ABSTRACT
The research was elaborated in Kafr El-Dawar area (Egypt northern region)
to study the availability of the soil plant nutrients. The research introduced
three parameters to comprehensively and carefully describe the availability of
the soil plant nutrients: potentiality, gradient and anisotropy. Potentiality defines
the categories of soil ability to supply plant nutrients; meanwhile gradient
expresses the increasing rate of the availability of the soil plant nutrients.
The gradient anisotropy refers to the directions or orientation of the
increasing rate of the availability of the soil plant nutrients. The introduced
parameters enabled to spatially study the availability of the soil plant nutrients.
Analytical data, of soil available phosphorus (P), indicated that P ranged from
0.2 ppm to 11.4 ppm to locate all studied soil samples into the low class of the
soil nutritional P ability. This was not the case of available potassium (K),
where the soil samples were distributed into three available K soil categories:
medium, high, and very high. GIS map of soil P nutritional potentiality for
plant (potato), displayed the soil studied area in one category, as low P soil
nutritional potentiality to coincide with the analytical data classification.
Contrary, the K map classified the soil studied area into three categories of
soil K nutritional potentiality: medium, high and excessive. This obviously
referred that the individual determination of soil K nutritional potentiality is
misleading for interpretation of soil tests because it does care of the spatial
distribution of soil available K. Nearly, all soil samples had high available micronutrients
that they were located in the high category in both classification
of analytical data and GIS maps. GIS gradient maps of the soil available plant
nutrients referred that the soil plant nutrients, exception of K, had two gradients:
non increasing-slight increasing and build up. Gradient of soil available
potassium was classified into four classes: non increasing-slight increasing,
build up, moderately increasing and hike. Regardless potassium case, the
non increasing-slight increasing gradient class dominated the others. GIS maps of anisotropy soil availability of macronutrients (P and K) generally
showed that their gradients mainly increased in two directions: north and
south. The incasing directions of soil availability of micronutrients coincided
with that of the macronutrients.