A Generalized Additive Soil Depth Model for a Mountainous Semi-Arid Watershed Based Upon Topographic and Land Cover Attributes

Uganda Government embarked on promoting sedentary agriculture in Karamoja agro-pastoral semi-arid livelihood zone, which experience rapid environmental and high soil quality (SQ) decline. However, studies on sedentary agriculture’s impact on soil quality using farmer’s knowledge is limited. Consequently, a survey was carried out in Karamoja (Iriiri, Matany Sub-counties of Napak of districts and Rengen sub-county of Kotido) to determine the soil quality indicator parameters based on the farmers knowledge in order to build a local soil knowledge data base to better inform sustainable land use strategies. Using a semi-structured questionnaire, forty indigenous farmers per sub-county, were interviewed between August and September, 2015. The study took into account the social demographic characteristics of the people, farming enterprises, methods of crops production, crops yields trends, causes of the perceived yields trends and soil quality indicators. Prospects of developing Karamoja indigenous knowledge data base lies in visible feature that predict soil quality. Farmers used 36 parameters to determine SQ. The parameters were clustered into five categories; soil, crop, biological, environmental and management each category contributing to 42, 19,14,8 and 17% of the total indicators, respectively. The relationship between age group and the perceived indicators of soil fertility was statistically significant (p-value = 0.045) with the majority stating that they use either soil colour, soil depth or soil texture to express the fertility of soil. The farmer’s soil quality indicators assessed in this study, is important in establishing indigenous-scientific hybrid knowledge data base to enhance soil fertility maintenance and better inform policy makers and other stakeholders on development of sustainable land use strategies.

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Land degradation trend assessment over Iberia during 1982-2012

Cuadernos de Investigación Geográfica ◽

10.18172/cig.2945 ◽

2016 ◽

Vol 42 (1) ◽

pp. 89 ◽

Cited By ~ 13

Author(s):

C.M. Gouveia ◽

P. Páscoa ◽

A. Russo ◽

R.M. Trigo

Keyword(s):

Land Cover ◽

Land Degradation ◽

Ipcc Report ◽

Change Context ◽

Hydrological Stress ◽

Trend Assessment ◽

Semi Arid Region ◽

One Year ◽

Land Improvement ◽

Semi Arid

Land degradation is recognized as an important environmental and social problem in arid and semi-arid regions, particularly within a climate change context. In the last three decades the entire Mediterranean basin has been affected by more frequent droughts, covering large sectors and often lasting more than one year. The Iberian Peninsula has been equally affected by intense drought events since the 1980s. According to the latest IPCC report the Mediterranean region will suffer further hydrological stress in the coming decades, as a consequence of diminishing of precipitation and increasing of average and extreme temperatures. This climatic outlook coupled with the land abandonment and/or intensification of some areas requires a continuous monitoring and early detection of degradation. The present work intends to contribute to such objectives.Land degradation could be stated as a longstanding deterioration in ecosystems productivity. Here we assess the ability of NDVI to be used as an indicator of land degradation over Iberia, from 1982 to 2012. The negative trends of the residuals obtained after removing the precipitation influence on NDVI were assumed to indicate land degradation. A widespread land improvement was observed over Iberia with few hot spots of land degradation located mainly in central and southern sectors and in east Mediterranean and Atlantic coasts. The comparison of spatial patterns of residual trends with dryness for the aridity regions over Iberia highlighted the relatively small fraction of land degradation that experiences an increased dryness, although almost totality belonging to semi-arid region. On the other hand, land improvement is only associated with a tendency of wetness in the northeastern humid sector. Moreover, less than 20% of the area presenting land degradation corresponds to regions associated with land cover changes, being the new land cover types associated with transitional woodland-shrub, permanent and annual crops and permanently irrigated land areas.

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