research article land use effects on soil quality...

Hindawi Publishing CorporationApplied and Environmental Soil ScienceVolume 2013 Article ID 784989 9 pageshttpdxdoiorg1011552013784989

Research ArticleLand Use Effects on Soil Quality Indicators A Case Study ofAbo-Wonsho Southern Ethiopia

Awdenegest Moges1 Melku Dagnachew2 and Fantaw Yimer3

1 School of Biosystems and Environmental Engineering Hawassa University PO Box 5 Hawassa Ethiopia2Department of Natural Resources Management Wolaita Sodo University PO Box 138 Wolaita Sodo Ethiopia3Wondo Genet College of Forestry and Natural Resources Hawassa University PO Box 128 Shashemene Ethiopia

Correspondence should be addressed to Awdenegest Moges awde mogesyahoocouk

Received 5 March 2013 Revised 29 April 2013 Accepted 10 May 2013

Academic Editor Artemi Cerda

Copyright copy 2013 Awdenegest Moges et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Soil quality assessment is valuable for evaluating agroecosystem sustainability soil degradation and identifying sustainable landmanagement practices This study compared soil quality within culturally protected forest areas and adjacent grassland grazingland and farmland in Abo-Wonsho Southern Ethiopia A total of 40 soil samples (4 land uses times 5 replications times 2 soil depth layers0 to 10 cm and 10 to 20 cm) were collected for analysis Soil textural fractions (ie sand silt and clay percentage) varied with landuse and soil depths even though the textural class across all land use types was sandy loam Bulk density soil organic carbon (SOC)and available potassium (K) varied significantly119875 = 0041119875 = 0001 and119875 lt 0001 respectively with land use and soil depth butother indicators showed no significant difference We conclude soil quality can be protected and maintained by improving existingland use practices within both agricultural and modern forest management areas

1 Introduction

Soil quality can be defined as ldquothe capacity of a specific kind ofsoil to functionwithin natural ormanaged ecosystem bound-aries to sustain plant and animal productivity maintain orenhance water and air quality and support human health andhabitationrdquo [1] It is usually considered to have three mainaspects reflecting physical chemical and biological soil prop-erties and is important for assessment of land degradationand for identification of sustainable land use practices [2 3]The main consequences of inappropriate land use changesare land degradation and soil quality deterioration throughloss of vegetative cover top soilmoisture infiltration capacitywater storage soil organic matter fertility resilience naturalregeneration capacity and a lower water table factors that arecritical for soil health [4] Recent reports on land use and landmanagement effects on soil quality have been documentedparticularly in relation to soil degradation and restoration innorth west Thailand [5] visitors activities and management

on the surface soil [6] and effect of long term cultivation[7] in Turkey and the influence of agricultural managementsystems on soil biological quality in Spain [8] Land use andmanagement are influencing not only soil properties but alsosoil erosion processesWhile unsuitable agricultural practicescan cause soil erosion on the contrary use of cover can reducerisk of erosion [9 10]

There is also a growing interest in understanding and inte-grating local knowledge into natural resource managementstudies [11] Local Indigenous Knowledge (IK) is defined astacit knowledge of a community that is either generatedlocally or imported and transformed before being incorpo-rated into the day-to-day life of a community [12] Infor-mation refined and transferred across successive generationsproduces an understanding of natural resources and relevantecological processes [13]

In Ethiopia IK has been shown to be of paramountimportance for sustainable natural resource management

2 Applied and Environmental Soil Science

activities including soil andwater conservation in Konso [14]irrigation practices in Tigray [15] and stone bund in NorthShoa [16] reporting that forests around churches [17] are themost protected in northern Ethiopia where people considerthe place to be a most holy place

Likewise culturally protected areas such as the Abo-Wonsho are also common in the Sidama Zone of SouthernEthiopia Abo-Wonsho is Sidamarsquos cultural heritage andexemplary natural protection endeavor that has been pro-tected as a sacred place by the Sidama people for the lastseveral decades It is traditionally believed that the areahas been under protection for at least 21 generations (oralcommunication with cultural leaders from Abo-Wonsho)However very little is known about this cultural practice withregard to improving or protecting soil quality its benefitsor its constraints for sustained use of natural resourcesThe extent and rate of soil quality change in relation toculturally protected forest area with the adjacent land usetypes were not identified and quantified Moreover therehas been no documented evidence on how and why suchsystems are maintained for longer time periods Thereforeunderstanding the soilsrsquo physical and chemical qualities andvariability is of paramount importance for utilization andsite-specific management practices of soil resources [18 19]The general objective of this study was to assess soil qualityfor culturally protected forest areas and adjacent agriculturalareas The specific objectives were to quantify and comparechanges in soil physical and chemical quality indicators andto evaluate effects of land use changes on the variability ofselected soil properties

2 Materials and Methods

21 Description of Study Site Abo-Wonsho is located in theoutskirt of Bokasso town which is the capital of Wonshodistrict in Sidama Zone Ethiopia It is about 12 km tothe east of Yirgalem town (Figure 1) and 329 km south ofAddis Ababa Geographically it is located at 06∘4510158401110158401015840N and38∘3010158401610158401015840Ewith an altitude ranging from 1978m (West lowerend) to 2149m (East or upper end) above sea level

211 Climate Geology and Soil The study area has a meanannual rainfall and temperature ranging from 832mm to1658mm and 18ndash21∘C respectively The pattern of rainfalldistribution is bimodal The short rainy season lasts frommid November to February whereas the long rainy season isduring summer and it extends up to October [20] Accordingto [21] the Wonsho district can be divided in to fourlocal climatic zones on the basis of altitudinal and annualrainfall variations as ldquoWet Degardquo ldquoMoist Woyna Degardquo ldquoWetWoyna Degardquo and ldquoWet Kolardquo Accordingly the study siteis observed to be ldquoWet-Woyna Degardquo (Wet mid-highland)Geologically the Precambrian rock with ages of over 600million years forms the foundation of basement complexrocks The Wonsho district also contains a wide variety ofsedimentary volcanic and intrusive igneous rocks whichhave been metamorphosed to varying degrees containing themetallic deposits [21]

