Effects of Acacia Decurrens (Green Wattle) Tree on Selected Soil Physico-Chemical Properties North- Western Ethiopia

Full Length Research

Effects of Acacia decurrens (Green wattle) Tree on selected Soil Physico-chemical properties North- western Ethiopia

Abiot Molla1 and Ewuketu Linger 2

1Department of Natural Resource Management, College of Agriculture and Natural resource, Debre Markos University, Debre Markos, Ethiopia. 2Department of Natural Resource Management, College of Agriculture and Environmental Science, Bahridar University, Bahridar, Ethiopia.

Accepted 24 July, 2017; Published 31 July, 2017.

Many exotic tree species which are introduced in Ethiopia were not screening before their introduced it. This may leads to injure on soil physical, chemical and biological properties. Therefore, the study was initiated to quantify the effects of Accica decurrens trees on major soil properties and nutrients in Fagta Lakoma district, Awi zone North-western Ethiopia. The experiment was laid out in RCBD with two factors: distance from tree trunk (under the tree trunk, edge of the canopy and at 10m of open cultivated lands) and Soil depth (0 – 15cm and 15– 30cm). Two ways analysis of variance (ANOVA) were performed and significant differences were declared at P < 0.05. Soil bulk density was significant at (P<0.05) under the tree trunk with comparing to the open cultivated lands. Soil Moisture content and texture were not significant at p<0.05 along radial distance and soil depth. Soil pH, SOC, OM, TN, P and CEC were significance at p<0.05 along radial distance, but not significance at soil depth except TN and SOC under the tree trunk. The exchangeable K, Na and Mg are not varied significantly at (P<0.05) of the two soil depths and three radial distance, but exchangeable Ca significant under tree trunk and open cultivated lands. The Person correlation also indicated the relationship between moisture content, available phosphors, soil bulk density and radial distance were positive. Radial distances, and SOM, TN and pH are negatively correlated (r2). As conclusion, A. decurrens tree improves soil fertility in small- holder farmers in the study area.

Key words: Open cultivated land, Radial distance, Soil properties

Introduction

Land use changes have remarkable effects on the fertilizers is inadequate (Ogeh and Osiomwan, 2012), dynamics of soil properties (Ozgoz et al., 2013). Changes loss of biological activity and diversity (Yao et al., 2010). land use from forest cover to cultivated land may delay In Ethiopia, rapid population growth and environmental addition of litter, losses nutrient content in soils (Alfred et factors lead to the conversion of natural forest and al., 2008; Ozgoz et al., 2013), increase rates of erosion grassland into cultivated farmland (Gebreyesus, 2013). (Kassa, 2002; Biro et al., 2013), loss of soil organic Such human-induced factors have contributed to soil matter and nutrient (Saha and Kukal, 2015) and degradation and soil loss by deteriorating the soil accelerate rate of soil degradation (Barua and physical and chemical properties and make the Haque,2013). These all process leads to decline in soil ecosystem more delicate and susceptible to land fertility if replenishment with inorganic or organic degradation (Karltun et al., 2013). Study in china has shown that forest destruction accelerated soil salinization (Zhang et al., 2015); Wang et al. (2011) found out that SOM, total N, available P, pH, exchangeable captions *Corresponding author email:[email protected] contents and CEC of the soil decreased signiﬁcantly with 096 Res. J. Agric. Environ. Manage

