Relationship Mechanisms among Soils Fertility Degradation and Physicochemical Properties in Siwa Oasis Soils

Abstract

The recent soil fertility evaluations are evidence of the serious development challenges that many agricultural regions in Egypt; and with growing food demand, soil evaluation will become even more important for the regions in the coming years. The soils studied revealed that the highest ions concentration measured in soil paste extracts were Na+ and Cl- ions. The soil pH could be categorized as slightly to moderately alkaline. Alkaline soils, that have ESP more than 15% and high pH values. In general, most soils were relatively sandy loam. Else, CEC of the soils in the study area was between 3.16 to 24.96 cmolc kg-1. Most soil study high content of CaCO3 and considered as very slightly; slightly; moderately and highly gypsiferous. Data indicated that the available macro and micronutrients in the study area are low. Also, the exchangeable cations were significantly affected by recently environmental changes. This study was undertaken to investigate the spatial variability of selected soil properties using SFI modeling. Up to on the quantitative evaluation of SFI using spatial variability of soil data and modeling techniques is a very important operation. SFI in our study area is very poor fertility (S4= <20) according to classes and values of SFI. Pearson correlation coefficient was calculated to determine the significant positive correlation among SFI and soil pH; EC; CaCO3; OM; total N; available of P, Fe, Mn and Cu; exchangeable of Ca, Na and K. In addition, the SFI is insignificantly and positively correlated with available Zn and exchangeable Mg.