become an important issue with respect to food security. The main objective of this study was to evaluate the impacts of climate change on land suitability for rainfed crop diversification under current and future climate change scenario in Legambo sub-watershed. Microcomputer Land Evaluation Information System Decision Support System (MicroLEIS DSS) through the application of Almagra and Terraza models was used. Almagra model assesses the suitability of different soil types to a specific crop. Terraza model provides an experimental prediction for the bioclimatic deficiency. Soil morphological and analytical data were obtained from 4 representative soil profiles and stored in the Soil Database (SDBm). Agro-climatic data for 20 consecutive years (1995-2014), were obtained from National Meteorological Agency and incorporated to the Climate Database (CDBm). A future scenario of climate change was calculated according to the predictions of Intergovernmental Panel on Climate Change (IPCC) on regions of East Africa under scenario Representative Concentration Pathway (RCP) 8.5(high-emission scenario) by 2100. The results show that, the most suitable crops to grow in the study area are sweet potato > sorghum > maize > soybean > wheat in respect of that order. The main limitation factors for land suitability are soil texture and drainage conditions. Bioclimatic deficiency evaluation showed a positive response to climate change, with percent yield reduction decreasing. The net effect of climate change on land suitability is positive for both hypothetical scenarios and therefore, the study area is suitable for rainfed crop production for the selected Land Use Types (LUTs).

A study was conducted on soil management groups of Metahara Sugar estate in order to characterize them in terms of their physical and hydraulic properties, and develop pedotransfer functions for estimating water contents at field capacity (FC) and permanent wilting point (PWP). Soils of Metahara were classified in to six textural soil management groups (soil classes) on the basis of soil moisture content at pF2 and texture to determine irrigation intervals. These are class 1, 2, 3, 4, 5, and 6 with pF2 moisture contents of 75%, respectively. pF2 is the water content at -10 kPa matric potentials. Ninety eight disturbed and undisturbed samples were taken from surface and subsurface layers. The soil analyses result indicated that mean values of the estate soils varied from class to class and with depth in which bulk density varied from 1.01 to 1.43 g/cm3, particle density from 2.23 to 2.76 g/cm3, total porosity from 40.91 to 61.42%, sand content from 10 to 40%, silt content from 13 to 36%, clay content from 33 to 77%, and organic matter content from 1.18 to 2.69%. The available water holding capacity varied from 99.71 to 212.01 mm/m. The mean saturated hydraulic conductivity varied from 0.96 to 5.95 μm/s while the basic infiltration rate varied from 0.43 to 3.68 cm/hr. The soil water retention characteristic curves (SWRCC) indicate the presence of three distinct groups of soils in the Estate instead of six groups. Water retention at any of the matric potential points considered increased from group 1 (classes 1 and 2) to group 3 (classes 5 and 6). Furthermore, the equation developed using clay content and bulk density as predictor variables was found to be the best equation for predicting gravimetric water content at field capacity and permanent wilting point with reasonable accuracy. Based on the results, the existing irrigation scheduling should be revised for the respective three soil groups.

Land suitability assessment plays an important role in identifying biophysical constraints and evaluating potential capacity of land and its sustainable use. Physical land suitability evaluation for irrigation was carried out in the lower Alwero river area of Abobo, western Ethiopia, following FAO methodology for general irrigation farming. The irrigation suitability of five land mapping units (LMUs): 1Ac, 1Bc, 1Ecl, 2Cc and 3Ccl were assessed by considering slope, drainage, top soil texture, sub soil texture, surface stoniness, surface coarse fragments, subsurface coarse fragment, rockiness, depth to solid rock or hardpan, lime, gypsum, electrical conductivity (EC) and exchangeable sodium percentage (ESP). The result revealed that LMU 1Ac, 1Bc and 2Cc, with total area of 22,367.9 ha (83.7%), were moderately suitable (S2). The moderate limiting factors were drainage, top soil texture and subsoil texture. On the other hand, LMU 1Ec1, covering an area of 3,677.6 ha (13.8%) was not suitable (N) for irrigation due to subsurface coarse fragments and depth to solid rock or hardpan. For all LMUs, parameters like lime, gypsum, EC and ESP were not considered as limiting factors.