conversion of forest land to farm lands. Region of Ethiopia. It is bordered on the west by Guanga Many studies in Ethiopia also indicated that decreasing woreda ,on the north by Banja Shekudad, and East Mirab in bulk density and increasing in SOM, total N, Gojjam Zone. The district is located geographically in exchangeable cations and CEC contents, pH, available Figure 1. phosphorous and clay are signiﬁcantly higher in natural forests with comparing farmlands (Eyayu et al. , 2009; Fantaw and Abdu ,2011; Asmamaw and Mohammed , Agriculture and vegetation cover 2013;, Gebreyesus , 2013;Nega and Heluf , 2013). Tree covers is, therefore, play a role in the control of The major land use categories of the district are forest, soil erosion, increasing nutrient inputs through nitrogen agriculture, grazing land, and settlement. Agricultural fixation and increased biological activities by providing lands (60.8%) and forest (19.5%) accounts the largest biomass and suitable microclimate (Ogunkunle and share (FLAO, 2016). There are various sources of Awotoye, 2010). Studies under F. albida in Niger, the soil livelihood for local communities living in the district. away from the base of the trees at 0-15 cm depth had 49 These include Teff (23.3%), potato (23.1%) maize kg N ha-1 and 34 kg P ha-1 while under the tree it (14.9%) and livestock production, timber, charcoal and increased to 155 kg N ha-1 and 44 kg P ha-1 (Kho et al., other non-timber forest products. These products 2001). The same study under F. albida in Ethiopia also obtained from different agricultural practices used to indicated that OC, total N concentration and Available satisfy household consumption and/or generate cash phosphorus were higher under the canopies of the income. scattered F. albida with comparing to open farm lands (Manjur et al., 2014). The same author revealed that soil organic carbon, pH, total nitrogen, and available Topography and climate: phosphorous are signiﬁcantly higher under Croton macrostachyus trees than open farm lands. The area is characterized by flat lands and moderately In recent years, rather than planting and keeping the steep rolling topography which covers 65%. The altitude indigenous tree species, planting of single rows and of the district also ranges between 1800 to 2800 m a.s.l. stands of Acacia decurrens species in the farm lands The district is known to have two agro-climatic zones. have become a dominant feature of the study area in Awi Dega and weyina dega regions were covering 55% and Zones, Ethiopia . This species grows naturally in lower 45%, respectively. The rain fall pattern of the area is mountain valleys. In Ethiopia, it is cultivated above 1,000 bimodal which consisting of the belg rains from the m. It grows well in Moist and Wet Weyna Dega and Dega middle of March to the end of May and the kiremt rains agro climatic zones, 1,600–2,500 m from above sea- that occurs between the months of June to October. level. The trees with strong upright growth, 6–12 m or Mean annual rain fall in the area varies from around more (Bekele, 2007). Although farm land trees are 1500 mm to 2500 mm and the mean annual temperature common in North-western Ethiopia, and the local range from 120c to 220c (FLAO,2016). communities mainly use the species for charcoal production, their effect on soils is not well studied. Therefore, the empirical evidences are required to Method of data collection demonstrate the effects of trees on soil physicochemical properties and to convince land users and policy makers Site selection and characterizations to promote the integration of trees in farming systems. Furthermore, the study may help to understand the The study was carried out on farmers’ farm land having particular choices made by farmers concerning Acacia A. decurrens trees at five year ages to compare the soil decurrens plantations. fertility under and outside the tree canopy. Five isolated The purposes of this study therefore, to investigate the and nearly identical with similar age and compositions of effects of Acacia decurrens on some physicochemical A. decurrens hedgerows near to the farm lands were properties of soil at Fageta lekoma district, Awi zone purposefully selected. The selected area was nearly North-western Ethiopia. similar in terms of slope, length and gradient, elevation, rain fall pattern, and soil type.

Material and Methods Experimental Design, sample size and Data Site descriptions Collection Methods

Locations Two factors were considered as treatments which are distance from the tree base as one factor and depths of Fagta lakoma is one of the districts in the Amhara soil as the second factor. The first factor had three Molla and Linger 097

Figure1. Map of study sites in Fagta lakuma district, Awi zone, Amhara, northeast Ethiopia

levels: under canopy (average distance at 30 cm), at moisture content and Bulk density were studied. Texture the edge of tree canopy (average distance at 45cm) and was determined by hydrometer method (Gee and at open area at 10m from the tree trunk. The second Bauder, 1982) and bulk density by the core method from factor had two levels: at 0-15cm (which represent the oven dry at 105 C0 (Landon, 1991). Soil moisture surface soil) and 15-30cm (which represent subsoil). content was determined gravimetrically through oven This sampling depth was chosen because the roots of A. drying at 105 C0 to a constant weight from known mass decurrens trees are shallow root nature and the roots are and volume of soil sample collected using soil moisture concentrated up to 30cm depth. Generally, the designs cans. will 2*3 factorial arrangements of treatments in randomized complete block design (RCBD) replicated with five stand edges. A total of 30 composited soil Analysis of selected soil chemical properties samples were collected consisting of 5 samples trees. Soil samples were collected by using core sampler Soil pH, Soil Organic Carbon (SOC), Total nitrogen (TN), 2 Available Phosphorous (Av.P), Exchangeable bases size of 25cm . To collect undisturbed soil sample for + 2+ + bulk density, 30×30cm pit were dug out to control soil (Ca , Mg and K ) and Cation Exchange Capacity (CEC) were studied among soil chemical properties. disturbance during sample collection. Soil samples from Total Nitrogen (TN) by Kjeldahl method (Jackson, each treatment and respective levels from each 1958); available phosphorus (P) by Olsen method (Olsen replication were collected using soil auger. Then the soil and Sommers, 1982); exchangeable K by ammonium samples from the same distance and depth were mixed acetate (Jackson, 1958); organic carbon (OC) by Walkley thoroughly to make composite samples for each and Black method (Walkley and Black, 1934), Cation individual tree stands. Finally, 1kg of representative soil Exchange Capacity (CEC) by (Houba et al.,1986), Exa. sample from each composite sample was taken to K, Ca and Mg by ammonium acetate at pH 7.0 using Bahirdar design and monitoring office soil laboratory. flame photometer (Jackson, 1958) were analyzed. The pH of the soil was measured using a digital pH meter in Soil Laboratory Analysis the supernatant suspension of 1:2.5 soils to water ratio(Rhoades 1995). The organic matter content of the Analysis of selected soil physical properties soil was calculated by multiplying the organic carbon percentage by 1.724. Among many of soil physical properties, soil texture, soil 098 Res. J. Agric. Environ. Manage

