Dionisios Gasparatos | Agricultural University of Athens (original) (raw)

Papers by Dionisios Gasparatos

Environmental Science and Pollution Research

In the present study, the ability of a modified CaCl2 zeolite (Ca-Z) to both increase Se(IV) avai... more In the present study, the ability of a modified CaCl2 zeolite (Ca-Z) to both increase Se(IV) availability and restrict Se(VI) mobility in soils is examined. As it was resulted from batch experiments and verified by X-ray absorption fine structure (XAFS) and X-ray fluorescence (XRF) spectroscopies, higher amounts of both Se species adsorbed on Ca-Z compared to natural zeolite (Z-N) forming outer-sphere complexes while the oxidation state did not alter during agitation of samples. Thereafter, Ca-Z was incorporated in six Greek soils, divided into acid and alkaline, at a 20% (w/w) rate and a series of equilibrium batch experiments were performed with soils alone and soils-Ca-Z mixtures to investigate sorption and desorption processes and mechanisms. The acid soils, either treated with Ca-Z or not, adsorbed higher amounts of Se(IV) than alkaline ones, whereas soils alone did not adsorb Se(VI) but impressively high adsorption of Se(VI) occurred in the Ca-Z-treated soils. Desorption of Se...

Agronomy, 2022

Selenium biofortification of lettuce plants was studied for two rates (5 and 10 mg kg−1 soil) of ... more Selenium biofortification of lettuce plants was studied for two rates (5 and 10 mg kg−1 soil) of either selenate or selenite and for the effect of 5% w/w biochar addition. Lettuce seedlings were grown in pots containing 1 kg of a calcareous soil. Twelve weeks later, the plants were harvested and selenium (Se), phosphorus (P), and sulfur (S) concentrations were determined in heads and roots. Plant growth characteristics were measured and plant biometrics were assessed by NDVI, NDRE, and SPAD measurements. The highest Se concentration of 315.19 mg kg−1 D.W. and the highest amount of Se taken up by plants (950.5 μg/pot) were observed for the low selenate rate with biochar. The corresponding values for selenite treatments were an order of magnitude lower. Although in general, minor to severe toxicity symptoms occurred with selenium application in no biochar treatments (except selenite low rate), the addition of biochar secured plant growth and increased S and P concentrations in plants,...

Environmental Science and Pollution Research, 2019

Application of chelating and reductive agents in soils can increase the availability of potential... more Application of chelating and reductive agents in soils can increase the availability of potentially toxic elements facilitating their uptake by plants. This study discusses the effect of single or combined EDTA (E), sodium dithionite (SD), and olive mill wastewater (OMW) treatments on As, Pb, and Zn mobility over time in a heavily contaminated mine-affected soil. Soil samples were incubated for 1, 3, 7, 15, 30, 60, and 90 days and at each incubation time the easily mobilizable fraction obtained by (NH 4 ) 2 SO 4 (for As) and CH 3 COOH (for Pb/Zn). The results showed that the highest availability of As (mean value 41 mg kg −1 ) was observed for the EDTA treatment followed by E+OMW (mean value 32 mg kg −1 ) and E+SD+OMW (mean value 27 mg kg −1 ). For Pb and Zn, significantly higher available concentrations were obtained by the EDTA and E+OMW treatments (mean values 2532 mg kg −1 and 1427 mg kg −1 for Pb and Zn respectively) followed by the E+SD (mean value 2259 and 1333 mg kg −1 for Pb and Zn) and E+SD+OMW treatments (mean value 2388 and 1340 mg kg −1 for Pb and Zn). Moreover, the incubated for 90 days soil samples subjected to two different sequential extraction protocols (SEPs): Wenzel (for As) and BCR (for Pb, Zn, Fe, and Mn). The results showed that As, Pb, and Zn mobility was mainly regulated by the amorphous Fe oxides. Our findings suggest that OMW application in soils should focus more attention since when combined with other amendments produced contradictory results.