212 Farming System and Land Use In the study area agri-culture is characterized by subsistence mixed crop-livestockfarming Most of the area around the homestead is coveredwith perennial Enset (Ensete ventricosum) which is a staplefood and income source Coffee (mainly Coffee arabica) andChat (Catha edulis) and fruit trees such as papaya (Caricapapaya) banana (Musa species) avocado (Persea americana)and mango (Mangifera indica) are also among the widelycultivated crops Vegetables such as potato cabbages onioncarrot pumpkins and green pepper are grown intercroppedeither with Enset or coffee Annual crops such as maizesorghum barley wheat bean pea and haricot bean are mostcommonly cultivated The description of each land use typeis presented as follow

Protected Forest Land It is composed of various indigenoustrees shrubs and bushes like Podocarpus falcatus (Zigba)Strychnos spinosa (Dokma) Croton macrostachyus (Bisana)Arundinaria alpine (Mountain bamboo) Pouteria adolfi-friedericii (or Aningeria adolfi-friedericii Keraro) Juniperusprocera (Tid) Cordia africana (Wanza) Prunus Africana(Tikur-enchet) Euphorbia candelabrum (Kulkual) Millet-tia ferruginea (Birbira) and Vernonia amygdalina (Grawa)In the forest farmers have the right to use the forestfor their livestock grazing However the culture has notallowed replanting (reforestation) and the newly germinatingseedlings have been destroyed by animals browsing andtrampling

Open Grassland It is predominantly of very short grasses andsituated within the protected area This land use system isdenuded of trees shrubs and bushes and open for grazing Itis also believed to be created due to the shrinkage of the forestcover as a result of deforestation due to human and animalinterference

Farmland It is characterized by cultivation of crops Themain cropping system is mixed cropping system wherea combination of trees shrubs and perennial crops suchas coffee Enset and chat are grown together as an agro-forestry system Farmers usually use live fence of various treespecies around and in their farmland for shade firewoodand fodder and soil fertility improvement Some of thetree species that farmers are usually used to grow for soilfertility improvement are Cordia africana (Wanza) Crotonmacrostachyus (Bisana) Millettia ferruginea (Birbira) andVernonia amygdalina (Grawa)

Grazing Land It is used as grazing for cattle and is consideredas communal grazing land It is adjacent to the protectedforest area and owned by a group of farmers in which otherfarmers who do not belong to this group have no right to useThe main difference between the open grassland and grazingland is that open grassland is free for every one to use forgrazing while grazing land is restricted to a certain group offarmers

22 Soil Sampling and Analysis Soil samples were collectedfrom the fourmain land use types described above (protectedforest land open grassland within the culturally protected

Applied and Environmental Soil Science 3

Study area

Awassa Town

Boricha

Loko Abaya

Bensa

Hula

Aroresa

Dale

Chire

Dara

Chuko

Bursa

Malga

Gorche

Arbegona

Wensho

Awasa Zuriya

Shebedino

Aleta Wondo

Wendo Genet

Bona Zuriya

0 25 50125Kilometers

N

Figure 1 Map of the study area

area communal grazing land and farmlands) Soil sampleswere taken from two depths 0 to 10 cm and 10 to 20 cmSample plots had dimensions of 20 times 20m (400m2) withan ldquoXrdquo design and samples taken from the four corners andcenter of each sample plot and pooled Approximately onekilogram of composite sample from each soil depth was takenand put into plastic bags air-dried at room temperaturecrushed homogenized and passed through a 2mm sievebefore laboratory analysis A total of 40 soil samples (fourland use types times five replicates of sample plots times two soildepth classes 0 to 10 and 10 to 20 cm) were collected for soilanalysis Undisturbed samples were takenwith a core samplerthat was 10 cm long and 72 cm in diameter for bulk densitydetermination

Most soil analyses were undertaken at the NationalSoil Laboratory and Research Center Addis Ababa follow-ing standard procedures and methods as described belowBulk density was determined by the core method [22] atWondo Genet College of Forestry and Natural Resourcesrsquosoil laboratory Soil textural fractions were analyzed follow-ing the hydrometric method after removing organic matterusing H

2O2and thereafter dispersing the soils with sodium

hexameta-phosphate [23] The USDA particle size classesnamely sand (20ndash005mm) silt (005ndash0002mm) and clay(lt0002mm) were used to classify the textural classes Soil

organic carbon (SOC) was determined by the Walkley-Black oxidation method [24] Total nitrogen (TN) wasdetermined using the Kjeldahl distillation method [25] andavailable phosphorous (AP) was determined using Olsenrsquosextraction method (UVvisible Spectrometer Lambda EZ201) [26] Available potassium (Av K) was determined bySodium Acetate method [27] the exchangeable bases (Ca2+Mg2+ K+ and Na+) were measured by atomic absorptionspectrophotometry (NOV AA 400) after extraction withammoniumacetate at pH7 [23]The cation exchange capacity(CEC)was determined by extractionwith ammoniumacetate[28] soil pH was determined by potentiometric methodsusing 1 25 soil water ratio Percent base saturation (PBS)was calculated by dividing the sum of the charge equivalentsof the base cations (Ca2+ Mg2+ K+ and Na+) by the CEC ofthe soil and multiplying by 100

23 Statistical Analysis Land use types and soil depth wereused as independent variables (factors) and the soil param-eters as dependent variables The significance difference ofsoil quality indicators with land use types and soil depthwas tested using analysis of variance (ANOVA) following thegeneral linear model (GLM) procedure at (119875 le 005) Tukeyrsquoshonest significance difference (HSD) test was used for mean


Table 1 Soil textural fractions (gKgminus1) and soil bulk density (BD Kgmminus3) in relation to land use (Mean plusmn SE) and soil depths (cm)

Variables Depth (cm) Land use types OverallProtected forest Open grassland Farmland Grazing land

Sand0ndash10 7840 (plusmn136) 7140 (plusmn150) 6040 (plusmn172) 6860 (plusmn98) 6970 (plusmn82)b

10ndash20 7100 (plusmn207) 6900 (plusmn189) 6320 (plusmn160) 6240 (plusmn181) 6640 (plusmn82)a

Overall 7470 (plusmn117)c 7020 (plusmn121)b 6180 (plusmn120)a 6550 (plusmn142)a

Silt0ndash10 1720 (plusmn183) 1720 (plusmn166) 2500 (plusmn126) 2140 (plusmn68) 2020 (plusmn85)a