Statistical Analysis Effect of Acacia decurrens tree on selected soil chemical properties Two ways of analysis of variance (ANOVA) were performed to assess the total variations that occurred within soil parameters and partitioned into radial distance Soil pH values were varied from 5.5 under the tree and effect, and soil depth effect. 4.62 open cultivated lands (Table 2).there were also Mean comparisons were made using the least significance difference at (p=0.0386) under the tree Significant Difference (LSD) test at P< 0.05 significant canopy and open farm lands. However, there is no levels using the general linear model (GLM) procedure of significance difference at (p<0.05) in soil depth under the the statistical analysis system (SAS Institute, 1996). tree and open farm land .Higher pH values were noticed in the closest position than in the midst and the distant positions. This may due to the liter accumulation of under Result and Discussions the tree trunk. In lines to this finding Kahi et al., (2009) reported significant difference (P<0.05) of pH under and There is no any significant interaction effect between outside the canopies of Faidherbia albida and Croton radial distance and soil depth for all parameters. And macrostachyus. Similar to this report, study by Manjur et therefore the discussion is based on radial distance and al., (2014) revealed that there was no significant soil depth effects only. difference (P<0.05) under the canopy of Faidherbia albida and Croton macrostachyus at varying soil depths. Several other studies have also reported significant Effect of Acacia decurrens tree on soil physical difference (P<0.05) of pH under and outside of canopies properties of trees (Getachew et al., 2015; Gindaba et al., 2005; Kamara and Haque, 1992). The soil bulk density (BD) increased from 0.19 to 0.26 as The content of SOC, OM, total N and P depicts a we move from under the canopy of tree to open canopy decreasing pattern from 0-15 to 15-30 cm soil depths (Table 1). Similarly, there was significant difference at (Table 2). In this study, both SOC and OM were (P=0.0002) in BD from the trunk of the tree to the open significant difference (P<0.05) under the canopies of the cultivated land (Table 1). However, there was no Accacia decurence tree and open cultivated lands. The significant difference (P<0.05) in radial distance and soil reason for higher organic carbon under Accacia depth except, open cultivated land. The decline in bulk decurence tree was quite logical as higher contents of density at under the tree might be due to organic matter organic matter on the surface of soil due to the litter fall coverage than at open cultivated land (Kewesaa et al., and decomposition of dead roots from the tree. 2015). In contrary, BD is increasing as soil depth Mekonnen et al., (2009) reported that the content of SOC increase at cultivated field (Table, 1). These may due to and OM showed a decreasing pattern with soil depths frequent cultivation of cultivated field and compaction of and with significance difference from distant positions surface soil which is responsible for the increasing of bulk under Hagenia abyssinica, Senecio gigas, density. Similar to the current study, lower bulk densities Chamaecytisus palmensis and Dombeya torrida trees were observed under isolated Croton macrostachyus canopy. Similarly, Gindaba et al., (2005) and Keswessa (Ashagrie et al., 1999), Milletia ferruginea (Hailu et al., et al., (2015) reported SOC and OM under Croton 2002), Faidherbia albida and Croton macrostachyus macrostachyus and Cordia africana tree, and Hypericum (Manjur et al.,2014) elsewhere in Ethiopia. revolutum tree with were significance. Soil moisture content did not show any significant Total N and C/N ratio were significantly different difference (P < 0.05) between the radial distances (Table (P<0.05) under A. decurence tree species with increasing 1). This result goes well with the finding of Manjur et al., distance from the tree trunk to the open land. But there (2014) who found non-significant difference in moisture were no significance difference in total N and C/N ratio content between radial distances from tree trunk and between the depths of 0-15cm and 15-30cm except Total open cultivated land under F. albida and C. N under the tree trunk (Table 2). There is an increasing macrostachyus in Southern Ethiopia. The result also trend of total N with decreasing radial distance as shown conforms to the studies by Hadgu et al., (2009). in Table 2. This result matches the findings of Hadgu et The textural classification of the study area was al., (2009) who found relatively higher N content and C/N predominantly clay soil. The results showed non ratio under the canopies of the trees than far away from significance both in radial distance and soil depth wise the influence of trees. It also consistence with studies in (Table 1). The study is consistent with studies on different parts of Ethiopia where Keswessa et al., (2015) Hypericum revolutum (Kewesaa et al., 2015), Faidherbia for Hypericum revolutum tree, Getachew et al, 2015 albida, Millettia ferruginea and Cordia africana (Kamara different indigenous trees, Zebene and Agren, (2007) for and Haque, 1992; Hailu et al., 2002), Croton Millettia ferruginea and Cordia africana, Manjur et al., macrostachyus and Faidherbia albida tree (Manjur et al., (2014) for Faidherbia albida and Croton macrostachyus 2014). were reported significantly higher total Nitrogen and C/N Molla and Linger 099

