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University of Nairobi (2011)

Impact of land use and cover change on soil quality and pasture productivity in semi-arid rangelands

Emmanuel, Zziw A.

Titre : Impact of land use and cover change on soil quality and pasture productivity in semi-arid rangelands

Auteur : Emmanuel, Zziw A.

Université de soutenance : University of Nairobi

Grade : Doctor of Philosophy (PhD) 2011

Résumé partiel
The impact of land use and cover change on soil quality and pasture production was investigated in the rangelands of Nakasongola District, Uganda, Landsat (TM) images of 1986 and 1990 and Landsat (ETM+) of 2000 and 2004 for Nakasongola District were used to determine the extent and patterns of land use and cover change using the Integrated Land and Water Information Systems (ILWIS) 3.6 software. A modified-Whittaker sampling design was used to collect soil and pasture samples in three land cover types (bare, herbaceous and woody) under three production systems (settled, semi-settled and non-settled). The soil samples were analyzed for selected chemical and physical properties while pasture samples were oven dried for biomass yield. Analysis of variance, discriminant analysis and principle component analysis were conducted using XL-Stat software to differentiate the sites and ascertain the effects of different land cover and use types on soil properties. Multivariate analysis for 18 properties of soil was conducted for physical (5), chemical "(7), organic matter (3) and aggregate stability (3) for the upper 15 ern of soil which were combined into a single general indicator of soil quality (GISQ). The area covered by grassland decreased by 13.1% from 90,020 ha in 1986 to 78,199 ha in 2004. Between 1986 and 1990, much of the grasslands were converted into bush land (38,608 ha), woodland (19,659 ha) and cropland (9,159 ha) while between 1990 and 2000, 21,838, 5,912 and 4,506 ha of grassland were converted to woodland, cropland and bush land respectively and between 2000 and 2004, 33,354, ha were converted to woodland, 12,029 ha to bush land and 6,114 to crop land. In general, bush and woody encroachment engulfed approximately 65%,50% and 54% of grasslands In the periods of 1986 - 1990, 1990 - 2000 and 2000 - 2004, respectively. Soils from bare land under non-settled production systems had significantly high levels of clay (p

Mots clés : Soil quality ; Pasture productivity ; Semi-arid rangelands ; Land use

Présentation

Page publiée le 21 novembre 2013, mise à jour le 29 décembre 2017