The study was conducted to investigate the effects of land use, depth and topography on soil physicochemical properties at the Wadla Delanta Massif, northcentral Ethiopia. Four land uses (natural forest, shrub, grazing and cultivated land), three soil depths (0-20, 20-40, 40-60 cm) and three topographic positions (upper, middle and lower) in three replications were considered for this study. A total of 108 composite samples were collected for laboratory analysis. The results show that particle size distribution was affected by the main effects of land use and soil depth; bulk and particle densities, total porosity, organic matter and total nitrogen contents, C:N ratio and available phosphorus were significantly affected by the interaction of land use by soil depth only, whereas, soil pH, electrical conductivity, exchangeable bases, cation exchange capacity, percent base saturation and extractable micronutrients were affected by the interaction effects of the three factors. Highest clay and bulk density were recorded at the bottom layer of the cultivated land soils, while the utmost porosity, organic matter and nitrogen contents, and available phosphorus were recorded at the surface layers of the natural forest land soils. Highest pH was at the bottom layer of the cultivated land at the three topographic positions. Highest exchangeable bases and cation exchange capacity were observed in the bottom layers of soils under the four land use types at the lower topographic position, whilst extractable micronutrients were recorded at the surface layers of the forest land soils at the upper topographic position. In general, most of the measured soil properties were measured better in forest than in other land use soils and the lower topographic positions than the upper and middle ones. Interaction of land use with topography showed negative effects especially on cultivated and grazing land soils in all topographic positions. Therefore, integrated soil fertility management and soil conservation measures are required in all topographic positions to maintain soil physicochemical properties.

A green house experiment was conducted during Oct-Dec2012 to evaluate the efficiency of selected treatment combinations of FYM, gypsum and pore volume (PV) of leaching water on growth parameters (number of leaves, plant height, leaf area, fresh and dry biomass) of maize (Zea mays L.) crop. Treatments included the combinations of the two rates (0 and 20 t ha-1) of FYM, four rates of gypsum (0, 50, 75 and 100% gypsum requirement, GR) and three (1.0, 2.0 and 3.0) PV of leaching water arranged in complete randomized design with three replications. The results indicated that growth parameters of maize showed significant (p < 0.005) response to combined application of treatments. Similarly, the responses of growth parameters to combined application of gypsum and PV of water were also significant. Maximum growth parameters were observed in the plots that received 20 t FYM ha-1 + 100% GR + 3.0 PV of water compared to other combinations. Results also indicated that increasing the GR by 25% showed consistent improvement in crop growth parameters across each PV of leaching water. Analysis of the post harvest soils showed that soils received combined applications of treatments decreased pH, ECe and SAR of saline sodic soils. However, significantly (p < 0.01) higher decrease in pH, ECe and SAR were recorded in the combined application of 20 t FYM ha-1 + 100% GR + 3.0 PV of water. Combination of 20 t FYM ha-1 + 50% GR + 3.0 PV of leaching water reduced pH, ECe and SAR by 7.5, 23.5 and 10.0% over the control, respectively. This combination is deemed suitable for improving soil properties to agriculturally permissible limits and for optimal maize crop production. Hence, this combination can be recommended for the production of economically optimal maize crop production in saline sodic soil of Baile low lands.

Incubation and laboratory experiments were conducted to evaluate the effect of FYM, gypsum and pore volume (PV) of water on ESP and Ksat of saline sodic soils. Factorial combination of three rates of FYM (0, 20 and 30 ton ha-1), four rat of gypsum (0, 50, 75, 100 and 125% GR) and three PV of water (1.0, 2.0, 3.0 and 4.0) were applied into the soil in complete randomized design with three replications. The soils were incubated using a plastic pot for a week followed by leaching with various PV of water. The data obtained subjected to analysis of variance. Results indicated that sole application of gypsum at different rates and their combination with FYM significantly decreased the ESP of the soil compared to FYM and the control. However, larger exchangeable Na released and then decreased the soil ESP with the use of combined FYM and gypsum treatments than sole application of gypsum for every increment in applied PV of leaching water. Similarly, the Ksat of soils was higher in combined than sole application of FYM and gypsum for all applied fixed PV of leaching water. On the other hand, increasing sole application of FYM and gypsum increased the Ksat of soil and the numerical values were significantly (P < 0.05) higher than the control but lower than the different combinations. Though, the Ksat of soil increased with increasing rates of applied FYM and gypsum; these values showed decreasing trend as PV of leaching water increased. In general, the interaction effects of different levels of FYM, gypsum and PV of water were significant (P < 0.05) in improving the ESP and Ksat of the saline sodic soils of Bisidimo. In conclusion, among the various treatments considered, combinations of 20 tons FYM ha-1 with gypsum (50, 75 and 100% GR) rates and leaching up to three PV of water are adequate to reclaim saline sodic soil to permissible limit and then theses combinations are recommended for resource poor farmers. The experiment was laid down in a completely randomized design with two replicates.