Table 1. Soil bulk density, Moisture content and texture along radial distance and soil depth

Parameters Soil depth (cm) Under tree Edge of tree Open cultivated land (10m from trunk/30cm/ canopy/45cm/ edge of tree) BD(g/cm3 0-15 0.16 ± 0.00a 0.17 ±0.01a 0.22±0.02a

15-30 0.22± 0.02a 0.23 ± 0.03a 0.30±0.01b

Overall 0.19± 0.02A 0.19± 0.02A 0.26±0.03B

MC (%) 0-15 5.19± 0.37a 3.77±0.44a 4.27±0.66a 15-30 4.36 ± 1.11a 3.99±0.59a 4.71± 0.76a Overall 4.78± 0.57A 4.49±0.35A 3.88±0.48A Texture Clay (%) 0-15 51.8±2.3a 50.8±2.9a 52.8±2.2a 15-30 57.0±1.9a 56.8±3.8a 58.0±1.1a Overall 54.4±1.8A 53.8±2.5A 55.4±1.5A Silt (%) 0-15 20.6±0.5a 20.4±0.9a 20.4±1.7a 15-30 19.0±0.7a 19.2±0.4a 18.4±0.7a Overall 19.8±0.5A 19.8±0.5A 19.4±0.9A Sand (%) 0-15 27.6±2.1a 28.8±2.6a 26.8±2.3a 15-30 24.0±1.4a 24.0±3.6a 23.6±1.2a Overall 25.8±1.3A 26.4±2.2A 25.2±1.3A

Mean values followed by different small letters on the same column and capital letters on the same rows are significantly different at (p < 0.05).