Journal of Soil Science and Plant Nutrition

Aiming at the production of robust chestnut plants suitable for the establishment of plantations ... more Aiming at the production of robust chestnut plants suitable for the establishment of plantations or for their use in afforestation of forest ecosystems, we studied the effect of soil mixtures on growth, physiological characteristics, and nutritional status of chestnut seedlings. In a complete randomized-block design pot experiment, the soil used was derived from gneiss weathering (GN) and the treatments included GN and GN with fertilization (GN-FER) as well as mixtures of GN with forest floor (FF) from chestnuts (GN-CFF) and from evergreen broad-leaved trees (GN-EFF). Both types of forest floor and fertilization had similar positive effect on seedlings growth and photosynthetic parameters. The most significant effects on soil nutrients were found in GN-CFF and GN-EFF treatments, except for extractable phosphorus (P) and exchangeable potassium (K), whose highest concentrations were observed in GN-FER. Leaf analysis showed that the concentrations of almost all nutrients in all treatme...

Agronomy

This work investigates the effects of an organic fertilizer enriched in Ca and Mg and two bacteri... more This work investigates the effects of an organic fertilizer enriched in Ca and Mg and two bacterial inoculants, applied alone and in combination, on soil fertility, plant growth, nutrition, and production of secondary metabolites, namely, acemannan and total phenolic compounds (TPCs), by Aloe vera (Aloe barbadensis Miller), under field cultivation. The first inoculum consisted of five native bacterial strains (Pseudomonas sp., Enterobacter sp., and three strains of Pantoea sp.), characterized in vitro as putative plant growth promoters, isolated from local organic farming fields of Aloe vera. The second inoculant was a commercial product (BACTILIS-S and HUMOFERT) and consisted of three Bacillus species: B. pumilus, B. amyloliquefaciens, and B. subtilis. The organic fertilizer (HUMO-CAL M-8O) was a mixture of humic and fulvic acids, with an additional CaCO3 (40% w/w) and MgO (4% w/w). The most significant increase in the content of acemannan and TPCs was detected under single applica...

The dependence of all life on phosphorus (P) availability has revealed serious P challenges such ... more The dependence of all life on phosphorus (P) availability has revealed serious P challenges such as the P deficiency in weathered and eroded soils, the high cost of phosphate fertilizers, the scarcity and unequal global distribution of rock phosphates, the regional over-accumulation of P and the agricultural non-point source P pollution. In this context, microorganisms capable of mobilizing P in the soil system may be applied as a low-cost technology to enhance plant growth and crop yields. Here we review the beneficial role of microorganisms, namely arbuscular mycorrhizal fungi and P–mobilizing bacteria, to mediate P availability and transform legacy P (insoluble, bound) into soluble forms.

Land

Copper-contained products that are widely employed yearly in viticulture for vine disease managem... more Copper-contained products that are widely employed yearly in viticulture for vine disease management, lead to Cu accumulation in topsoil creating an increased risk for land workers and for leaching and/or uptake of Cu by plants, especially in acidic soils where Cu mobility is higher. In this study, the impact of two biochar types on Cu distribution and redistribution in fractions was evaluated in four acidic vineyard soils in relation to incubation time. The two biochars were derived from sewage sludge (SG) and olive tree prunings (OL). Soils (control) and biochar-amended soils with application rate of 20 % (w/w) were spiked with CuCl2 (160 mg kg−1) and incubated in the laboratory at ambient temperature 22 ± 5 °C. After 1, 3, 7, 15, 36, and 90 days of incubation, modified BCR sequential extraction procedure was used to determine Cu distribution in the four soil chemical phases and to examine potential Cu redistribution between these fractions both in soils and in amended soils with ...

Nickel in Soils and Plants, 2018

D.L. Bouranis1*, D. Argyros3, G. Georgoulas3, D. Petrakos3, A. Varnas3, D. Gasparatos2, M. Marget... more D.L. Bouranis1*, D. Argyros3, G. Georgoulas3, D. Petrakos3, A. Varnas3, D. Gasparatos2, M. Margetis1, F. Maniou1, S.N. Chorianopoulou1, H. Mavrogiannis3 and D. Benardos3 1Plant Physiology and Morphology Laboratory, Crop Science Department, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece (E-mail: bouranis@aua.gr); 2Soil Science Laboratory, Department of Hydraulics, Soil Science and Agricultural Engineering, School of Agriculture, Faculty of Agriculture, Forestry and Natural Environment, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; 3Sulphur Hellas S.A., Leoforos Athinon 142, 104 42 Athens, Greece

