The mapping of soil nutrients is a key issue for numerous applications and research fields ranging from global changes to environmental degradation, from sustainable soil management to the precision agriculture concept. The characterization, modeling and mapping of soil properties at diverse spatial and temporal scales are key factors required for different environments. This paper is focused on the use and comparison of soil chemical analyses, Visible near infrared and shortwave infrared VNIR-SWIR spectroscopy, partial least-squares regression (PLSR), Ordinary Kriging (OK), and Landsat-8 operational land imager (OLI) images, to inexpensively analyze and predict the content of different soil nutrients (nitrogen (N), phosphorus (P), and potassium (K)), pH, and soil organic matter (SOM) in arid conditions. To achieve this aim, 100 surface samples of soil were gathered to a depth of 25 cm in the Wadi El-Garawla area (the northwest coast of Egypt) using chemical analyses and reflectance spectroscopy in the wavelength range from 350 to 2500 nm. PLSR was used firstly to model the relationship between the averaged values from the ASD spectroradiometer and the available N, P, and K, pH and SOM contents in soils in order to map the predicted value using Ordinary Kriging (OK) and secondly to retrieve N, P, K, pH, and SOM values from OLI images. Thirty soil samples were selected to verify the validity of the results. The randomly selected samples included the spatial diversity and characteristics of the study area. The prediction of available of N, P, K pH and SOM in soils using VNIR-SWIR spectroscopy showed high performance (where R2 was 0.89, 0.72, 0.91, 0.65, and 0.75, respectively) and quite satisfactory results from Landsat-8 OLI images (correlation R2 values 0.71, 0.68, 0.55, 0.62 and 0.7, respectively). The results showed that about 84% of the soils of Wadi El-Garawla are characterized by low-to-moderate fertility, while about 16% of the area is characterized by high soil fertility.

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Heavy metal contamination in the El-Gharbia Governorate (District) of Egypt was identified by using remote sensing, Geographical Information Systems (GIS), and X-ray fluorescence (XRF) spectrometry as the main research tools. Digital Elevation Model (DEM), Landsat 8 and contour map images were used to map the landforms. Different physiographic units in the study area are represented by nine soil profiles. X-ray fluorescence spectrometry (XRF) was used for geochemical analysis of 33 soil samples. Vanadium (V), nickel (Ni), chromium (Cr), copper (Cu) and zinc (Zn) concentrations were measured and they all exceeded the average global concentrations identified by Wedepohl (1995). Ni and Cr concentrations exceeded recommended values in all soil profile horizons (Canadian Soil Quality Guidelines, 2007), while Cu had a variable distribution. Zn concentrations are under recommended concentration limits in most soil samples. Contamination Factor, Pollution Load Index and Degree of Contamination indices were used to assess the environmental risks of heavy metal contamination from the soils. All analysed metals pose some potential hazard and pollution levels were particularly high near industrial and urban areas

Areas contaminated by heavy metals were identified in the El-Gharbia Governorate (District) of Egypt. Identification used remote sensing and Geographical Information Systems (GIS) as the main research tools. Digital Elevation Models (DEM), Landsat 8 and contour maps were used to map physiographic units. Nine soil profiles were sampled in different physiographic units in the study area. Geochemical analysis of the 33 soil samples was conducted using X-ray fluorescence spectrometry (XRF). Vanadium (V), nickel (Ni), chromium (Cr), copper (Cu) and zinc (Zn) concentrations were measured. V, Ni and Cr concentrations exceeded recommended safety values in all horizons of the soil profiles, while Cu had a variable distribution. Zn concentrations slightly exceeded recommended concentration limits. Concentrations were mapped in each physiographic unit using the inverse distance weighted (IDW) function of Arc-GIS 10.1 software. Pollution levels were closely associated with industry and urban areas.

In light of climate change and the ever-increasing population, salt stress has become a critical issue for agriculture and food security. The use of nano-fertilizers in agriculture is a promising application for salt stress management. Therefore, we investigated a hydroponic experiment to evaluate the effect of different nano-fertilizers: macro-nutrient (K2SO4) and micro-nutrient (ZnO and SiO2) on two alfalfa (Medicago sativa L.) genotypes: (Susceptible: Bulldog 505, and tolerant: Mesa-Sirsa) grown with different salt concentrations (6 and10 dS m−1) in split-split design. The results demonstrated that nano-K2SO4 enhanced shoot dry weight, plant height, number of flowers, number of tillers, root length, root fresh weight, and root dry weight under both salt levels. Addition of nano-K2SO4 enhanced plant relative water contents and electrolyte leakage with both genotypes under different salt levels. Nano-SiO2 promoted proline and SOD production with high salinity with values of (0.78 and 1.06 µmol g−1 FW) and 191.15 and 143.46 U. g−1 FW under Bulldog and Mesa-Sirsa, respectively. The application of nano-ZnO promoted plant micro-elements under 6 dS m−1 with both genotypes. The incorporation of nano-fertilizers into hydroponic systems provides a promising strategy, especially in regions with low water quality.