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Selenium deficiency in humans and animals can be reduced through dietary supplementation. Therefore, Se biofortification strategy is important in food plants and pastures. In this study, the effects of selenium (Se) addition (4 mg Se/kg) as sodium selenate (Na2SeO4) on lettuce (Lactuca Sativa L.) and berseem cultivation (Trifolium alexandrinum L.) were investigated. The experiment was conducted under greenhouse conditions with two different soil types, an acidic (pH = 6.3) and an alkaline (pH = 8.0) soil with different organic matter content, in a completely randomized design. The results indicated higher Se content in berseem cultivated on acidic soil. It was also observed a significant reduction (~ 45%) in plant biomass of lettuce in the acidic soil combined with Se application. The results showed that leaf Se content was negatively correlated with soil organic matter. The decreased Se content in plants cultivated on the alkaline soil with high organic matter content support that the effect of pH on Se uptake decreased as the soil organic matter content increased. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Over the last few years, phosphorus (P) has attracted the global interest because it is finite and non-renewable resource. However, some aspects of P dynamics in soils are still unclear and novel insights are necessary to better understand the very complex geochemistry of P and to conclusively evolve the traditional soil P management practices. An explicit example is the very limited research on P behavior in redoximorphic soils. These soils are characterized by specific morphological features, such as Fe-Mn concretions and nodules, and cover large areas around the world. In redoximorphic soils, biogeochemical processes change dramatically as a result of oxygen being periodically excluded from the soil environment affecting the geochemistry of nutrients and trace elements. Fe-Mn concretions and nodules are significant pedogenic components containing high amounts of Fe and Mn oxides and show high sorption capacity for various elements. This paper summarizes the current knowledge on the processes determining the formation of Fe-Mn concretions and nodules in redoximorphic soils and on their impact on soil P dynamics. Depending on soil properties, during Fe-Mn concretions and nodules formation and growth following repeated redox cycles, P can be trapped in the concretions/nodules which act as a sink for P and as a barrier to P movement from land to water bodies. Since very little scientific work on this issue has been done, intensive future work is needed to figure out the complex role of Fe-Mn concretions and nodules on P dynamics in redox-sensitive soils. © 2019 Elsevier B.V.

Toxic chromium [(Cr(VI)] in food chain has created an alarming situation for human life and ecosystems. The present study through a greenhouse pot experiment aims to (a) investigate the ability of organic matter in reducing Cr uptake by lettuce (Lactuca sativa L.) from a sandy loam soil irrigating with Cr(VI)-water, (b) to provide a way for the restriction of Cr transfer from contaminated soils and irrigation water to plants/crops and (c) to contribute to the better management of soil (land) and water use, without reduction of the agricultural production. Since soil and groundwater contamination by Cr is a potential risk in a worldwide scale, due to industrial activities and/or natural processes, organic carbon may play a key role in the mobility of added Cr(VI) to soil via irrigation water, in a significant way. The cultivation of lettuce, using organic matter in the form of leonardite (10 and 30 wt%) and Cr(VI)-irrigation water (100, 200 and 300 mgL−1), showed that the uptake of Cr in both shoots and roots increased with increasing concentration of Cr in the irrigation water. The highest Cr values in shoots (average = 10 mg/kg) and in roots (average = 28 mg/kg) were recorded in those plants cultivated in soil after the addition of Cr(VI)- water without organic matter, whereas the lowest Cr values in shoots (average = 0.44 mg/kg) and in roots (average = 0.7 mg/kg) were recorded in those plants cultivated in soil with addition of 30 wt% organic matter. The used leonardite as organic matter that is an oxidized form of lignite, due to its high content of humic acid is considered to be a useful organic fertilizer that provides possibilities for combining food production with soil protection. Therefore, the application of the natural organic material leonardite, as a land management technique, seems to be a cost-effective method consistent to related protocols for the protection of the soil quality. © 2018 Elsevier Ltd

Organic farming has expanded rapidly in Europe over the last decade due to environmental, economic and social concerns. A comparative study of organic and conventional apple orchard management systems was conducted in order to compares Fe, Mn, Cu and Zn availability in soil as well as to evaluate the concentration of micronutrients in the leaves of apple trees. The soil in both orchards was characterized as a clay loam – clay soil and was very uniform in morphological and physical properties suggesting that any differences in the measured soil parameters may be attributed to the management system and not to soil heterogeneity. The soil of the organically cultivated orchard exhibited significantly lower Cu and Zn concentrations than that of the conventional one. The application of various agrochemicals like pesticides and synthetic fertilizers in the conventionally managed soils seems to increase the content of these metals. In addition the results of this study indicated that the type as well as the application rate of inputs of organic matter in the organically management orchard are insufficient in order to increase the availability of metals in soil. All leaf nutrients were within the sufficiency range in both management systems. The orchard management system had a significant effect on the concentration of Cu and Zn in apple leaves while time of sampling had a significant effect on almost all measured nutrients, except from Mn. Copper concentration was significantly higher in leaves of the organically cultivated orchard, especially during the last two sampling events probably to the extent use of many copper-containing fungicides in organic orchards in Greece.

Under greenhouse conditions a pot experiment was carried out to investigate the comparative interaction of Cs and K in the shoots of plants, and to interpret the way that K+ ions related to that of Cs+ in soil-plant systems. Also the soil properties that affect Cs uptake by Trifolium pratense plants were determined. The plants grown on four different soil types, contaminated with 40 mg kg-1 of Cs, and sown at 60, 240 and 420 days after contamination (treatments). During each treatment two cuts of the shoots were performed. According to the results significantly variations on Cs uptake by Trifolium pratense plants observed among different cuts, soil types and treatments. Regardless to soil type or treatment, it was found that as the concentration of Cs decreased, the K content increased in shoots in both plant cuts. Such relationship, confirms the occurrence of a direct competition between Cs and K ions during the process of accumulation through the plant tissues, suggesting that the two elements could have a common accumulation mechanism and that Cs uptake by plants can be suppressed by the competition of Cs and K ions in the plant tissues. Due to the competitive interactions that occurred between Cs and K ions, the discrimination factor (DF), which is often used to evaluate plant's efficiency to absorb nutrients from soil, was additionally estimated. In all treatments DF values were below unity, suggesting a preferential uptake of K over Cs. Thus, K appears to be one of the main factors influencing the plant mobility of Cs and behaves not only as a competitor to Cs ions, but also as an effective inhibitor of Cs uptake by plants. Among the soil properties it was observed that the particle size fractions as well as the K content in soils play a predominant role on Cs availability to plants. Thus, Cs uptake by plants is a result of reactions both in the soil and in the plant, implying that Cs transport from soil to plant is controlled by a complex mechanism. Therefore the utilization of the K-status of plant tissues simultaneously with the soil properties is essential to monitor and estimate soil to plant Cs mobility.