Science of The Total Environment

The established practices of intensive agriculture, combined with inadequate soil Κ replenishment... more The established practices of intensive agriculture, combined with inadequate soil Κ replenishment by conventional inorganic fertilization, results in a negative environmental impact through the gradual exhaustion of different forms of K reserves in soils. Although biochar application as soil amendment has been established as an approach of integrated nutrient management, few works have focused on the impact of biochar application to soil K availability and crop uptake. This review provides an up-to-date analysis of the published literature, focusing on the impact of biochar in the availability of potassium in soil and crop growth. First, the effect of biomass type and pyrolysis temperature on potassium content of biochar was assessed. Second, the influence of biochar addition to the availability of potassium in soil and on potassium soil dynamics was examined. Finally, alternative methods for estimating available K in soils were proposed. The most promising biomasses in terms of potassium content were grape pomace, coffee husk and hazelnut husk however, these have not been widely utilized for biochar production. Higher pyrolysis temperatures (>500 °C) increase the total potassium content whereas lower temperatures increase the water-soluble and exchangeable potassium fractions. It was also determined that biochar has considerable potential for enhancing K availability through several distinct mechanisms which eventually lead directly or indirectly to increased K uptake by plants. Indirect mechanisms mainly include increased K retention capacity based on biochar properties such as high cation exchange capacity, porosity, and specific surface area, while the direct supply of K can be provided by K-rich biochar sources through purpose-made biochar production techniques. Research based on biochar applications for soil K fertility purposes is still at an early stage, therefore future work should focus on elucidating the mechanisms that define K retention and release processes through the complicated soil-biochar-plant system.

Science of the Total Environment, 2023

The established practices of intensive agriculture, combined with inadequate soil Κ replenishment... more The established practices of intensive agriculture, combined with inadequate soil Κ replenishment by conventional inorganic fertilization, results in a negative environmental impact through the gradual exhaustion of different forms of K reserves in soils. Although biochar application as soil amendment has been established as an approach of integrated nutrient management, few works have focused on the impact of biochar application to soil K availability and crop uptake. This review provides an up-to-date analysis of the published literature, focusing on the impact of biochar in the availability of potassium in soil and crop growth. First, the effect of biomass type and pyrolysis temperature on potassium content of biochar was assessed. Second, the influence of biochar addition to the availability of potassium in soil and on potassium soil dynamics was examined. Finally, alternative methods for estimating available K in soils were proposed. The most promising biomasses in terms of potassium content were grape pomace, coffee husk and hazelnut husk however, these have not been widely utilized for biochar production. Higher pyrolysis temperatures (>500 °C) increase the total potassium content whereas lower temperatures increase the water-soluble and exchangeable potassium fractions. It was also determined that biochar has considerable potential for enhancing K availability through several distinct mechanisms which eventually lead directly or indirectly to increased K uptake by plants. Indirect mechanisms mainly include increased K retention capacity based on biochar properties such as high cation exchange capacity, porosity, and specific surface area, while the direct supply of K can be provided by K-rich biochar sources through purpose-made biochar production techniques. Research based on biochar applications for soil K fertility purposes is still at an early stage, therefore future work should focus on elucidating the mechanisms that define K retention and release processes through the complicated soil-biochar-plant system.

Bulletin of the Geological Society of Greece, 2017

Soils are receptors of atmospheric metal depositions and hence reliable indicators of pollution p... more Soils are receptors of atmospheric metal depositions and hence reliable indicators of pollution phenomena, especially for cases that potential site specific pollution sources are detected in terrestrial ecosystems. The purpose of this study was to assess the distribution of Cu, Zn, Fe, Mn, Ni, Cr, Pb, and Ba concentrations in soils nearby the International Athens Airport “El. Venizelos”, in Attica, Greece. Total metal concentrations were determined in 86 topsoil aqua regia extracts and the median values for Cu, Zn, Fe, Mn, Ni, Cr, Pb, and Ba concentrations were 23, 81, 22x103 , 497, 87, 74, 75, and 423 mg kg-1 respectively. Though median values are not considered as high, the 90th percentile concentration values for some metals are high, indicating possible soil enrichment by these metals. A tendency for increased concentrations of Zn and Cr along the north-south axis and of Pb, Cu and Ni at the northern part of the studied area was also observed. As a first approach to discriminate...

Applied Sciences

This study, based on circular economy principles and sustainable development practices, aims to p... more This study, based on circular economy principles and sustainable development practices, aims to present the results of soil samples analysis after their mixture with a biobed bio-mixture of straw, soil and compost, used for two consecutive years as organic bio-filter of olive oil mill wastewater. So far, exhausted bio-mixtures used in biobeds to minimize pesticide point-source contamination turned out to contain residues of pesticides, and they are considered hazardous wastes; thus, they require special treatment before their disposal. Contrariwise, saturated bio-mixtures from bio-bed systems utilized for olive mill wastewater (OMWW) treatment not only do not require any special treatment before their final disposal but also can be exploited as a soil amendment. To this end, the effects of the used bio-mixture application in three different proportions as a soil amendment on the physical and chemical properties of medium-texture soil were investigated. The application of water simul...