Overall 1750 (plusmn131)a 1810 (plusmn112)ab 2220 (plusmn160)bc 2290 (plusmn89)c

Clay0ndash10 440 (plusmn75) 1140 (plusmn291) 1460 (plusmn75) 1000 (plusmn89) 1010 (plusmn66)a

10ndash20 1120 (plusmn102) 1200 (plusmn71) 1740 (plusmn98) 1320 (plusmn111) 1345 (plusmn66)b

Overall 780 (plusmn128)a 1170 (plusmn141)b 1600 (plusmn75)c 1160 (plusmn86)b

Bd0ndash10 960 (plusmn30) 1010 (plusmn60) 910 (plusmn40) 970 (plusmn10) 960 (plusmn30)a


Overall 1000 (plusmn20)a 1040 (plusmn60)a 970 (plusmn30)a 990 (plusmn10)a

Overall means within rows and columns followed by different letters are significantly different (119875 lt 005) with land use and soil depths

separation when the analysis of variance showed statisticallysignificant differences (119875 lt 005)

3 Results and Discussions

31 Soil Physical Properties

311 Soil Textural Fractions (gKgminus1) The results of soilphysical properties are presented in Table 1 The soil texturalfractions of sand silt and clay significantly varied with landuse types while sand and clay varied with soil depth and theinteraction effect was significant for sand fraction (Table 2)The overall sand silt and clay fractions were respectivelyhigher in soil under the protected forest followed by the opengrazing lands than in other land use types (Table 2) In thestudied soil clay fraction was less than 200 gkgminus1 across allland use types and soil depths With respect to land usetypes however the mean clay fraction was relatively higher(160 gkgminus1) under farmland and the least in the protectedforest land (78 gkgminus1 Table 1) and was also higher in the 10ndash20 cm soil layers across all land use types

The higher clay fraction in soil under farmland thanother land use types might be due to the fact that cultivationpromotes further weathering processes as it shears andpulverizes the soil and changes the moisture and temperatureregimes [29]Thehigher clay fraction in subsurface layer thanin the top surface soil may indicate possible clay translocationfrom the top layer to the layer below [30 31] The increasein clay fraction with increasing depth and the lowest overallmean proportion of clay fraction compared to the sand andsilt fractions concurs with the results of other studies [18 32]Moreover the textural class across all land use types is sandyloam indicating the homogeneity of soil forming processesand similarity of parent materials [33] However over a verylong period of time pedogenesis processes such as erosiondeposition eluviations and weathering can change the soiltexture [33 34]

312 Bulk Density (Kgmminus3) In the study area the overallmean soil bulk density did not show any significant differencewith respect to land use types (119875 = 0565) and the interactioneffects (119875 = 0091 Table 2) Soil bulk density under differentland use types generally ranges from 970 (in the farmland)to 1040Kgmminus3 (in the open grassland) Similar studies (eg[35]) also reported that land use types and their interactionsdid not affect the soil bulk density However other studies[32 36 37] found that bulk density significantly varied withland use types due to differences in the landmanagement andland use histories

Difference in soil bulk density with soil depth was signif-icant (119875 = 0041 Table 2) higher in the lower (1040Kgmminus3)than in the top surface soil layer (960Kgmminus3) indicating thetendency of bulk density to increase with depth due to theeffects of weight of the overlying soil and the correspondingdecrease in soil organic matter content [34] The relativelylower bulk density in the top surface than in the lower layermay reflect organic matter concentration

32 Soil Chemical Properties

321 Soil Organic Carbon Content (SOC gKgminus1) The overallsoil organic carbon content showed significant variation withland use types (119875 = 0001) soil depths (119875 lt 0001) andtheir interaction effect (119875 lt 0001 Table 4) The overall SOCcontent was higher under protected forest (297 gKgminus1) andgrazing land (260 gKgminus1) than in the farmland (184 gKgminus1Table 3) Across all land uses SOC content was significantlyhigher in the top surface than in the lower layer In the topsurface SOC content was significantly higher under protectedforest land (418 gKgminus1) followed by the grazing land than inother land use types (Table 3) In the lower soil layer SOCcontent did not show any significant differences across allland use types (119875 gt 005 Table 3) The lower SOC contentunder farmland than in grazing land and protected forestcould be due to the reduced amount of organic material


Table 2 Summary of two-way ANOVA for soil textural fractions and bulk density relation to land use and soil depths

Sources of variations Df Sand Silt Clay BdMS 119875 MS 119875 MS 119875 MS 119875

Land use (LU) 3 3147 lt0001 7663 0004 1123 lt0001 0008 0565Depth (119863) 1 1089 0008 0025 0967 11223 0001 0055 0041LUlowast119863 3 5270 0018 3663 0073 1649 0155 0002 0910Error 32 1359 1438 8825 0012

Table 3 SOC (gKgminus1) TN (gKgminus1) CN ratio pH (H2O) Av P (mgKgminus1) and Av K+ (cmol (+)kg soil) in relation to land use and soil depth(cm) (Mean plusmn SE)


SOC0ndash10 418 (plusmn36) 251 (plusmn18) 198 (plusmn17) 302 (plusmn020) 292(plusmn13)b


Overall 297 (plusmn45)a 241 (plusmn20)ab 184 (plusmn13)a 260 (plusmn020)b

TN0ndash10 26 (plusmn08) 14 (plusmn06) 14 (plusmn02) 25 (plusmn004) 17 (plusmn03)a



C N0ndash10 4785 (plusmn1445) 5368 (plusmn3104) 1542 (plusmn343) 1487 (plusmn444) 3296 (plusmn685)a



pH0ndash10 597 (plusmn014) 534 (plusmn031) 615 (plusmn021) 567 (plusmn010) 578 (plusmn011)a


Overall 570 (plusmn016) 537 (plusmn020)a 592 (plusmn016)a 567 (plusmn005)a

Av P0ndash10 1460 (plusmn260) 1130 (plusmn430) 5120 (plusmn1020) 2140 (890) 2460 (plusmn590)a



Av K+0ndash10 028 (plusmn003) 012 (plusmn001) 029 (plusmn004) 013 (plusmn001) 021 (plusmn002)a


