Background, Aim and Scope:
Soil as a landscape body contains wide ranges of physical, chemical, morphological, and mineralogical properties, both laterally and vertically. Soils with similar properties and environments are expected to behave similarly. Statement of land use potential will depend in part on the precision and accuracy of the statements that can be made about the soils. This information has some practical applications in optimizing land management and productivity improvement. The spatial patterns and dependence of some selected physicochemical properties of brackish marsh and surrounding soils were investigated using a 3-D kriging analysis in conjunction with geostatistical model.
Materials and Methods:
Surface and subsurface samples (profile sampling) were obtained across the 40 sampling sites. These samples were stored at 50C until the different physical (particle size) and chemical analyses were initiated. Soil chemical analyses included electrical conductivity (EC), Cl-1, pH, and water soluble Na, S, Ca, Mg, Fe, and Al by inductively coupled plasma spectroscopy (ICP). Soil extraction was performed via an automatic soil extractor. A 1:2 soil to extracting solution ratio was used for all the extractions. The concentration of Cl-1 in the soil sample was determined using a chloride electrode (Model 94-17B). Some selected physicochemical properties were interpolated by kriging. The procedures of univariate/multivariate analyses and kriging techniques were followed to evaluate the spatial dependence of some selected physicochemical properties of soils in the landscape. The kriging procedures included preliminary data analysis, structural data analysis, log kriging estimations, and image generations of spatial results.
Results:
There was a significant spatial dependence and differences for all soil parameters tested. The variability of individual soil property as indicated by coefficients of variation (CV) differed widely. Some soil properties in the lower horizons were more uniform than those at the surface because of less disturbances and effects of micro-topography. Soils may developed markedly contrasting morphologies and properties that may vary laterally (east-west) and vertically (north-south).
Discussion:
Many of the differences and spatial dependence of soil properties in the study area that vary with topography are due to some combinations of microclimate, soil pedogenesis, geological surficial processes, and the sorting effects of water movement.
Conclusions:
Majority of the spatial variability of some soil properties within the study area were caused by the interactive effect of micro-topography and hydrologic pattern. Spatial variability will therefore affect soil performance. A uniform application of any soil amendments like fertilizer or gypsum in the area that possessed spatially variable soil would result in over application in some parts of the area and under application in other areas.
Recommendations and
Perspectives:
Knowledge of the existing soil variability in the area can be utilized to develop a stochastic model that may describe the potential land use capabilities. The prediction is being made by matching the requirements of specific land use to the characteristics of soils in the landscape. Results of an investigation of this type are of great interest to environmental scientist, water resource planners, regulators, decision makers, engineers, soil scientists, and resource managers.
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