Soil Systems

To tackle selenium (Se) malnutrition, biofortification is among the proposed strategies. A biosti... more To tackle selenium (Se) malnutrition, biofortification is among the proposed strategies. A biostimulant application in soils is thought to support a plant’s growth and productivity. Biofortification with Se(VI) may lead to a leaching hazard due to the high mobility of Se(VI) in the soil environment. In this study, the effect of the application of two Se(VI) rates—5 and 10 mg kg−1 soil—and a biostimulant on the Se uptake by lettuce plants and on the Se(VI) distribution in soil fractions following the plants’ harvest, was investigated. Phosphorus (P) and sulfur (S) concentrations in plants were also determined. A high Se(VI) rate suppressed plant growth, leading to a significant fresh weight decrease from 12.28 to 7.55 g and from 14.6 to 2.43 g for the control and high Se(VI) without and with biostimulants, respectively. Impaired plant growth was verified by the SPAD, NDVI and NDRE measurements. The significantly highest Se concentration in plants, 325 mg kg−1, was recorded for the hi...

Environments

Soils close to former mines or metallurgical facilities often contain extreme concentrations of p... more Soils close to former mines or metallurgical facilities often contain extreme concentrations of potentially toxic elements (PTEs), and among soil remediation actions needed, enhanced phytoextraction techniques using chelating agents could be a very promising option. In this context, a pot experiment was conducted to evaluate the effect of Na2-EDTA, olive mill wastewater (OMW), and their combination (EDTA + OMW) on As, Pb and Zn uptake by Helianthus annuus (sunflower), grown in a heavily contaminated soil from Lavrio, Greece. After harvest, aboveground and belowground biomass and the concentrations of As, Pb and Zn were determined. Additionally, composite soil samples of all treatments were subjected to appropriate sequential extraction procedures for each PTE. Results showed that although nonstatistically significant effects on plant growth and As concentration were observed, Pb and Zn plant concentrations increased by the EDTA addition, alone or combined with OMW. When the total bi...

Parlar Scientific Publications, 2017

In calcareous soils, Fe availability is highly restricted. On the other hand, Fe metabolism is in... more In calcareous soils, Fe availability is highly restricted. On the other hand, Fe metabolism is intimately related to S, N, and P ones, whilst intensive agronomic activity requires significant S inputs. How these relationships are shaped in the commonly used for lawns species Cynodon dactylon, Pennisetum clandestinum, Festuca arundinacea, Festuca rubra, Lolium perenne, Poa pratensis, Dichondra repens, and Trifolium repens, when they are grown in a medium-textured calcareous soil irrigated with slightly saline water? In this system, [Sorg] presented a wide range among the studied lawns, and two groups were distinguished: one with [Sorg] above 70 μmol g-1 DM and the other with [Sorg] below 50 μmol g-1 DM. All binary combinations of N/Sorg, P/Sorg, SO4 2-/Sorg, Fe/Sorg ratios were in very strong linear relationships, along with N/Fe vs P/Fe ratios. Sorg/Fe ratio suggested more acquisition of S relative to Fe, by the warm season grasses. The relationship between Sorg/Fe and SO4 2-/Sorg ratios suggested that Fe and SO4 2-were interconnected via the required content of Sorg and the following scenario seems to be supported: P nutrition was adjusted to N nutrition; iron was adjusted to both of them, so that N/Fe was in linear relationship to P/Fe. Sorg was adapted to both N and Fe.