ratio under tree trunk compared to the cultivated lands. The effects of A. decurence trees on Exchangeable Available Phosphorus levels in the canopy soil and the Bases (meq/100 g soil) outside canopy soil were significantly different at (P<0.05) (Table 2). But the available phosphorus in the upper The contents of exchangeable K, Na and Mg are not surface (0-15cm) and subsurface soil depths (15-30cm) varied significantly at (P<0.05) at the two soil depths and were not significantly different at (p<0.05). It also showed three radial distance (Table 3). However, there were the a decreasing trend with increasing distance from the tree significant difference of the content of exchangeable Ca base as well as depth wise (Table 2). The finding of under the tree trunk and open cultivated lands (Table 3). Nigusie (2006) under the canopy of Cordia africana, These findings in lines with kassa et al., (2010) reported Faidherbia albida and Croton macrostachyus, Manjur et Exchangeable K, Na and Mg were not significant under al., (2014) Faidherbia albida and Croton macrostachyus, Balanites aegyptiaca trees with comparing to the Keswessa et al., (2015) for Hypericum revolutum, Hailu cultivated lands in Northern Ethiopia. In contrast with this et al., (2002) for Milletia ferruginea tree, Jahantab et.al, finding, Zeben and Agren (2007) reported that the (2013) Myrtus communis were reported higher Available potassium concentrations under Cordia africana were Phosphorus under the canopy of the tree than cultivated significantly higher than cultivated lands. lands. The amount of exchangeable Ca would be higher The level of CEC under the edge of the trees was under tree canopies than the open field (Table 3). Manjur significantly (p<0.05) higher than open farm land (Table et al., (2014) and Kindu et al. (2009) reported that 2). The decreasing trend in the values of CEC was amount of exchangeable Ca was significant variation observed as the distance from the tree trunks increased under the tree canopy comparing with cultivated lands. (Table 2). The higher level of CEC under the tree edge may due to greater amount of litter deposition. The higher amounts of soil organic matter under the tree canopies Correlation between selected soil properties may imply that more cations would be released to the soil through mineralization as a result; the amount of negative Correlations between the selected soil parameter were charges in the soil would be higher (Manjur et al., 2014). indicated in the Table 4. There was a positive correlation Significant CEC values under the tree canopy than the between SOM, total N and CEC. Similarly, positive open farm lands were reported by Manjur et al., (2014) correlation was observed between TN and P as well as under Faidherbia albida and Croton macrostachyus, between CEC and pH. The relationship between SOM Abebe et al., (2001) under C. africana. and BD was negative, which is expected. The higher 100 Res. J. Agric. Environ. Manage

Table 2. Soil pH, CEC, SOC, OM, total N and available P along radial distances and Soil depth

Parameters Soil depth (cm) Under tree Edge of tree Open cultivated land (10m from tree trunk/30cm/ canopy/45cm/ trunk) a a a pH(H2O) 0-15 5.78 ± 0.19 5.13 ± 0.13 4.61±0.170

15-30 5.85 ± 0.19a 5.21 ± 0.11a 4.61±0.093a

Overall 5.82± 0.13A 5.17± 0.08B 4.61± 0.09C

OM (%) 0-15 11.04 ± 0.0.09a 2.91± 0.84a 3.05±0.89a 15-30 10.87 ± 0.04a 2.41 ± 0.83a 2.58±0.54a Overall 4.69±0.15A 2.82±0.26B 2.72±0.23B SOC (%) 0-15 2.89± 0.12a 1.72± 0.22a 1.8± 0.23a 15-30 2.55± 0.08b 1.43 ± 0.21a 1.5± 0.14a Overall 2.72± 0.09A 1.63± 0.15B 1.58± 0.14B CEC (Meq/100 g 0-15 33.60± 3.35a 28.20± 2.72a 29.53±5.07a soil) 15-30 31.22 ± 1.06a 30.20 ± 2.40a 28.04±4.73a Overall 32.41± 1.70A 29.59 ± 1.77AB 28.80 ± 1.48B TN (%) 0-15 0.26± 0.01a 0.18± 0.02a 0.15± 0.02a 15-30 0.23±0.01b 0.16± 0.02a 0.13± 0.01a Overall 0.25± 0.01A 0.17± 0.01B 0.14± 0.01C 0-15 8.50 ±1.67a 8.63 ± 2.23a 6.40± 1.06a Av.P (ppm) 15-30 6.90± 0.55a 5.45 ± 0.48a 5.25±0.84a Overall 7.70±0.87A 7.04±1.19A 5.83±0.66B C/N ratio 0-15 11.04± 0.09a 9.26±0.29a 11.81±0.07a 15-30 10.87± 0.05a 8.81.60±0.39a 11.74±0.14a Overall 10.95±0.06A 9.04±0.24B 11.77±0.07C

Mean values followed by different small letters on the same column and capital letters on the same rows are significantly different at (p < 0.05).

Table 3. Exchangeable Bases (meq/100 g soil) along radial distances and Soil depth

Parameters Soil depth (cm) Under tree trunk Edge of tree canopy Open area(10m from canopy Ex. Mg 0-15 2.74± 0.64a 2.15± 0.57a 2.42±0.58a 15-30 2.55± 0.75a 2.12 ±0.61a 1.92± 0.66a Overall 2.64±0.47A 2.14±0.39A 2.17±0.43A

Ex. Na 0-15 0.70± 0.25a 0.88± 0.21a 0.88±0.22a 15-30 0.71±0.26a 0.89±0.22a 0.88±0.21a Overall 0.70±0.17A 0.90±0.15A 0.88±0.14A Ex. K 0-15 0.42± 0.06a 0.42 ± 0.04a 0.44 ± 0.04a 15-30 0.38± 0.06a 0.43 ± 0.04a 0.41± 0.05a Overall 0.40 ± 0.04A 0.43 ± 0.03A 0.43 ± 0.03A Ex. Ca 0-15 13.81 ± 5.36a 8.40 ± 3.51a 9.23±3.59a 15-30 12.06 ± 4.59a 8.68 ± 3.92a 8.20± 4.35a Overall 12.93±3.34 A 8.54± 2.48CB 8.72± 2.67CB

Mean values followed by different small letters on the same column and capital letters on the same rows are significantly different at (p < 0.05).