Overall 026 (plusmn004)b 011 (plusmn001)a 024 (plusmn003)b 012 (plusmn001)a

Overall means within rows and columns followed by different letters are significantly different (119875 lt 005) with respect to land use and soil depths

being returned to the soil system and high rate of oxidationof soil organic matter as a result of continuous cultivationfor long period of time without fallowing loss of organicmatter by water erosion and removal of green materials[38 39] Other studies (eg [37 38]) also reported that theSOC content of the mineral soil was significantly lower inthe croplands compared to the grazing and native forestland Cultivation promotes SOC loss due to exposure ofmicroaggregate organic carbon to microbial decompositionby changing the moisture and temperature regimes [40] Thehigher overall SOC content in the protected forest than infarmlands may also be attributed to the higher accumulationof organic matter due to high inputs from root biomassand above ground biomass [38 40] The lower content ofSOC under open grassland and grazing land may be due toreduced organicmatter input because of uncontrolled grazingand browsing [39] However according to [41] rating soilorganic carbon content was found to be very low in farmland(184 gKgminus1) and low (260ndash297 gKgminus1) in other land usetypes indicating that soils under the protected forest andadjacent land use types are threatened by the continuous

animal encroachment human interference and intensiveagricultural production systems

322 Total Nitrogen (TN gKgminus1) and Carbon-Nitrogen Ratio(CN) In the study area the TN did not show any significantvariation across all land uses types (119875 = 0322) soil depth(119875 = 0888) and the interaction effect (119875 = 0533Table 4) However the distribution of total nitrogen contentfollowed a similar pattern to organic carbon distributionand was relatively higher in the protected forest followed bythe grazing land than in other land use types Such resultis expected since most soil nitrogen is bound in organiccarbon By contrast [31] reported a significant difference inTN between the forest and cultivated land due to differencesin soil organic matter content intensities of erosion andcultivation Other studies (eg [37]) reported that totalnitrogen was not significantly varied with land uses Thoughnot statistically significant the relatively higher TN in theprotected forest and grazing lands than in the open grasslandand farmland could be associated with the relatively higherorganic carbon which in turn resulted from plant and root


Table 4 Summary of two-way ANOVA for SOC TN CN ratio pH (H2O) Av P and Av K in relation to land use and soil depths

Sources of variations df SOC () TN () CN ratio pH Av P Av K+

MS 119875 MS 119875 MS 119875 MS 119875 MS 119875 MS 119875

Land use 3 222 0001 002 0322 1419 0231 052 0090 16 0093 0061 lt0001Depth (119863) 1 881 lt0001 000 0888 1601 0201 054 0129 311 0505 0024 0066LUlowast119863 3 264 lt0001 001 0533 1146 0318 023 0385 543 0507 0004 0578Error 32 032 002 939 022 685 0007

biomass as well as residues being returned to the soil systemAccording to [41] ratings the TN content in soil of thestudy area was found to be medium under protected forestand grazing land (21 gKgminus1) while being low under opengrassland and farmland (14 gKgminus1) The principal cause forlower contents of total nitrogen comes from biomass removalduring crop harvest and insufficient replenishment throughmanure or fertilizers

Carbon-nitrogen (CN ratio) ratio is an index of nutrientmineralization and immobilization whereby low CN ratioindicates higher rate of mineralization [34] The CN ratio ofthe studied soil did not show any significant variation withland use types (119875 = 0231) soil depth (119875 = 0201) and theirinteraction effect (119875 = 0318 Tables 3 and 4) Similarly [31]reported that CN ratio did not show a significant variationwith land uses The- overall CN ratio was higher in thetop surface soil layer than in the layer below In the studyarea the CN ratio was found to be higher (Table 3) thanthe normal range 10 1 on average [41] expected in mineralsoils However other studies (eg [30]) reported higher CNratios indicating that nitrogen is immobilized at higher CNvalues because of the formation of only slightly biodegradablecomplexes which are low in nitrogen

323 Soil pH (H2O) Soil pH did not show any significant

variation across land use types or soil depths (119875 gt 005Table 4) The low soil pH in the lower soil layer than in thetop surface soil layer (Table 3) might be due to the presenceof relatively higher organic carbon in the top surface soilAccording to [41] rating the overall pH of the studied soilwas found to be moderately acidic

324 Available Phosphorus (Av PmgKgminus1) Theoverall Av Pdid not show any significant difference with land use (119875 =0093) soil depth (119875 = 0505) or their interaction (119875 = 0507Table 4)Themean Av P in the top soil layer was significantlyhigher (5120mgKgminus1) in the farmland compared to otherland use types (119875 lt 005 Table 3) which may be related tothe application of animal manure compost and householdwastes like ashes for soil fertility improvement Moreoverfarmers have been applying Diammonium phosphate (DAP)fertilizer on their farmland The lower Av P content in theprotected forest might be related to phosphorus fixation [18]The overall available phosphorus was lower in the top than inthe lower soil layer (Table 3)

According to [41] rating Av P across all land use was lowexcept in the top soil layer of farmlandTheAv P deficiency insoils of the study areamay be due to the inherent low-P status

of the parent material and erosion loss Other studies [32 3542] also reported that the Av P inmost soils of Ethiopia is lowdue to P- fixation crop harvest and erosion by water

325 Available Potassium (Av K+ cmol (+)kg Soil) Avail-able potassium significantly varied with land use types (119875 lt0001 Table 4) higher in soil under the protected-forest(026) followed by the farmlands (024) than in other land usetypes (Table 3) while no variation was observed with respectto soil depths Although not significant the mean availablepotassium in the top 10 cm was higher under farmland (029)than in the grazing land (013) and open grassland (012) Inthe lower soil depthmeanAv K+ did not show any significantdifference across all land use types but showed a decliningtrend with soil depth

The observed highest concentration of Av K+ underthe farmland and protected forest land was attributed tothe application of household wastes like ash and a relativepumping of potassium from the subsoil by vegetation inthe protected forest land [43] According to [41] rating AvK+ concentration in the farmland and protected forest wasmedium while being low in the open grass and grazinglands The lower Av K+ in the open grass land and grazingland could be probably due to soil degradation and lossesby leaching as the open grassland and grazing land weredenuded of vegetation cover