Journal of Plant Nutrition, 2019

Olive is the most important fruit tree species grown in Mediterranean basin, where many times it ... more Olive is the most important fruit tree species grown in Mediterranean basin, where many times it grows under saline conditions, due to irrigation with low quality water. Olive response to salinity is cultivar dependent and the evaluation of native genotypes is an important tool in finding tolerant genetic material. For this reason, five Greek olive cultivars, i.e. "Koroneiki", "Gaidourelia", "Lefkolia Serron", "N-K Gigas" and "Throumbolia", were evaluated regarding their tolerance to sodium chloride salinity (0, 50, 100 and 200 mM). All cultivars exhibited a significant reduction of growth, while the most severe symptoms were found in "Gaidourelia" while "Lefkolia Serron" presented the least symptoms. The latter exhibited the lowest sodium concentration in the leaves and the highest in the roots. Both potassium to sodium and calcium to sodium ratios were high in "Gaidourelia" leaves and stems, suggesting that the use of nutrient concentration for comparison of olive tolerance among cultivars could lead to erroneous results. The best indicator proved to be the determination of nutrient relative concentration compared to corresponding cultivar's control, as "Gaidourelia" exhibited the highest sodium relative concentration as well as the lowest nutrient ratios, revealing its inability to restrain sodium in the root level.

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Environments

Selenium adsorption/desorption behavior was examined for eight Greek top soils with different pro... more Selenium adsorption/desorption behavior was examined for eight Greek top soils with different properties, aiming to describe the geochemistry of the elements in the selected soils in terms of bioavailability and contamination risk by leaching. Four soils were acid and four alkaline, and metal oxides content greatly differed between the two groups of soils. The concentrations of Se(IV) used for the performed adsorption batch experiments ranged from 1 to 50 mg/L, while the soil to solution ratio was 1 g/0.03 L. Acid soils adsorbed significantly higher amounts of the added Se(IV) than alkaline soils. Freundlich and Langmuir equations adequately described the adsorption of Se(IV) in the studied soils, and the parameters of both isotherms significantly correlated with soil properties. In particular, both KF and qm values significantly positively correlated with ammonium oxalate extractable Fe and with dithionite extractable Al and Mn, suggesting that amorphous Fe oxides and Al and Mn oxi...

Environmental Science and Pollution Research

In the present study, the ability of a modified CaCl2 zeolite (Ca-Z) to both increase Se(IV) avai... more In the present study, the ability of a modified CaCl2 zeolite (Ca-Z) to both increase Se(IV) availability and restrict Se(VI) mobility in soils is examined. As it was resulted from batch experiments and verified by X-ray absorption fine structure (XAFS) and X-ray fluorescence (XRF) spectroscopies, higher amounts of both Se species adsorbed on Ca-Z compared to natural zeolite (Z-N) forming outer-sphere complexes while the oxidation state did not alter during agitation of samples. Thereafter, Ca-Z was incorporated in six Greek soils, divided into acid and alkaline, at a 20% (w/w) rate and a series of equilibrium batch experiments were performed with soils alone and soils-Ca-Z mixtures to investigate sorption and desorption processes and mechanisms. The acid soils, either treated with Ca-Z or not, adsorbed higher amounts of Se(IV) than alkaline ones, whereas soils alone did not adsorb Se(VI) but impressively high adsorption of Se(VI) occurred in the Ca-Z-treated soils. Desorption of Se...

Agronomy, 2022

Selenium biofortification of lettuce plants was studied for two rates (5 and 10 mg kg−1 soil) of ... more Selenium biofortification of lettuce plants was studied for two rates (5 and 10 mg kg−1 soil) of either selenate or selenite and for the effect of 5% w/w biochar addition. Lettuce seedlings were grown in pots containing 1 kg of a calcareous soil. Twelve weeks later, the plants were harvested and selenium (Se), phosphorus (P), and sulfur (S) concentrations were determined in heads and roots. Plant growth characteristics were measured and plant biometrics were assessed by NDVI, NDRE, and SPAD measurements. The highest Se concentration of 315.19 mg kg−1 D.W. and the highest amount of Se taken up by plants (950.5 μg/pot) were observed for the low selenate rate with biochar. The corresponding values for selenite treatments were an order of magnitude lower. Although in general, minor to severe toxicity symptoms occurred with selenium application in no biochar treatments (except selenite low rate), the addition of biochar secured plant growth and increased S and P concentrations in plants,...

