Theses and Dissertations

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Browsing Theses and Dissertations by Author "Ahukaemere, Chioma Mildred."

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    Sequestration and dynamic of carbon and nitrogen in soils of dissimilar lithologies under different land use types in Southeastern Nigeria
    (Federal University of Technology, Owerri, 2015-06) Ahukaemere, Chioma Mildred.
    The study was conducted to determine carbon and nitrogen sequestration and dynamics in soils developed on different parent materials (Coastal Plain Sand, Falsebedded Sandstones and Shale) under different land use types (forest, fallow and cultivated lands) in South-eastern Nigeria. Geology maps were used to guide the location of sampling sites. Three parent materials and three different land use types in each of the parent materials were randomly selected. The study was a three factor experiment laid in a randomized complete block design (RCBD). A total of 27 profile pits were studied. Soil samples were collected from each of the profiles according to their horizons. Undisturbed soil samples for determination of bulk density were collected in core samplers. Small portions of the samples were air dried, crushed and sieved using a 2-mm sieve in preparation for laboratory analyses. Carbon and Nitrogen forms and sequestration, morphological and physico-chemical properties of soils were determined. Data were subjected to ANOVA , multiple regression, coefficient of variation and correlation analyses. From the results, carbon sequestration ranged from 3229 gCm2in Falsebedded sandstone-derived soils to 3648 gCm2 in Shale-derived soils, and did not differ significantly across the soils. Nitrogen sequestration differed significantly (p < 0.001) with soils derived from Coastal plain sands having higher quantity (248.00 gNm-2) while the least was recorded in soils formed from Shale (91 gNm2). The C sequestration capacity of the soils of the different land use types varied significantly (p < 0.05) with fallow soils derived from Falsebedded Sandstone and Coastal plain sand containing the highest quantities (4753 gCm-2 , 4222 gCm-2). Carbon and nitrogen sequestration increased with horizon thickness in all the profiles across the soils studied. The mean total carbon contents ranged from 39.20 to 82.80 gkg-1across the soils and did not follow uniform pattern of distribution down the profiles, except in fallow soils of the Falsebedded Sandstone where it increased with depth. Soils derived from Shale had the least quantity of total carbon while those of Falsebedded Sandstone had the highest value. Forest soils had higher quantity of total carbon (109.20, 42.40 gkg-1) compared to those of fallow and cultivated soils of the Falsebedded sandstone and Shale . Organic carbon constituted about 58% of total carbon in Shale-derived soils, 20.81% in Coastal plain sand and 27.66 % in Falsebedded sandstone –derived soils. In soils of the different land use types, forest soils contained significantly higher proportion of organic carbon, followed by fallow and lastly by those of the cultivated lands. Organic carbon correlated significantly with clay (r = 0.513, 0.578) (p < 0.001), WSA (r = 0.506, 0.626, 0.646) (p < 0.001) and BD (r = - 0.537, - 0.900, -0.736 ) (p < 0.001) respectively. The mean total nitrogen contents of the soils varied from 5.49 - 8.24 mg/kg in soils of dissimilar parent materials, 3.60 - 14.33 mgkg-1, 7.33 – 8.87 mgkg-1, 2.01 – 10.49 mg/kg in soils of the different land use types. Soils formed from Coastal plain sand and Falsebedded sandstone contained significantly higher (p < 0.01) quantity of total nitrogen than those of Shale. In soils of the different land use types, forest soils contained significantly higher (p < 0.001) proportion of total nitrogen (14.33, 10.49 mgkg-1) than fallow and cultivated soils. Soils formed from Falsebedded sandstone and Shale had significantly higher (p < 0.001) proportions of available N compared to those of Coastal plain sand. In soils of the different land use types, forest soils had significantly higher proportion of available N compared to fallow and cultivated soils. Soils developed on different parent materials under different land use types had varying colour matrix ranges. Soil texture ranged from sand, loamy sand to sandy loam in soils derived from Coastal plain sand and Falsebedded Sandstone, loam, sandy clay loam, silt clay loam to clay in Shale￾xiiderived soils with soils formed from Shale containing significantly (p < 0.001) higher proportion of clay (263 gkg-1) than those of Falsebedded sandstone (77 gkg-1) and Coastal plain sand (90 gkg-1). The mean bulk density (BD) values ranged from 1.06 to 1.22 gcm-3in soils derived from the three parent materials. Forest soils had the least bulk density values (0.98, 1.09, 1.08 gcm-3) compared to other land uses. In soils of different parent materials, Shale derived soils had highest percentage moisture content (12.49%) while those derived from Falsebedded sandstone had the least amount (9.09%). In soils under the three land use types, forest and fallow soils had significantly higher (p < 0.001) quantity of soil moisture than the cultivated soils. Shale-derived soils had significantly higher (p < 0.001) stable aggregates (29.23%, 1.35 mm) than those derived from Coastal plain sand and Falsebedded sandstone. In soils of the varying land uses, soils of the forest had significantly higher (p < 0.001) stable aggregates compared to those of fallow and cultivated lands. Soils were slightly acidic across the parent materials and land use types. Significantly (p < 0.01) least proportion of Calcium (Ca) (2.76 cmolkg-1) was recorded in soils of the Falsebedded sandstones while those developed on Shale had the highest quantity (4.28 cmolkg-1). Significantly higher percentage base saturation was obtained in soils derived from Shale (91.4%) while the least value was obtained in Falsebedded sandstone-derived soils (68.71%). Taxonomic classification was done to the Subgroup level. The soil classes derived from soil taxonomic classification of the USDA was correlated with the World Reference Base. Soils were classified as Grossarenic Kandiudults (USDA), Chromic Acrisols (WRB), Typic Kandiudults (USDA), Rhodic Acrisols (WRB), Lithic Kanhapludults (USDA), Rhodic Acrisols (WRB), Arenic Kandiudults (USDA), Chromic Acrisols (WRB), Vertic Paleudults (USDA), Haplic Acrisols (WRB), Entic Paleudults (USDA), Haplic Acrisols (WRB), Psammentic Hapludults (USDA), Arenic Acrisols (WRB)