326 Exchangeable Sodium (Na+) and Potassium (K+ cmol(+)kg Soil) The concentration of exchangeable Na+ was thesmallest component in the exchange complexes Generallythe results indicated that exchangeable K+ significantly variedwith land use types (119875 = 0004) but not with respect tosoil depth (119875 = 0138 Table 6) and the interaction effects(119875 = 0419) higher in the protected forest land and opengrassland (008) than in farmland and grazing land (004)This result was in line with [29] that the concentration of Na+was lower in cropland than in the grazing and native forestSince the concentration of exchangeable Na+ did not exceed1 cmol (+)kg soil [41] the soil in the study area would notbe regarded as sodic soil The pH also showed that the soil isacidic

There was a significant variation in the overall concen-tration of exchangeable K+ with land use types (119875 lt 0001)and soil depth (119875 = 0040) higher under farmland (062)followed by the protected forest land (058) than in thegrazing (032) and open grasslands (030 Table 5) and inthe upper than in the lower soil depths [36] also reportedthat the concentrations of exchangeable K+ was higher in


Table 5 Exchangeable cations (cmol (+)kg soil) cation exchange capacity (cmol (+)kg soil) and percent base saturation () in relation toland use and soil depths (mean plusmn SE)


Ex Na+0ndash10 006 (plusmn0003) 008 (plusmn001) 004 (plusmn001) 003 (plusmn001) 005 (plusmn001)a


Overall 008 (plusmn0016)c 008 (plusmn0005)bc 004 (plusmn0006)ab 004 (plusmn0005)a

Ex K+0ndash10 062 (plusmn002) 032 (plusmn007) 068 (plusmn001) 036 (plusmn007) 049 (plusmn003)b



Ex Ca2+0ndash10 433 (plusmn007) 269 (plusmn060) 417 (plusmn005) 332 (plusmn012) 363 (plusmn020)b


Overall 366 (plusmn034) 254 (plusmn043)a 398 (plusmn010)b 300 (plusmn023)ab

Ex Mg2+0ndash10 075 (plusmn0005) 061 (plusmn007) 073 (plusmn0002) 076 (plusmn004) 071 (plusmn002)a


Overall 073 (plusmn001)b 055 (plusmn006)a 073 (plusmn0003)b 073 (plusmn002)b

CEC0ndash10 1820 (plusmn489) 1044 (plusmn206) 2252 (plusmn224) 1552 (plusmn269) 1667 (plusmn160)a



PBS0ndash10 3995 (plusmn822) 3925 (plusmn942) 2590 (plusmn228) 3432 (plusmn839) 3486 (plusmn435)a



Overall means within rows and columns followed by different letters are significantly different (119875 lt 005) with respect to land use types and soil depths

Table 6 Summary of ANOVA for exchangeable cations CEC and PBS in relation to land use and soil depths

Sources of variations df Ex Na+ Ex K+ Ex Ca2+ Ex Mg2+ CEC PBSMS P MS P MS P MS P MS P MS P

Land use 3 0005 0004 029 lt0001 4205 0005 0084 0001 11954 0093 3483 0964Depth (119863) 1 0002 0138 006 0040 4526 0026 003 0119 0625 0913 1554 0521LUlowast119863 3 0001 0419 0013 0885 0559 0573 0007 0647 4862 0430 5484 0253Error 32 0001 0003 0826 0012 5139 3832

soil under the farmlands compared to the adjacent naturalforest The higher concentration of exchangeable K+ in thetop surface layer than in the lower soil layer (Table 5) suggeststhat vegetation pumps bases such as K+ Ca2+ andMg2+ fromthe subsoil to the topsoil [29] According to [41] ratings thestudied soil under different land use types has medium tohigh concentration of exchangeable K+ (ge06 cmolkg soil)and thus response to K fertilizer is unlikely

327 Exchangeable Calcium (Ca2+) and Magnesium (Mg2+cmol (+)kg Soil) The concentration of exchangeable Ca2+significantly varied with land use types (119875 = 0005) andsoil depth (119875 = 0026) higher in the farmland (398) andprotected forest land (366) than in other land use types(Table 5) The low exchangeable Ca2+ in the grazing land andopen grassland was probably due to the removal of vegetationcover as a result of human and livestock interference Inthe top surface soil layer the concentration of exchangeableCa2+ was higher in the protected forest (433) and farmlands(417) than in open grassland (269 Table 5)The significantly

higher concentration of exchangeable Ca2+ in the top thanin the lower soil layer was probably due to the applicationof household wastes (ash) in the fields because ash is a goodsource of Ca2+ K+ P and Mg2+ [44] and pumping of basesfrom the subsoil by the vegetation and returning them intothe topsoil [29] A critical concentration of 02 cmolkg soilis required for tropical soils [41] and this would indicatethat exchangeable Ca2+ is not a limiting in the soil ofstudy area Concentration of exchangeable Mg2+ showed asignificant variation with land use types (119875 = 0001 Table 6)while no variation was observed with respect to soil depth(119875 = 0119) Exchangeable Mg2+ was lower under opengrassland than other land use types (Table 5) Generally theconcentration of exchangeable Mg2+ was higher (sufficient)than the critical level of 05 cmolkg soil as suggested by[41] a concentration less than this value would require anapplication of magnesium limestone accordingly

328 Cation Exchange Capacity (CEC cmol (+)kg Soil) andPercent Base Saturation (PBS ) CEC did not show any


significant variation across all land use types (119875 = 0093Table 5) soil depth (119875 = 0913) or the interaction effects(119875 = 0430 Table 6) Though not statistically significantCECwas relatively higher in the farmland (2068) followed byprotected forest (1810) than in other land use types (Table 5)According to [41] ratings the concentration of CEC wasfound to be low both in the open grassland and grazing landindicating the low level fertility status of the soil under thetwo land use types [33] The soil fertility level both underfarmland (2068) and protected forest (1810) was mediumdue to the application of animal manure house hold wastesand residues which are sources of Ca2+ K+ P Mg2+ [44]and due to the relatively higher content of organic matterrespectively