Environmental Science and Pollution Research, 2019

Application of chelating and reductive agents in soils can increase the availability of potential... more Application of chelating and reductive agents in soils can increase the availability of potentially toxic elements facilitating their uptake by plants. This study discusses the effect of single or combined EDTA (E), sodium dithionite (SD), and olive mill wastewater (OMW) treatments on As, Pb, and Zn mobility over time in a heavily contaminated mine-affected soil. Soil samples were incubated for 1, 3, 7, 15, 30, 60, and 90 days and at each incubation time the easily mobilizable fraction obtained by (NH 4 ) 2 SO 4 (for As) and CH 3 COOH (for Pb/Zn). The results showed that the highest availability of As (mean value 41 mg kg −1 ) was observed for the EDTA treatment followed by E+OMW (mean value 32 mg kg −1 ) and E+SD+OMW (mean value 27 mg kg −1 ). For Pb and Zn, significantly higher available concentrations were obtained by the EDTA and E+OMW treatments (mean values 2532 mg kg −1 and 1427 mg kg −1 for Pb and Zn respectively) followed by the E+SD (mean value 2259 and 1333 mg kg −1 for Pb and Zn) and E+SD+OMW treatments (mean value 2388 and 1340 mg kg −1 for Pb and Zn). Moreover, the incubated for 90 days soil samples subjected to two different sequential extraction protocols (SEPs): Wenzel (for As) and BCR (for Pb, Zn, Fe, and Mn). The results showed that As, Pb, and Zn mobility was mainly regulated by the amorphous Fe oxides. Our findings suggest that OMW application in soils should focus more attention since when combined with other amendments produced contradictory results.

Journal of Soil Science and Plant Nutrition

Aiming at the production of robust chestnut plants suitable for the establishment of plantations ... more Aiming at the production of robust chestnut plants suitable for the establishment of plantations or for their use in afforestation of forest ecosystems, we studied the effect of soil mixtures on growth, physiological characteristics, and nutritional status of chestnut seedlings. In a complete randomized-block design pot experiment, the soil used was derived from gneiss weathering (GN) and the treatments included GN and GN with fertilization (GN-FER) as well as mixtures of GN with forest floor (FF) from chestnuts (GN-CFF) and from evergreen broad-leaved trees (GN-EFF). Both types of forest floor and fertilization had similar positive effect on seedlings growth and photosynthetic parameters. The most significant effects on soil nutrients were found in GN-CFF and GN-EFF treatments, except for extractable phosphorus (P) and exchangeable potassium (K), whose highest concentrations were observed in GN-FER. Leaf analysis showed that the concentrations of almost all nutrients in all treatme...

Agronomy

This work investigates the effects of an organic fertilizer enriched in Ca and Mg and two bacteri... more This work investigates the effects of an organic fertilizer enriched in Ca and Mg and two bacterial inoculants, applied alone and in combination, on soil fertility, plant growth, nutrition, and production of secondary metabolites, namely, acemannan and total phenolic compounds (TPCs), by Aloe vera (Aloe barbadensis Miller), under field cultivation. The first inoculum consisted of five native bacterial strains (Pseudomonas sp., Enterobacter sp., and three strains of Pantoea sp.), characterized in vitro as putative plant growth promoters, isolated from local organic farming fields of Aloe vera. The second inoculant was a commercial product (BACTILIS-S and HUMOFERT) and consisted of three Bacillus species: B. pumilus, B. amyloliquefaciens, and B. subtilis. The organic fertilizer (HUMO-CAL M-8O) was a mixture of humic and fulvic acids, with an additional CaCO3 (40% w/w) and MgO (4% w/w). The most significant increase in the content of acemannan and TPCs was detected under single applica...

The dependence of all life on phosphorus (P) availability has revealed serious P challenges such ... more The dependence of all life on phosphorus (P) availability has revealed serious P challenges such as the P deficiency in weathered and eroded soils, the high cost of phosphate fertilizers, the scarcity and unequal global distribution of rock phosphates, the regional over-accumulation of P and the agricultural non-point source P pollution. In this context, microorganisms capable of mobilizing P in the soil system may be applied as a low-cost technology to enhance plant growth and crop yields. Here we review the beneficial role of microorganisms, namely arbuscular mycorrhizal fungi and P–mobilizing bacteria, to mediate P availability and transform legacy P (insoluble, bound) into soluble forms.

Land

Copper-contained products that are widely employed yearly in viticulture for vine disease managem... more Copper-contained products that are widely employed yearly in viticulture for vine disease management, lead to Cu accumulation in topsoil creating an increased risk for land workers and for leaching and/or uptake of Cu by plants, especially in acidic soils where Cu mobility is higher. In this study, the impact of two biochar types on Cu distribution and redistribution in fractions was evaluated in four acidic vineyard soils in relation to incubation time. The two biochars were derived from sewage sludge (SG) and olive tree prunings (OL). Soils (control) and biochar-amended soils with application rate of 20 % (w/w) were spiked with CuCl2 (160 mg kg−1) and incubated in the laboratory at ambient temperature 22 ± 5 °C. After 1, 3, 7, 15, 36, and 90 days of incubation, modified BCR sequential extraction procedure was used to determine Cu distribution in the four soil chemical phases and to examine potential Cu redistribution between these fractions both in soils and in amended soils with ...

