NULLAssessment and understanding of soil available phosphorus (P) and potassium
(K) content distribution is an important part of deciding whether or not the
fertilization is appropriate or even necessary for a soil. So, the main objective of
this study is to evaluate and map the spatial variability of the available soil P and
K using the geostatistical technique. Georeferencing surface soil samples (0-25
cm) were collected from four sites representing course-textured soils in El-
Kharga and El-Dakhla oases. Ordinary Kriging (OK) technique was applied for
the spatial interpolation of available soil P and K contents. The spatial distribution
of available P and K was analyzed and mapped by Arc GIS (version 10.2.2).
The results showed that concentrations of the available soil P and K ranged from
0.35 to 85.02 mg/kg and from 11 to 6204 mg/kg, respectively. The nugget-to-sill
ratio suggested a strong spatial dependence for both available soil P and K in all
sites of the study area, indicating that the available soil P and K were mainly controlled
by intrinsic factors. The interpolation models varied for both P and K as
well as from site to another site across the study area. Cross-validation proved
that the chosen models were the best fitted semivariogram models to map spatial
distribution of the available soil P and K. The produced maps of spatial distributions
for soil P and K availability were characterized by high accuracy. So, site
specific management can be planned and considered to be applied for this study
area. Also, these maps can facilitate and help in making decisions for choose appropriate
fertilization policies for these soils as well as to avoid adding fertilizers
for sites which do not need to be fertilized. Our results confirmed that the integration
of statistics, geostatistics and GIS provides a powerful tool to assess, describe
and map the spatial variability of the available soil phosphorus and potassium.
As well as to develop high resolution maps that may aid variable rate management
(e.g. fertilization).