Percent base saturation (PBS) is frequently used as anindication of the fertility status of soil [30] The PBS did notsignificantly vary with land use types (119875 = 0964) soil depth(119875 = 0521) and the interaction effects (119875 = 0253 Table 6)However the PBS was relatively higher under grazing land(3443) than other land use types and in the top than in thelower soil layer (Table 5)

4 Conclusions

Variations in soil quality indicators with respect to land useand soil depths were investigated in the Abo-Wonsho areaSoil textural fractions variedwith land use while silt clay andbulk density differed with soil depths Among soil chemicalquality indicators SOC available K+and exchangeable basesvaried significantly with land use Human mismanagementland resources excessive livestock grazing in the protectedforest areas and intensive agricultural production in adjacentfarmland have caused deterioration in soil quality indicatorsThis documents that the cultural forest management systemhas not protected soil quality

ThoughAbo-Wonsho was believed to be protected for thelast 21 generations there has been no improvement in the soilquality when compared to the adjacent land use Thereforein order to improve soil quality reverse deterioration andmaintain long-term productivity of the agricultural land thefollowing practices are suggested (1) integrating existingculturalmanagement practices with appropriate technologiessuch as reforestation excluding the forest from human andlivestock interference and controlling soil erosion in the area(2) strengthening and expanding existing fertility manage-ment practices such as organic fertilizer (household wastesmanure composts) to sustain agricultural production (3)providing technical support to the concerned cultural leadersis crucial Finally Abo-Wonsho and its surrounding areas arelacking scientific studies on forest resources like species com-position structure diversity and management Identifyingand characterizing soil types and distribution are also amongthe critical research gaps that need to be filled for this area

Acknowledgments

The authors greatly acknowledge the cooperation and sup-port of the farmers in the Abo-Wonso area They are grateful

for the financial support for the research by the Chris-tensen fund through Center for Environment and Societyat HU-CA The anonymous reviewersrsquo comments are greatlyacknowledged

References

[1] D L Karlen M J Mausbach J W Doran R G Cline R FHarris and G E Schuman ldquoSoil quality a concept definitionand framework for evaluationrdquo Soil Science Society of AmericaJournal vol 61 no 1 pp 4ndash10 1997

[2] A RDexter ldquoSoil physical qualitymdashpart ITheory effects of soiltexture density and organicmatter and effects on root growthrdquoGeoderma vol 120 no 3-4 pp 201ndash214 2004

[3] M J Singh Dr and K L Khera ldquoPhysical indicators of soilquality in relation to soil erodibility under different land usesrdquoArid Land Research andManagement vol 23 no 2 pp 152ndash1672009

[4] F Khormali M Ajami S Ayoubi C Srinivasarao and S PWani ldquoRole of deforestation and hillslope position on soilquality attributes of loess-derived soils in Golestan provinceIranrdquoAgriculture Ecosystems and Environment vol 134 no 3-4pp 178ndash189 2009

[5] P Vityakon ldquoDegradation and restoration of sandy soils underdifferent agricultural land uses in northeastThailand a reviewrdquoLand Degradation and Development vol 18 no 5 pp 567ndash5772007

[6] T Yuksek O Kurdoglu and F Yuksek ldquoThe effects of land usechanges and management types on surface soil properties inKafkasor protected area in Artvin Turkeyrdquo Land Degradationand Development vol 21 no 6 pp 582ndash590 2010

[7] E Ozgoz H Gunal N Acir F Gokmen M Birol andM Budak ldquoSoil quality and spatial variability assessment ofland use effects in a typic haplustollrdquo Land Degradation andDevelopment 2011

[8] F Garcıa-Orenes A Roldan J Mataix-Solera et al ldquoSoilstructural stability and erosion rates influenced by agriculturalmanagement practices in a semi-arid Mediterranean agro-ecosystemrdquo Soil Use andManagement vol 28 no 4 pp 571ndash5792012

[9] F Garcıa-Orenes C Guerrero A Roldan et al ldquoSoil microbialbiomass and activity under different agricultural managementsystems in a semiarid Mediterranean agroecosystemrdquo Soil andTillage Research vol 109 no 2 pp 110ndash115 2010

[10] F Garcıa-Orenes A Cerda J Mataix-Solera et al ldquoEffects ofagricultural management on surface soil properties and soil-water losses in eastern Spainrdquo Soil and Tillage Research vol 106no 1 pp 117ndash123 2009

[11] E Barrios andM T Trejo ldquoImplications of local soil knowledgefor integrated soil management in Latin Americardquo Geodermavol 111 no 3-4 pp 217ndash231 2003

[12] World Bank Indigenous Knowledge Local Pathways to GlobalDevelopment Knowledge and Learning Center Africa RegionWorld Bank 2004

[13] R R Pawluk J A Sandor and J A Tabor ldquoThe role of indige-nous soil knowledge in agricultural developmentrdquo Journal ofSoil amp Water Conservation vol 47 no 4 pp 298ndash302 1992

[14] B Tesfaye Understanding Farmers Explaining Soil and WaterConservation in Konso Wolaita and Wollo [PhD thesis]Wageningen University Wageningen The Netherlands 2003


[15] H Solomon and K Yoshinobu ldquoTraditional Irrigationmanage-ment in Betmera-Hiwane Ethiopia the main peculiarities forpersistence of irrigation practicesrdquo Journal of Mountain Sciencevol 2 pp 139ndash146 2006

[16] M Alemayehu F Yohannes and P Dubale ldquoEffect of indige-nous stone bunding (KAB) on crop yield at Mesobit-GedebaNorth Shoa Ethiopiardquo Land Degradation and Development vol17 no 1 pp 45ndash54 2006

[17] W Alemayehu Ethiopian church forests opportunities andchallenges for restoration [PhD thesis] Wageningen UniversityWageningen The Netherlands 2007

[18] F Yimer S Ledin and A Abdelkadir ldquoSoil property variationsin relation to topographic aspect and vegetation communityin the south-eastern highlands of Ethiopiardquo Forest Ecology andManagement vol 232 no 1ndash3 pp 90ndash99 2006

[19] F Bastida A Zsolnay T Hernandez and C Garcıa ldquoPastpresent and future of soil quality indices a biological perspec-tiverdquo Geoderma vol 147 no 3-4 pp 159ndash171 2008

[20] Ethiopian National Meteorology Agency (ENMA)Meteorolog-ical Data Addis Ababa Ethiopia 2008

