Available potassium evaluation of Gharb El-Mawhoob Soils : El-Dakhla Oasis, Egypt

Abstract EN

Thirty-four soil samples were collected from Garb El-Mawhob soils, northwest of El-Dakhla oasis, New Valley governorate, Egypt to evaluate the soil available phosphorus and its relation with the properties of these soils.

These samples were taken from the surface (0-30 cm) and subsurface layers (30- 60 cm) of 17 soil profiles covered the study area.

Most of the soil samples had a texture of loamy sand, sandy clay loam and clay.

In most cases, the studied soils showed mild alkaline pH (7.4 to 7.8) values.

The electrical conductively (ECe) and Ca-CO3 of these soils varied from low to high levels and ranged from 1.05 to 163 dS/m and from 2.2 to 57.58%, respectively.

The soil organic matter content dif-fered from 0.08 to 2.27%.

Also, the soluble cations and anions in most of the stu-died soils followed the order of Ca+2 >Na+> Mg+2 > K+ and Cl- > SO4= > HCO3-, respectively.

The cation exchange capacity (CEC) and sodium adsorption ratio (SARe) of these soils were ranged from 6.58 to 57.49 cmolc/kg and from 0.11 to 45.18%, respectively.

The NaHCO3-extractable soil phosphorus of these soils varied from 2.25 to 65.35 mg/kg in the surface layer and from 3.34 to 24.49 mg/kg in the subsurface one.

In general, about 50% of the studied soil samples had a low level of availa-ble P (< 6 mg/kg), 24% of them showed a medium level (6 -10 mg/kg) and 26% of them contained a high level of available P (>10 mg/kg).

Moreover, the studied soil samples that had clay and clay loam textures contained a high level of avail-able P than those having other textures.

The available P showed highly signifi-cant positively correlation, with some soil properties, such as OM, HCO3-, CEC and silt contents, while it was negatively correlated with ECe, Na+,CaCO3 and Ca+2