ASSESSMENT OF SOIL DEGRADATION IN ZARIA AREA, KADUNA STATE, NIGERIA.
ASSESSMENT OF SOIL DEGRADATION IN ZARIA AREA, KADUNA STATE, NIGERIA.
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Date
2014-08
Authors
AMINU, Zuni
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Abstract
This study aimed at an assessment of soil degradation in the Zaria area. Land degradation was assessed through a time- series analysis of Landsat Thematic Mapper 1990, Enhanced Thematic Mapper+, 1999 and NigeriaSat-1 2009 satellite imageries of the study area. The imageries were classified into seven different land use/cover types using the Maximum Likelihood Classifier. The second part of the research entailed field assessment of the physico–chemical status of the surface soils of the area with a view to demonstrating its degradation. Twenty five composite soil samples comprising of four sub-samples were taken from five different land uses (plantation, badland, fadama, cultivated and scrubland land uses) and analysed for key soil physico-chemical properties, including particle size distribution, bulk density, porosity, moisture content, organic matter content, exchangeable cations, CEC and pH. The third part of this research involved a farm-level survey of farmers perception of soil degradation problem and coping strategies through the use of structured questionnaires and focus group discussions. The analysis of variance (F-ratio) was used to test for variations in the selected soil properties over the five different land uses while the students t-test was used to test for significant association between pairs of land uses. Chi square analysis was used to test for significant changes in landuse/ land cover over the period under study, significant associations between farmers‘ socio-demographic characteristics and coping strategies adopted. In addition, a Likert scale test was used to analyse respondents‘ attitudes to soil degradation and perceptions of the severity of soil degradation. The result of LULC showed that land use changes/ exchanges are occurring at rates not lower than 1.6% per annum. The results also show an upward trend for built up area. Result of Chi-square analysis carried out to determine the level of significant changes in the areal coverage of the different land use and land cover types for the periods studied showed statistical significance at p< 0.01, with a calculated X2 value of 612.09 and a table value of 26.2.
The results of soil physic-chemical analysis show soils in the study area are generally sandy, have high bulk density and medium to low mean porosity values. The mean moisture content range between 14.88-25.02% , with the highest value in Fadama land use and plantation (17.6%) and the lowest moisture contents are found within the degraded land (16.8%) and cultivated land (14.9%). The low CEC values over cultivated and badlands show that soils under these land uses have been degraded. However, the range of the pH values over the different land uses show that the soils are slightly acidic. The differences in the soil organic matter content amongst the different landuses, by analysis of variance are statistically significant at the 0.01 level. The value is lowest over the badland (0.25g/kg-1) and highest over the plantation (1.77g/kg-1). The result of soil quality ratings shows that soils in the study area have been degraded. Similarly, results of soil management survey show respondents between the ages of 20 to 60 are actively engaged in farming and family sizes are large. Major soil management practices are mixed cropping and crop rotation. Results show statistically significant association between respondents‘ level of education, income, landownership and actual coping strategies adopted. Farmers‘ most commonly observed soil degradation indicators are erosion-based and include rills, stoniness , loose soils, sheetwash, infestation by parasitic angiosperms, root exposure and red soil. The findings show that both the scientific and farmers views agree that soil degradation is pervasive in the study area but unlike the scientific assessment of degradation, the most commonly recognised soil degradation indicators for farmers are plant/production related.
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ASSESSMENT OF SOIL DEGRADATION, ASSESSMENT OF SOIL DEGRADATION