SOM, the lower bulk density should be. Radial distances, SOM and TN. Similar studies which showed the inversely and SOM, TN and pH are also negatively correlated, relationships between radial distances and SOM, N and which again is expected. This may the effect of trees on available P, were reported from Ethiopia by Kamara and Molla and Linger 101

Table 4. Person correlation matrix for SOM(%), TN(%), pH, BD(gm/cm3), MC(%), CEC(%) and Av.P (ppm)

Soil properties SOM (%) TN (%) pH(h20) BD(gm/cm3) Mc(%) CEC(%) Av.P(ppm) RD(m) SOM (%) 1 TN(%) 0.786** 1 pH(H2O) 0.773** 0.600** 1 BD(gm/cm3 -0.574** -0.538** -0.278 1 MC(%) -0.056 -0.126 0.295 0.201 1 CEC(%) 0.245 0.310 0.421* -0.009 0.174 1 Av.P(ppm) 0.305 0.303 0.438* -0.219 -0.161 0.069 1 RD(m) -0.942** -0.792** -0.844** 0.548** -0.079 -0.130 -0.282 1

NB. ** Significant at P<0.001, * Significant at P<0.05, RD= Radial distance in meter

Haque, (1992). conditions while carrying out this study. Amhara design and monitoring office Soil Testing laboratory workers were also acknowledged for their cooperation. Conclusion and Recommendations

The study concluded that there were not significant References differences in total exchangeable basis except exc.Ca, soil moisture content and textural classis under the tree Abebe, Y. (1998). Evaluation of the Contribution of canopy and open cultivated lands. However, SOC, OM, Scattered Cordia africana (Lam.) Trees to Soil total N, available P, CEC, pH and Soil bulk density were Properties in Cropland and Rangeland Ecosystems in significantly higher under the base of the tree while western Oromiya, Ethiopia. Skinnskatteberg, Sweden. comparing with outside the canopy area (open cultivated Alfred, E. H., Tom, V.Z. (2008). Land Cover Change and lands). The Person correlation also indicated the Soil Fertility Decline in Tropical Regions. Turk. J. Agric. relationship between moisture content, available 32: 195-213. phosphors, soil Bulk density and radial distance were Ashagrie, Y., Mamo T., Olsson M. (1999). Changes in positive. The Radial distances and SOM, TN and pH are Some Soil Chemical Properties under Scattered Croton negatively correlated. The higher the SOM, the lower the macrostachyus Trees in the Traditional Agroforestry bulk density found under A.decurrens trees indicated System in North-Western Ethiopia, Ethiopian. J. Natural higher the SOM under the tree with comparing to open Resourc., 1(2): 215-233. farm lands. These all finding confirms A.decurrens tree Asmamaw, L., Mohammed A. (2013). Effects of slope improves soil fertility in small-holder farmers of Fagta gradient and changes in land use/cover on selected soil Lakoma district, Awi zone North-western Ethiopia. physic-biochemical properties of the Gerado The researcher encourages the following catchment, Northeastern Ethiopia, Int. J. Environ. recommendation for future research and interventions: Stud., 70: 111–125. a. The A.decurrens trees are found to have positive Barua, S. K., and Haque, S. M. S., (2013). Soil effects on majority of soil physical and chemical characteristics and carbon sequestration potentials of properties. Therefore, there is a need to expand the vegetation in degraded hills of Chittagong, Bangladesh, species in similar agro ecology for those resource poor Land Degrad. Develop., 24: 63-71. farmers in particular and in different farming systems for Bekele, A. (2007). Useful trees and shrubs of Ethiopia : soil nutrients improvement, microclimate amelioration and Identification , Propagation and Management for 17 other uses for the society. Agroclimatic Zones S. D. and P. M. Bo Tengnäs, b. Further study on soil microbial population associated Ensermu Kelbesa, ed., World Agroforestry Centre, East with decurrens trees, allelophatic effects, rooting systems Africa Region, Nairobi Kenya. and their water demand is needed. Biro, K., Pradhan B., Makeschin F.(2013). Land use/land cover change analysis and its impact on soil properties in the northern part of Gadarif region, Sudan, Land ACKNOWLEDGEMENT Degrad. Devlop., 24: 90–102. Eyayu , M., Heluf, G. K., Tekalign M., Mohammed A. The authors thank Debre Markos University for providing (2009). Effects of land use change on selected soil financial support for the research work. Authors also properties in the Tara Gedam catchment and adjacent thank Fageta Lekoma District Agricultural Office for agro-ecosystem, Northwest Ethiopia, Ethiopian. J. Nat. providing the necessary information and facilitating Resources., 11: 35–65. 102 Res. J. Agric. Environ. Manage