Phosphorus (P) adsorption capacity and its relationship with some properties of five different soil types (Fluvisols, Cambisols, Vertisols, Arenosols and Nitosols) of Tigray Region, northern Ethiopia were studied during the main cropping season in 2012. Besides, fractionation of the total soil P in to Ca-P, Fe-P and Al-P was carried out and their relationships with P adsorption characteristics of the soil type under study were also studied. Adsorption data for the different soil types were obtained by equilibrating the respective soil samples for 24 hours at room temperature with 25 ml of 0.01 M CaCl2, containing 0, 60, 120, 180, 240, 300, 360, 420, 480 and 540 mg kg-1 of applied external P as KH2PO4. The results of this study showed that Ca-P was highest followed by Fe-P in all the soils except in the Arenosols. Testing the Langmuir and Freundlich adsorption isotherms both showed well fitted with the correlation coefficients (r) that ranged from 0.951 to 0.999 in all the soils. Comparing the two adsorption models, the Freundlich model was slightly better in Vertisols, Arenosols and Nitosols while the Langmuir model was better in the Fluvisols and Cambisols in predicting P adsorption. The adsorption maximum (b) obtained from the Langmuir isotherm ranged from 296.6 mg P kg-1 soil in Fluvisols to 820.4 mg P kg-1 soil in Vertisols. The constant related to bonding energy calculated from the Langmuir adsorption model varied from 0.0151 to 0.0447 L mg-1. The Freundlich adsorption parameters also ranged from 7.28 to 30.15 mg kg-1 for the Freundlich isotherm constant (Kf) and from 0.4874 to 1.012 for slope of the Freundlich isotherm (1/n). Among the soil properties (CaCO3, CEC, organic matter, EC, pH, and sand, silt, and clay contents), clay content, CEC and CaCO3 were positively correlated with the Langmuir adsorption maximum. The adsorption maximum significantly (P ≤ 0.05) correlated (r = -0.902 but decreased with increasing sand content. The constant (Kf) positively and significantly (P ≤ 0.05) correlated (r = 0.953) with EC of the soil. The remaining soil properties studied were not significantly correlated with the adsorption parameters.

Assessing land use-induced changes in soil properties are essential for addressing issues of agro-ecosystem transformation and sustainable land productivity. In view of this, a study was conducted to assess the impact of land use/land cover on the physicochemical properties of soils of Abobo area, western Ethiopia. Three adjacent land use types, namely forest, grazing and cultivated lands each falling under four land mapping units (1Ac, 1Bc, 2Cc and 3Cl) were considered for the study. A total of 40 random soil samples (0-20 cm depth) were collected to make three composite samples for each land use type across the land mapping units and analyzed for selected soil physical and chemical properties. The results of the study, on one hand, revealed that soil OM, total N, CEC, PBS and available micronutrients (Fe, Mn, Zn and Cu) contents of the cultivated land was significantly (P < 0.001) lower than the adjacent forest land. For instance, soil OM, total N, CEC, PBS, exchangeable Mg and available micronutrients (Mn, Zn and Cu) contents of cultivated land was significantly lower than the adjacent forest land by 32.98, 33.33, 16.16, 17.81, 21.88, 29.47, 40.05 and 53.92%, respectively. On the other hand, the results of the study revealed that exchangeable cations (Mg, K and Na), PBS and available micronutrients (Fe, Mn, Zn and Cu) contents of the gazing land was significantly (P < 0.001) lower than the adjacent forest land. However, significant differences were not observed between the forests and grazing lands in soil OM, total N, CEC and available P. From the present study, it could be concluded that the soil quality and health were maintained relatively under the forest, whereas the influence on most parameters were negative on the soils of the cultivated land, indicating the need for employing integrated soil fertility management in sustainable manner to optimize and maintain the favorable soil physicochemical properties.