[21] Sidama Zone Finance and Economic Development sector(SZFEDS) ldquoSocio-economic studyrdquo Southern Nations National-ities People Regional state Ethiopia 2007

[22] J R Blake and K H Hartge ldquoBulk Densityrdquo inMethods in SoilAnalysismdashPart 1 Physical and Mineralogical Methods A KluteEd pp 363ndash376 American Society of Agronomy MadisonWis USA 2nd edition 1986

[23] C A Black D D Evans J L White L E Ensminger andF E Clark Methods of Soil AnalysismdashPart 1 Physical andMineralogical Properties Including Statistics ofMeasurement andSampling American Society of Agronomy MadisonWis USA1965

[24] M Schnitzer ldquoTotal carbon organic matter and carbonrdquo inMethods of Soil AnalysismdashPart 2 Agronomy Monograph A LPage R H Miller and D R Keeney Eds vol 9 pp 539ndash577 American Society of Agronomy Madison Wis USA 2ndedition 1982

[25] J M Bremner and C S Mulvaney ldquoNitrogen-Totalrdquo inMethodsof Soil Analysis A L Page R H Miller and D R Keeney Edsvol 2 pp 595ndash624 American Society of Agronomy MadisonWis USA 1982

[26] S R Olsen and L A Dean ldquoPhosphorousrdquo in Methods ofSoil AnalysismdashPart 2 Chemical and Microbiological PropertiesC A Black Ed vol 9 pp 1035ndash1049 American Society ofAgronomy Madison Wis USA 1965

[27] B J J Jones Laboratory Guide For Conducting Soil Tests andPlant Analysis CRC press LLC 2001

[28] H D Chapman ldquoCation exchange capacityrdquo inMethods of SoilAnalysis C A Black Ed pp 891ndash901 American Society ofAgronomy Madison Wis USA 1965

[29] F Yimer S Ledin and A Abdelkadir ldquoConcentrations ofexchangeable bases and cation exchange capacity in soils ofcropland grazing and forest in the Bale Mountains EthiopiardquoForest Ecology and Management vol 256 no 6 pp 1298ndash13022008

[30] W Chesworth Encyclopedia of Soil Science Springer Dor-drecht The Netherlands 2008

[31] S Khresat J Al-Bakri and R Al-Tahnan ldquoImpacts of landusecover change on soil properties in theMediterranean regionof northwestern Jordanrdquo Land Degradation and Developmentvol 19 no 4 pp 397ndash407 2008

[32] M Sintayehu Land Use Dynamics and its Impact on SelectedPhysicochemical Properties of Soils in Yabello Woreda of BoranaLowlands Southern Ethiopia [MS thesis] Haromaya Univer-sity Haromaya Ethiopia 2006

[33] H D Foth Fundamentals of Soil Science John Wiley and SonsNew York NY USA 8th edition 1990

[34] N C Brady and R R Weil The Nature and Properties of SoilsPrentice-Hall Upper Saddle River NJ USA 13th edition 2002

[35] T Gebeyaw Soil Fertility Status as Influenced by Different LandUses inMaybarAreas of SouthWello Zone Ethiopia [MS thesis]Haromaya University Haromaya Ethiopia 2006

[36] M Lemenih E Karltun and M Olsson ldquoAssessing soil chemi-cal and physical property responses to deforestation and subse-quent cultivation in smallholders farming system in EthiopiardquoAgriculture Ecosystems and Environment vol 105 no 1-2 pp373ndash386 2005

[37] A Moges and N M Holden ldquoSoil fertility in relation to slopeposition and agricultural land use a case study of umbulocatchment in Southern Ethiopiardquo Environmental Managementvol 42 no 5 pp 753ndash763 2008

[38] F Yimer S Ledin and A Abdelkadir ldquoChanges in soil organiccarbon and total nitrogen contents in three adjacent landuse types in the Bale Mountains south-eastern highlands ofEthiopiardquo Forest Ecology and Management vol 242 no 2-3 pp337ndash342 2007

[39] G Girmay B R Singh H Mitiku T Borresen and R LalldquoCarbon stocks in Ethiopian soils in relation to land use andsoil managementrdquo Land Degradation and Development vol 19no 4 pp 351ndash367 2008

[40] D C Reicosky and F Forcella ldquoCover crop and soil qualityinteractions in agroecosystemsrdquo Journal of Soil and WaterConservation vol 53 no 3 pp 224ndash229 1998

[41] J R Landon Ed Booker Tropical Soil Manual A Handbook forSoil Survey and Agricultural Land Evaluation in the Tropics andSubtropics Longman Scientific and Technical New York NYUSA 1991

[42] N Wakene and G Heluf ldquoForms of phosphorus and status ofavailable micronutrients under different land-use systems ofalfisols in Bako Area of Ethiopiardquo Ethiopian Journal of NaturalResources vol 5 pp 17ndash37 2003

[43] H L Bohn B L Mcneal H L Orsquoconnor B L Mcneal and GA Orsquoconnor Soil Chemistry JohnWiley amp Sons New York NyUSA 3rd edition 2001

[44] J C Voundi Nkana A Demeyer and M G Verloo ldquoChemicaleffects of wood ash on plant growth in tropical acid soilsrdquoBioresource Technology vol 63 no 3 pp 251ndash260 1998

Submit your manuscripts athttpwwwhindawicom

Forestry ResearchInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Environmental and Public Health

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Applied ampEnvironmentalSoil Science

Volume 2014

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Atmospheric SciencesInternational Journal of



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International Journal of

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Geological ResearchJournal of

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BiodiversityInternational Journal of


ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OceanographyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


ClimatologyJournal of


activities including soil andwater conservation in Konso [14]irrigation practices in Tigray [15] and stone bund in NorthShoa [16] reporting that forests around churches [17] are themost protected in northern Ethiopia where people considerthe place to be a most holy place