Fagta lakoma (2016). Fagta lakoma district Agricultural aegyptiaca , a potential tree for parkland agroforestry and rural development office. systems with sorghum in Northern Ethiopia. J. Soil Sci., Fantaw, Y., Abdu A. (2011). Soil property changes pp.107–114. following conversion of Acacia woodland into grazing Karltun, E., Lemenih, M., Tolera, M. (2013). Comparing and farmlands in the rift valley area of Ethiopia, Land. farmers’ perception of soil fertility change with soil Degrad. Dev., 22: 425-431. properties and crop performance in Beseku, Ethiopia. Gebreyesus, B.T. (2013). Soil quality indicators response Land. Degrad. Develop., 24: 228–235. to land use and soil management systems in Northern Kewessa, G., Lemma, T., Abiot, M. (2015). Effects of Ethiopia’s catchment, Land Degrad. Develop. Hypericum revolutum (Vahl) tree on major soil nutrients Published online, doi:10.1002/ldr.2245. and selected soil Physico-chemical properties in Goba Gee, G.W., Bauder J.W. (1982). Particle Size Analysis in District, Oromia, Ethiopia. Wudpecker. J. Agric. Res., Methods of Soil Analysis. Chemical and Microbiological 4(1): 006 – 013. Properties. Agronomy No.9.2nd Edition. Soil Sci. Soc. Kho, R.M., Yocouba, B., Yaye, M., Ikatam, L. (2001). Am. Medison Wiskonsin, USA. pp. 383-411. Separating the Effect of Trees on Crops: The Case on Getachew, K., Itanna F., Mahari A. (2015). Evaluation of F. albida and Millet in Niger. Int. J. Agroforestry. locally available fertilizer tree/ shrub species in Systems., 52(3): 219-238. Gozamin Woreda, North Central Ethiopia, R. J. Agr. Kindu, M., Gerhard, G., Monika, S., Ottner, F. (2009). Soil Envir. Manage., 4(3): 164-168, Available online at Properties under Selected Homestead Grown http://www.apexjournal.org. Indigenous Tree and Shrub Species in the Highland Gindaba, J., Rozanov, A., Negash,L. ( 2005). Trees on Areas of Central Ethiopia, East Afr. J. Sci., 3(1): 9-17. farms and their contribution to soil fertility parameters in Landon J.R., 1991. Booker Tropical Soil Manual. A Badessa, eastern Ethiopia. Biol. Fertil. Soil., 42: 66-71. handbook for Soil Survey and Agricultural Land Hadgu, K.M, Kooistra, L., Rossing, W.A.H., Ariena, H.C., Evaluation in Tropics and Sub Tropics., Longman Van Bruggen, A.H.C. (2009). Assessing the effect of Scientific and Technical Publishers, New York. Faidherbia albida based land use systems on barley Manjur, B., Abebe, T., Abdulkadir, A. (2014). Effects of yield at field and regional scale in the highlands of scattered F. albida (Del) and C. macrostachyus (Lam) Tigray, Northern Ethiopia. Food. Sec., 1: 337–350. tree species on key soil physicochemical properties Hailu, T, Negash, L, Olsson, M. (2002). Millettia and grain yield of Maize (Zea Mays): a case study at ferruginea from Southern Ethiopia: Impacts on soil umbulo Wacho watershed southern Ethiopia. fertility and growth of maize. Agroforest. Syst., 48: 9- Wudpecker. J. Agric. Res., 3(3): 063 - 073. 24. Mekonnen, K., Glatze, G., Sieghardt, M., Franz, O. Houba, V.J.G., Novozamsky, I., Huybregts, A.W.M., (2009). Soil Properties under Selected Homestead Vader Lee, J.J. (1986). Comparison of soil extractions Grown Indigenous Tree and Shrub Species in the b0.01M CaCl2, by EUF and by some conventional Highland Areas of Central Ethiopia. East. Afr. J. Sci., extraction procedures. Plant. Soil, 96: 433–437 3(1): 9 17. Jackson, M.L. (1958). Soil Chemical Analysis. Prentice; Nega, E., Heluf, G. K. (2013). Effect of land use Halls, Inc.,Englewood cliffs, New Jorsey. Sixth printing. changes and soil depth on soil organic matter, total p. 498. nitrogen and available phosphorus contents of soils in Jahantab,E., Jahanbin, R., Alirezanezhad, A., senbat watershed, western Ethiopia, J. Agric. Biol. Sci., Mohammad, R.M. (2013). The effects of shrubs 8, 206–212, 2013. common myrtle (Myrtus communis) on soil chemical Ogeh, J.S., Osiomwan, G.E. (2012). Evaluation of the and physical characteristics of Basht area, Ann. Biol. Effect of Oil Palm on some Physical and Chemical Res., 4(5): 158-164 Properties of Rhodic paleudults ,Nig. J. Basic. Appl. (http://scholarsresearchlibrary.com/archive.html) Sci., 20(1): 78-82, Available online at Kamara, C.S., Haque, I. (1992). Faidheribida albida http://www.ajol.info/index.php/njbas/index. and its Effect on Ethiopian Highland Vertisosls. Olsen, S.R, Sommers, L.E. (1982). Phosphorus. In: Netherlands. J. Agroforest. Syst., 18: 17-29. Methods of Soil Analysis. Part 2. Chemical and Kahi, C.H., Ngugi, R.K., Mureith, S.M., Ng’ethe, J.C. Microbiological Properties, A.L, Ed. American Society (2009). The canopy effects of Prosopis juliflora (Dc.) of Agronomy, Inc. and Soil Science Society of America, and Acacia tortilis (Hayne) trees on herbaceous plants Inc., Madison, USA. pp. 403-430. species and soil physico-chemical properties in Ogunkunle, C., Awotoye, O. (2010). Soil Fertility Status Njemps flats, Kenya. Tropical and Subtropical under Different Tree Cropping System in a A g r o -ecosyst., 10: 441-449. Southwestern Zone of Nigeria Notulae Scientia Kassa, H. R.W., Blake, C.F., Nicholson, Newton, P. Biologicae Avaliable at: www.notulaebiologicae.ro. (2002). The Crop-livestock Subsystem of Livelihood Ozgoz, E., Gunal, H., Acir, N., Gokmen, F.M., Birol, M., Dynamics in the Harar Highlands of Ethiopia. Budak M. (2013). Soil quality and spatial variability Kassa, H., Gebrehiwet, K., Yamoah, C. (2010). Balanites assessment of land use effects in a typic Haplustoll Molla and Linger 103