A field study was conducted at Dire Dawa, Eastern Ethiopia, with an objective to find out an optimum combination of inorganic (NP) fertilizer and excreta-based vermicompost for best economic yield and quality of tomato and to assess their effect on selected physico-chemical properties of amended soil after crop harvest. The experiment consisted of eight treatments where the mineral (NP) fertilizer and the excreta-based vermicompost were combined in different proportions being arranged in a completely randomized block design replicated three times. Growth, yield and quality attributes of tomato as well as the post-harvest soil nutrient status were markedly influenced by the nutrient treatments. The highest values for the various growth, yield and quality attributing parameters were recorded for the treatment combination consisting 75% of the recommended rate of NP fertilizer + 11.25 ton ha−1 vermicompost (T6), this treatment was also observed to have the highest net benefit with acceptable economic return as well as a fairly high residual soil nutrient status. Following this treatment, is the integration of 50% of recommended rate of NP fertilizer + 7.5 ton ha−1 vermicompost (T3) which surpassed the sole mineral fertilizer and vermicompost in terms of the crop’s yield and its economic return. 25–50% of the recommended rate of chemical fertilizer can be supplemented through vermicompost. However, in order to generate more reliable information, there is a need to conduct more such studies using more integration ratios of these nutrient sources (NP fertilizer and vermicompost) at various soil and agro-climatic conditions.

Composting is one of the integrated waste management strategies used for the recycling of organic wastes into a useful product. Composting methods vary in duration of decomposition and potency of stability, maturity and sanitation. This study was aimed to investigate the comparative effectiveness of four different methods of composting viz. windrow composting (WC), Vermicomposting (VC), pit composting (PC) and combined windrow and vermicomposting (WVC) on the stabilization, maturation and sanitization of mixtures of municipal solid organic waste and dried faecal sludge. The composting treatments were arranged in a completely randomized block design with three replications. The changes in physico-chemical and biological characteristics of the compost were examined at 20 days interval for 100 days using standard laboratory procedures. The analysis of variance was performed using SAS software and the significant differences were determined using Fisher’s LSD test at P ≤ 0.05 level. The evolution of composting temperature, pH, EC, $${\text{NH}}_{ 4}^{ + }$$ , $${\text{NO}}_{ 3}^{ - }$$ , $${\text{NH}}_{ 4}^{ + }$$ : $${\text{NO}}_{ 3}^{ - }$$ ratio, OC, C:N ratio and total volatile solids varied significantly among the composting methods and with composting time. The evolution of total nitrogen and germination index also varied significantly (P ≤ 0.001) with time, but their variation among the composting methods was not significant (P > 0.05). Except for PC, all other methods of composting satisfied all the indices for stability/maturity of compost at the 60th day of sampling; whereas PC achieved the critical limit values for most of the indices at the 80th day. A highly significant differences (P ≤ 0.001) were noted among the composting methods with regard to their effectiveness in eliminating pathogens (faecal coliforms and helminth eggs). The WVC method was most efficient in eliminating the pathogens complying with WHO’s standard. Turned windrow composting and composting involving earthworms hastened the biodegradation process of organic wastes and result in the production of stable compost earlier than the traditional pit method of composting. The WVC method is most efficient in keeping the pathogens below the threshold level. Thus, elimination of pathogens from composts being a critical consideration, this study would recommend this method for composting organic wastes involving human excreta.

Understanding the landscape features of agricultural lands and soil management practices is pertinent to verify the potential and limitations of the soil resources; and devise relevant land management strategies. However, information is lacking in Wolaita, Southern Ethiopia. Thus, this study aimed at investigating the physiographic characteristics of agricultural lands, farmers’ soil fertility management practices and their influences on soil fertility and crop productivity was conducted. The survey involved 789 randomly sampled agricultural lands. Soil sample as well as data on slope, topography, land use, crop rotation, fallowing, cropping intensity, crop residue management, fertilizer use and farmers’ estimated crop yield were collected and evaluated. The result indicated that agriculture has been practiced under diverse slope positions (1–58%). This significantly influenced most of soil physico-chemical properties in which an increase in soil bulk density, and decrease in available phosphorous, exchangeable calcium, extractable boron, copper, iron and zinc with an increase in slope positions were recorded. Furthermore, continuous cultivation without any fallow periods and complete crop residue removal (96%) were common practices. Fertilizer use was not sufficient. The average use (kg ha−1) was 30 and 9 for di-ammonium phosphate (DAP) and urea, respectively, and about 89% of study area received manure below 1.5 t ha−1. All these limitations made farmers to experience lower crop yield than the national average estimates. Based on the result, it is possible to conclude that the following soil management interventions such as soil conservation, application of sufficient organic and inorganic fertilizers are recommended to restore the soil fertility and improve crop productivity.