Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations.

Leaves of olive (Olea europaea var. minor rotunda) were collected from mature non-irrigated trees in an “off” year, at monthly intervals, from May 2015 to April 2016. Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and boron (B) were determined. Seasonal fluctuation curves were developed for each nutrient, in order to use them for interpretation of leaf analysis. Concentrations of N, P, K, Ca and Mg showed significant fluctuation throughout the year, while B, Fe, Mn and Zn showed less intense changes. Nutrient accumulation varied according to tree vegetative growth and weather conditions.

Nowadays, the estimation of volumetric soil water content (θ) through apparent dielectric permittivity (ε_a) is the most widely used method. The purpose of this study is to investigate the effect of the high iron content of two sandy loam soils on estimating their water content using two dielectric sensors. These sensors are the WET sensor operating at 20 MHz and the ML2 sensor operating at 100 MHz. Experiments on specific soil columns, in the laboratory, by mixing different amounts of water in the soils to obtain a range of θ values under constant temperature conditions were conducted. Analysis of the results showed that both sensors, based on manufacturer calibration, led to overestimation of θ. This overestimation is due to the high measured values of ε_a by both sensors used. The WET sensor, operating at a lower frequency and being strongly affected by soil characteristics, showed the greatest overestimation. The difference of ε_a values between the two sensors ranged from 14 to 19 units at the maximum actual soil water content (θ_m). Compared to the Topp equation, the WET sensor measures 2.3 to 2.8 fold higher value of ε_a. From the results, it was shown that the relationship θ_m-ε_a^0.5 remained linear even in the case of these soils with high iron content and the multi-point calibration (CALALL) is a good option where individual calibration is needed.

Two soil mapping methodologies at different scales applied in the same area were compared in order to investigate the potential of their combined use to achieve an integrated and more accurate soil description for sustainable land use management. The two methodologies represent the main types of soil mapping systems used and still applied in soil surveys in Greece. Diomedes Botanical Garden (DBG) (Athens, Greece) was used as a study area because past cartographic data of soil survey were available. The older soil survey data were obtained via the conventional methodology extensively used over time since the beginnings of soil mapping in Greece (1977). The second mapping methodology constitutes the current soil mapping system in Greece recently used for compilation of the national soil map. The obtained cartographic and soil data resulting from the application of the two methodologies were analyzed and compared using appropriate geospatial techniques. Even though the two mapping methodologies have been performed at different mapping scales, using partially different mapping symbols and different soil classification systems, the description of the soils based on the cartographic symbols of the two methodologies presented an agreement of 63.7% while the soil classification by the two taxonomic systems namely Soil Taxonomy and World Reference Base for Soil Resources had an average coincidence of 69.5%.

Leaf samples from mature olive (Olea europaea L. cv. 'Kalamon') trees were collected monthly from April 2018 to March 2019 from two olive orchards, cultivated one in acid and one in alkaline soil, located in Western Greece. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) concentrations in the leaves were determined and seasonal variation curves were calculated for each nutrient and orchard. The seasonal concentration patterns of N, P, K, Ca, and Mg nutrients were almost similar in both soils. Seasonal variation nutrient curves independently of soil acidity varied according to vegetation stages and no significant differences in nutrient concentrations were observed at different development stages between olives grown in the acid or the alkaline soils, with only one exception the leaf K concentration. The nutrient concentration measured in wintertime was at a sufficient level for optimum olive growth in both orchards. These concentrations could be used as reference values for leaf analysis interpretation and for developing an optimum fertilization program under Mediterranean climatic conditions.