Land. Degrad. Develop., 24, 277–286. Walkley, A., Black C. (1934). Examination of the Rhoades, R.E. (1995). The Art of Informal Agricultural Degtjareff method for determining soil organic matter Survey. International Potato Center. Lima. and a proposed modification of the chromic acid Saha, D., Kukal, Z.P. (2015).Soil structural stability and titration method. Soil Sci., 37:29-38. water retention characteristics underdi erent land uses Zeben, A., Agren, G.I. (2007). Farmers’ local knowledge of degraded lower Himalayas of North-West India, Land and topsoil properties of agroforestry practices in Degrad. Develop. 26: 263–271. Sidama, Southern Ethiopia. Agroforest. Syst. 71: 35-48. Nigusie, A. (2006). Status of soil fertility under Zhang, F., Tiyip, T., Feng, Z.D., Kung, H.T., Johnson, indigenous tree canopies on farm lands in Highlands V.C., Ding, J. L., Tashpolat, N., Sawut M., Gui D. W. of Harargie, Ethiopia. MSc. Thesis, Haramaya (2015). Spatio-temporal patterns of land use/cover University, Ethiopia. changes over the past 20 years in the Middle Reaches Wang, Q., Wang, S., Yu X. (2011). Decline of soil fertility of the Tarim River, Xinjiang, China, Land Degrad. during forest conversion of secondary forest to Chinese Develop.,26:284–299. ﬁr plantations in subtropical china, Land Degrad. Develop., 22, 444–452.