Application of geostatistical tools to quantify spatial variability of selected soil chemical properties from a cultivated tropical peat.

摘要

Quantification of spatial variability is a vital prerequisite for precision agriculture. This study aimed to quantify the spatial variability of selected chemical properties in a tropical peat cultivated with pineapples. A 1-ha study plot was established in a commercial pineapple plantation in Simpang Rengam, Johor, Malaysia. Georeferenced topsoil samples (n=60) were obtained systematically from 8x18 m spacings in the x and y direction, respectively. These samples were tested for total C, extractable P, K, Cu, Zn and B. Soil data were first explored using univariate statistics, including normality check, non-spatial outlier detection and data transformation. This was followed by variography and kriging analyses to quantify the spatial variability of the chemical properties. Results revealed a high degree of spatial variability in majority of the chemical properties, which exhibited non-normal distributions with coefficient of variations ranging from 12 to 54%. All properties exhibited a definable spatial structure, which were described by either spherical or exponential models. C, P and B showed strong spatial dependencies. Majority of the properties had short effective ranges. Surface maps of chemical properties clearly showed spatial clustering of test values. Except for K, all other properties showed an acceptable accuracy of interpolated values. These combined data suggest the need for a site-specific approach in managing tropical peat cultivated with pineapples, particularly with regards to nutrient management.