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Geostatistical approach to the mapping of acid sulfate soils
|Title:||Geostatistical approach to the mapping of acid sulfate soils|
|Authors:||Ahmad, Faridah Hj|
|Abstract:||Acid sulfate soils are common along the west coast of West Malaysia. These soils occur in small isolated areas and are difficult to locate. One approach is by analyses of spatial dependence of some soil properties typical of acid sulfate soils determined on samples in those areas. Geostatistics permits analysis of spatial dependence and interpolation of soil properties at unsampled locations. These methods were used to analyze soil properties in the Kuala Selangor area/ West Malaysia which are usually characteristic of acid sulfate soils. Spatial dependence was observed in soil pH/ extractable Al/ soluble SO4 and electrical conductivity.|
The surface 0-15 cm of oxidized soil/ had approximately equal ranges of spatial dependence of soil pH/ extractable aluminum/ soluble SO^ and electrical conductivity. At the 15-30 cm depth/ extractable Al had a greater range of spatial dependence than did soil pH. Extractable Al is an important characteristic of acid sulfate soils especially when considering soil acidity and liming. Range of spatial dependence of extractable Al is useful in determining the sampling distance. These data suggest that there should be no more than 4 km between samples and preferably much less. The map of individual soil properties was useful in indicating location and extent of acid sulfate areas. The coincidence of isarithms of soil pH/ extractable aluminum/ soluble SO4 and electrical conductivity at 0-15 cm and 15-30 cm depths indicates acid sulfate areas.
Sampling frequency was probably inadequate to reveal spatial dependence in nutrient concentrations of oil palm in the Kuala Selangor area. Detrimental effects of acid sulfate soils were evident in lower P concentrations in oil palm fronds.
In the wetland rice area/ pH of dry soil was used as an indication of possible acid sulfate soils. Using this criterion/ areas of potential acid sulfate soils were greater than those indicated by the soil survey map although there were large estimation variances. Low density sampling in some areas may account for some of the reasons.
Thus spatial dependence analyses by the geostatistical approach is useful in providing base information for the soil survey and also in mapping specific soil constraints. Locations and extent of soil constraints were napped with a known precision.
|Appears in Collections:||
Ph.D. - Agronomy and Soil Science|
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