Assessment and spatial variability mapping of soil available phosphorus and potassium of coarse-textured soils in new valley, ُُEgypt using geostatistical technique

الملخص EN

Assessment 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).