Nickel in Soils and Plants, 2018

D.L. Bouranis1*, D. Argyros3, G. Georgoulas3, D. Petrakos3, A. Varnas3, D. Gasparatos2, M. Marget... more D.L. Bouranis1*, D. Argyros3, G. Georgoulas3, D. Petrakos3, A. Varnas3, D. Gasparatos2, M. Margetis1, F. Maniou1, S.N. Chorianopoulou1, H. Mavrogiannis3 and D. Benardos3 1Plant Physiology and Morphology Laboratory, Crop Science Department, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece (E-mail: bouranis@aua.gr); 2Soil Science Laboratory, Department of Hydraulics, Soil Science and Agricultural Engineering, School of Agriculture, Faculty of Agriculture, Forestry and Natural Environment, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; 3Sulphur Hellas S.A., Leoforos Athinon 142, 104 42 Athens, Greece

Science of The Total Environment

The established practices of intensive agriculture, combined with inadequate soil Κ replenishment... more The established practices of intensive agriculture, combined with inadequate soil Κ replenishment by conventional inorganic fertilization, results in a negative environmental impact through the gradual exhaustion of different forms of K reserves in soils. Although biochar application as soil amendment has been established as an approach of integrated nutrient management, few works have focused on the impact of biochar application to soil K availability and crop uptake. This review provides an up-to-date analysis of the published literature, focusing on the impact of biochar in the availability of potassium in soil and crop growth. First, the effect of biomass type and pyrolysis temperature on potassium content of biochar was assessed. Second, the influence of biochar addition to the availability of potassium in soil and on potassium soil dynamics was examined. Finally, alternative methods for estimating available K in soils were proposed. The most promising biomasses in terms of potassium content were grape pomace, coffee husk and hazelnut husk however, these have not been widely utilized for biochar production. Higher pyrolysis temperatures (>500 °C) increase the total potassium content whereas lower temperatures increase the water-soluble and exchangeable potassium fractions. It was also determined that biochar has considerable potential for enhancing K availability through several distinct mechanisms which eventually lead directly or indirectly to increased K uptake by plants. Indirect mechanisms mainly include increased K retention capacity based on biochar properties such as high cation exchange capacity, porosity, and specific surface area, while the direct supply of K can be provided by K-rich biochar sources through purpose-made biochar production techniques. Research based on biochar applications for soil K fertility purposes is still at an early stage, therefore future work should focus on elucidating the mechanisms that define K retention and release processes through the complicated soil-biochar-plant system.

Science of the Total Environment, 2023

The established practices of intensive agriculture, combined with inadequate soil Κ replenishment... more The established practices of intensive agriculture, combined with inadequate soil Κ replenishment by conventional inorganic fertilization, results in a negative environmental impact through the gradual exhaustion of different forms of K reserves in soils. Although biochar application as soil amendment has been established as an approach of integrated nutrient management, few works have focused on the impact of biochar application to soil K availability and crop uptake. This review provides an up-to-date analysis of the published literature, focusing on the impact of biochar in the availability of potassium in soil and crop growth. First, the effect of biomass type and pyrolysis temperature on potassium content of biochar was assessed. Second, the influence of biochar addition to the availability of potassium in soil and on potassium soil dynamics was examined. Finally, alternative methods for estimating available K in soils were proposed. The most promising biomasses in terms of potassium content were grape pomace, coffee husk and hazelnut husk however, these have not been widely utilized for biochar production. Higher pyrolysis temperatures (>500 °C) increase the total potassium content whereas lower temperatures increase the water-soluble and exchangeable potassium fractions. It was also determined that biochar has considerable potential for enhancing K availability through several distinct mechanisms which eventually lead directly or indirectly to increased K uptake by plants. Indirect mechanisms mainly include increased K retention capacity based on biochar properties such as high cation exchange capacity, porosity, and specific surface area, while the direct supply of K can be provided by K-rich biochar sources through purpose-made biochar production techniques. Research based on biochar applications for soil K fertility purposes is still at an early stage, therefore future work should focus on elucidating the mechanisms that define K retention and release processes through the complicated soil-biochar-plant system.

