CHARACTERIZING SPATIAL VARIABILITY OF SOIL PARAMETERS USING GEOSTATISTICS AND GEOGRAPHIC INFORMATION SYSTEM

Geostatistics and GIS techniques are a useful tool to characterize soil spatial variability in a large area with appropriate statistical precision for planning proper agricultural strategies and thus the problem of limited agricultural land of our country could be solved. Interestingly, different soil parameters behaved differently, as indicated by statistical measurements including coefficient of variance, spatial dependency, and sampling range. Such analyses can save time and expenses, while being statistically of great precision and usability. An accurate site-specific fertilization scheme for precision farming could more easily be developed from the interpolated map which could help our farmer in future.

Spherical semivariograms were developed and a strong to moderate spatial dependence was observed for all selected parameters which imply that their spatial dependence might be controlled by both intrinsic variations of soil properties and extrinsic factors such as human induced activities. Distribution maps, derived by kriging interpolation, illustrated that these studied area were characterized by moderate to high value of cation exchange capacity (CEC) and available sulfur in south. Available potassium, available phosphorus and neutral pH varied all over the studied area, where as total nitrogen and electrical conductivity had high concentration at the northwest corner. The areas with low soil organic carbon concentrations (0.12-1.46%) were mainly located in northeast of Jessore Sadar. %Sand, %silt and %clay had distribution trends which were different from each other. Notably available sulfur showed a different trend in spatial distribution from south to north. These results are reflection of many factors including soil pH, CEC, OC, amount of moisture held by soil particles, fertilizer application, animal manure application with different amendments, intensive cropping system, different land use pattern, topography of the field at different weather condition and texture percentage.

Geostatistics provides a set of statistical tools for incorporating the spatial coordinates of soil observations in data processing, allowing for description and modeling of spatial patterns, prediction at unsampled locations, and assessment of the uncertainty attached to these predictions (Burgess et al., 1981). Until geostatistics were introduced in the middle of last century, quantifying and modeling of the spatial distribution pattern of a given.

The main objective of the research are as follows:

1. Characterizing and mapping of spatial variability of soil parameters.

2. To develop a digital prototype model of geostatistical database for further use

Scope

The spatial variability is also an indication of the variable precision and hence its applicability. The kriged maps for different soil parameters indicates the variability and distribution of soil parameters in the area which is of great use for planning appropriate strategies for cultivation of different plants. The usability of such a distribution map can also increase if the farmers in the area become familiar with the characteristics related to the analyzed soil properties and accordingly can plan appropriate agricultural strategies, including fertilization. Bangladesh faces hundreds of problems in management of natural resources as well as manmade resources. So the applications of GIS/RS tools have become inevitable.

• Supervision