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Soil salinity is considered the most serious socio-economic and environmental problem in arid and semi-arid regions. This study was done to estimate the soil salinity and monitor the changes in an irrigated palm grove (42 ha) that produces dates of a high quality. Topsoil samples (45 points), were taken during two different periods (May and November), the electrical conductivity (EC) and Sodium Adsorption Ratio (SAR) were determined to assess the salinity of the soil. The results of the soil analysis were interpolated using two geostatistical methods: inverse distance weighting (IDW) and ordinary Kriging (OK). The efficiency and best model of these two methods was evaluated by calculating the mean error (ME) and root mean square error (RMSE), showing that the ME of both interpolation methods was satisfactory for EC (−0.003, 0.145) and for SAR (−0.03, −0.18), but the RMSE value was lower using the IDW with both data and periods. This can explain the accuracy of the IDW interpolation method. This model showed a dominance of soil salinity distribution in the South and South-East of the study area during the first season, and for the second season, the salts were concentrated in the middle of the area. Several factors could interact in this variation such as the topographic direction of the water flow and the aridity of the climate (evaporation). From this study emerges the need to maintain a better management of agricultural water and soils, avoiding salt accumulation, to ensure a good yield and the sustainability of agriculture in arid environments.

The concept of erodibility has gained a great importance in the field of soil erosion modelling and applications of soil conservation. Soil erodibility factor has become one of the key factors which determine soil particles resistance to be detached by water erosion. This study was performed to determine soil erodibility factor and assess spatial variability of soil erodibility using geostatistics at El Hammam catchment. In this study 51 samples of surface soil (0-20cm) were collected across the study area of 1000 Ha by preparing point map at GIS. Sampling points were identified in field by a Global Positioning system. Some soil properties and organic matter were measured at laboratory, and permeability and structure were determined using soil texture analysis. Amount of soil erodibility changed from 0.16 to 0.66. The variability analysis has shown that soil properties and erodibility factor have varied significantly in cropland and have ranged from 63% in organic matter and 39% in K factor. The statistical analysis indicated negative correlations of erodibility with clay, organic matter and permeability and negative correlations of this factor with silt, sand and soil structure. Based on kriging interpolation method, soil erodibility factor map was generated using Ordinary Kriging. The spherical model has given the best model to predict spatial variability of soil erodibility which root-mean-square error and mean error values of interpolated map were very low. The range of the spatial dependency was equal to 460 m. The study basin has been classified as highly erodible and ecologically vulnerable.

<p>Phosphorus (P) is essential for plant development and to feed the world population. Most of the P that is used as a fertiliser in agriculture has a mineral origin, whose reserves are scarce as it is a non-renewable resource. Also, international conflicts add pressure to agriculture due to several reasons, for example, increasing the price of the fertilisers (including P fertilisers). At least since 2015 the European Union promotes strategies based on circular economy, and, more recently with the Mission ‘A Soil deal for Europe’, pursues to enhance soil health as this is the base of our food systems, habitats, economy, and prosperity. In Mediterranean areas of Europe, calcareous soils with a low content in organic matter and limitations in the phytoavailability of nutrients such as P and micronutrients (Fe and Zn), are predominant. For these reasons, biobased P fertilisers from wastes/residues could be an alternative to mineral P fertilisers in these soils at the same time as they could enhance soil health as they are rich in organic matter and nutrients. The objective of this study was to assess the potential of different residues (digestate from a biogas plant, compost of olive mill pomace, compost of solid urban waste, vermicompost and vegetal residues) to act as P fertilisers in calcareous soils. Diammonium phosphate (DAP) and the non-application of P were also included in the study to compare with biobased fertilziers. A field experiment was developed (randomized block-4 design) in a calcareous Vertisol in the South of Spain (Córdoba) for two years (in the traditional wheat and sunflower rotation). The different biobased P fertilisers and DAP were applied at the same rate (30 kg P ha<sup>-1</sup>) and incorporated into the arable layer of the soil (20 cm depth) before sowing durum wheat. Different analyses were done to evaluate the immediate (durum wheat) and residual (sunflower) effects of the different fertilisers: soil P and micronutrients’ availability, biomass and yield, plant nutrient uptake, soil enzyme activities, and bacterial and fungal composition in soil. The obtained results showed a good performance of the biobased fertilizers in comparison with the mineral fertiliser (DAP), i.e., wheat biomass was not negatively affected due to the application of the biobased fertilisers. In addition, the organic fertilizers had an obvious effect on the activity of soil enzymes, especially in acid phosphatase, finding the highest values in the non-P fertilised soils. The biobased P fertilizers evaluated in this study can be an efficient alternative to mineral P fertilizers in Mediterranean areas to maintain soil P availability, enhance soil functionality, provide organic matter, P and other nutrients to the plant.</p>

Soil erodibility is one of the most crucial factors used to estimate soil erosion by applying modeling techniques. Soil data from soil maps are commonly used to create maps of soil erodibility for soil conservation planning. This study analyzed the spatial variability of soil erodibility by using a digital elevation model (DTM) and surface soil sample data at the Rhirane catchment (Algeria). A total of 132 soil samples were collected of up to 20 cm in depth. The spatial distributions of the K-value and soil physical properties (permeability, organic matter, and texture) were used to elaborate ordinary Kriging interpolation maps. Results showed that mean values of soil organic matter content were statistically different between Chromic Cambisols (M = 3.4%) vs. Calcic Cambisols (M = 2.2%). The analysis of variance of the organic matter provided a tool for identifying significant differences when comparing means between the soil types. The soil granulometry is mainly composed of silt and fine sand. The soil erodibility showed values varying between 0.012 and 0.077 with an average of 0.034, which was greater in soils with calcic horizons. Statistical evaluation by using Pearson’s correlation revealed positive correlations between erodibility and silt (0.63%), and negative correlations with sand (−0.16%), clay (−0.56%), organic matter (−0.32%), permeability (−0.41%), soil structure (−0.40%), and the soil stability index (−0.26%). The variability analysis of the K-factor showed moderate spatial dependency with the soil erodibility map indicating moderate to highly erodible risk in cropland and sparse grassland land uses. Overall, the study provides scientific support for soil conservation management and appropriate agricultural food practices for food supply.