Likewise culturally protected areas such as the Abo-Wonsho are also common in the Sidama Zone of SouthernEthiopia Abo-Wonsho is Sidamarsquos cultural heritage andexemplary natural protection endeavor that has been pro-tected as a sacred place by the Sidama people for the lastseveral decades It is traditionally believed that the areahas been under protection for at least 21 generations (oralcommunication with cultural leaders from Abo-Wonsho)However very little is known about this cultural practice withregard to improving or protecting soil quality its benefitsor its constraints for sustained use of natural resourcesThe extent and rate of soil quality change in relation toculturally protected forest area with the adjacent land usetypes were not identified and quantified Moreover therehas been no documented evidence on how and why suchsystems are maintained for longer time periods Thereforeunderstanding the soilsrsquo physical and chemical qualities andvariability is of paramount importance for utilization andsite-specific management practices of soil resources [18 19]The general objective of this study was to assess soil qualityfor culturally protected forest areas and adjacent agriculturalareas The specific objectives were to quantify and comparechanges in soil physical and chemical quality indicators andto evaluate effects of land use changes on the variability ofselected soil properties

2 Materials and Methods

21 Description of Study Site Abo-Wonsho is located in theoutskirt of Bokasso town which is the capital of Wonshodistrict in Sidama Zone Ethiopia It is about 12 km tothe east of Yirgalem town (Figure 1) and 329 km south ofAddis Ababa Geographically it is located at 06∘4510158401110158401015840N and38∘3010158401610158401015840Ewith an altitude ranging from 1978m (West lowerend) to 2149m (East or upper end) above sea level

211 Climate Geology and Soil The study area has a meanannual rainfall and temperature ranging from 832mm to1658mm and 18ndash21∘C respectively The pattern of rainfalldistribution is bimodal The short rainy season lasts frommid November to February whereas the long rainy season isduring summer and it extends up to October [20] Accordingto [21] the Wonsho district can be divided in to fourlocal climatic zones on the basis of altitudinal and annualrainfall variations as ldquoWet Degardquo ldquoMoist Woyna Degardquo ldquoWetWoyna Degardquo and ldquoWet Kolardquo Accordingly the study siteis observed to be ldquoWet-Woyna Degardquo (Wet mid-highland)Geologically the Precambrian rock with ages of over 600million years forms the foundation of basement complexrocks The Wonsho district also contains a wide variety ofsedimentary volcanic and intrusive igneous rocks whichhave been metamorphosed to varying degrees containing themetallic deposits [21]

212 Farming System and Land Use In the study area agri-culture is characterized by subsistence mixed crop-livestockfarming Most of the area around the homestead is coveredwith perennial Enset (Ensete ventricosum) which is a staplefood and income source Coffee (mainly Coffee arabica) andChat (Catha edulis) and fruit trees such as papaya (Caricapapaya) banana (Musa species) avocado (Persea americana)and mango (Mangifera indica) are also among the widelycultivated crops Vegetables such as potato cabbages onioncarrot pumpkins and green pepper are grown intercroppedeither with Enset or coffee Annual crops such as maizesorghum barley wheat bean pea and haricot bean are mostcommonly cultivated The description of each land use typeis presented as follow

Protected Forest Land It is composed of various indigenoustrees shrubs and bushes like Podocarpus falcatus (Zigba)Strychnos spinosa (Dokma) Croton macrostachyus (Bisana)Arundinaria alpine (Mountain bamboo) Pouteria adolfi-friedericii (or Aningeria adolfi-friedericii Keraro) Juniperusprocera (Tid) Cordia africana (Wanza) Prunus Africana(Tikur-enchet) Euphorbia candelabrum (Kulkual) Millet-tia ferruginea (Birbira) and Vernonia amygdalina (Grawa)In the forest farmers have the right to use the forestfor their livestock grazing However the culture has notallowed replanting (reforestation) and the newly germinatingseedlings have been destroyed by animals browsing andtrampling

Open Grassland It is predominantly of very short grasses andsituated within the protected area This land use system isdenuded of trees shrubs and bushes and open for grazing Itis also believed to be created due to the shrinkage of the forestcover as a result of deforestation due to human and animalinterference

Farmland It is characterized by cultivation of crops Themain cropping system is mixed cropping system wherea combination of trees shrubs and perennial crops suchas coffee Enset and chat are grown together as an agro-forestry system Farmers usually use live fence of various treespecies around and in their farmland for shade firewoodand fodder and soil fertility improvement Some of thetree species that farmers are usually used to grow for soilfertility improvement are Cordia africana (Wanza) Crotonmacrostachyus (Bisana) Millettia ferruginea (Birbira) andVernonia amygdalina (Grawa)

Grazing Land It is used as grazing for cattle and is consideredas communal grazing land It is adjacent to the protectedforest area and owned by a group of farmers in which otherfarmers who do not belong to this group have no right to useThe main difference between the open grassland and grazingland is that open grassland is free for every one to use forgrazing while grazing land is restricted to a certain group offarmers

22 Soil Sampling and Analysis Soil samples were collectedfrom the fourmain land use types described above (protectedforest land open grassland within the culturally protected


Study area

Awassa Town

Boricha

Loko Abaya

Bensa

Hula

Aroresa

Dale

Chire

Dara

Chuko

Bursa

Malga

Gorche

Arbegona

Wensho

Awasa Zuriya

Shebedino

Aleta Wondo

Wendo Genet

Bona Zuriya


N
































































MS 119875 MS 119875 MS 119875 MS 119875 MS 119875 MS 119875













































4 Conclusions



Acknowledgments



References


















































Journal of












Volume 2014

Advances in









Geophysics















Study area

Awassa Town

Boricha

Loko Abaya

Bensa

Hula

Aroresa

Dale

Chire

Dara

Chuko

Bursa

Malga

Gorche

Arbegona

Wensho

Awasa Zuriya

Shebedino

Aleta Wondo

Wendo Genet

Bona Zuriya


N
































































MS 119875 MS 119875 MS 119875 MS 119875 MS 119875 MS 119875













































4 Conclusions



Acknowledgments



References


















































Journal of












Volume 2014

Advances in









Geophysics






































































MS 119875 MS 119875 MS 119875 MS 119875 MS 119875 MS 119875













































4 Conclusions



Acknowledgments



References


















































Journal of












Volume 2014

Advances in









Geophysics














































4 Conclusions



Acknowledgments



References


















































Journal of












Volume 2014

Advances in









Geophysics

















































Journal of












Volume 2014

Advances in









Geophysics














research article land use effects on soil quality...

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