Bulletin of the Geological Society of Greece, 2017

Soils are receptors of atmospheric metal depositions and hence reliable indicators of pollution p... more Soils are receptors of atmospheric metal depositions and hence reliable indicators of pollution phenomena, especially for cases that potential site specific pollution sources are detected in terrestrial ecosystems. The purpose of this study was to assess the distribution of Cu, Zn, Fe, Mn, Ni, Cr, Pb, and Ba concentrations in soils nearby the International Athens Airport “El. Venizelos”, in Attica, Greece. Total metal concentrations were determined in 86 topsoil aqua regia extracts and the median values for Cu, Zn, Fe, Mn, Ni, Cr, Pb, and Ba concentrations were 23, 81, 22x103 , 497, 87, 74, 75, and 423 mg kg-1 respectively. Though median values are not considered as high, the 90th percentile concentration values for some metals are high, indicating possible soil enrichment by these metals. A tendency for increased concentrations of Zn and Cr along the north-south axis and of Pb, Cu and Ni at the northern part of the studied area was also observed. As a first approach to discriminate...

Applied Sciences

This study, based on circular economy principles and sustainable development practices, aims to p... more This study, based on circular economy principles and sustainable development practices, aims to present the results of soil samples analysis after their mixture with a biobed bio-mixture of straw, soil and compost, used for two consecutive years as organic bio-filter of olive oil mill wastewater. So far, exhausted bio-mixtures used in biobeds to minimize pesticide point-source contamination turned out to contain residues of pesticides, and they are considered hazardous wastes; thus, they require special treatment before their disposal. Contrariwise, saturated bio-mixtures from bio-bed systems utilized for olive mill wastewater (OMWW) treatment not only do not require any special treatment before their final disposal but also can be exploited as a soil amendment. To this end, the effects of the used bio-mixture application in three different proportions as a soil amendment on the physical and chemical properties of medium-texture soil were investigated. The application of water simul...

Soil Systems

To tackle selenium (Se) malnutrition, biofortification is among the proposed strategies. A biosti... more To tackle selenium (Se) malnutrition, biofortification is among the proposed strategies. A biostimulant application in soils is thought to support a plant’s growth and productivity. Biofortification with Se(VI) may lead to a leaching hazard due to the high mobility of Se(VI) in the soil environment. In this study, the effect of the application of two Se(VI) rates—5 and 10 mg kg−1 soil—and a biostimulant on the Se uptake by lettuce plants and on the Se(VI) distribution in soil fractions following the plants’ harvest, was investigated. Phosphorus (P) and sulfur (S) concentrations in plants were also determined. A high Se(VI) rate suppressed plant growth, leading to a significant fresh weight decrease from 12.28 to 7.55 g and from 14.6 to 2.43 g for the control and high Se(VI) without and with biostimulants, respectively. Impaired plant growth was verified by the SPAD, NDVI and NDRE measurements. The significantly highest Se concentration in plants, 325 mg kg−1, was recorded for the hi...

Environments

Soils close to former mines or metallurgical facilities often contain extreme concentrations of p... more Soils close to former mines or metallurgical facilities often contain extreme concentrations of potentially toxic elements (PTEs), and among soil remediation actions needed, enhanced phytoextraction techniques using chelating agents could be a very promising option. In this context, a pot experiment was conducted to evaluate the effect of Na2-EDTA, olive mill wastewater (OMW), and their combination (EDTA + OMW) on As, Pb and Zn uptake by Helianthus annuus (sunflower), grown in a heavily contaminated soil from Lavrio, Greece. After harvest, aboveground and belowground biomass and the concentrations of As, Pb and Zn were determined. Additionally, composite soil samples of all treatments were subjected to appropriate sequential extraction procedures for each PTE. Results showed that although nonstatistically significant effects on plant growth and As concentration were observed, Pb and Zn plant concentrations increased by the EDTA addition, alone or combined with OMW. When the total bi...

Parlar Scientific Publications, 2017

In calcareous soils, Fe availability is highly restricted. On the other hand, Fe metabolism is in... more In calcareous soils, Fe availability is highly restricted. On the other hand, Fe metabolism is intimately related to S, N, and P ones, whilst intensive agronomic activity requires significant S inputs. How these relationships are shaped in the commonly used for lawns species Cynodon dactylon, Pennisetum clandestinum, Festuca arundinacea, Festuca rubra, Lolium perenne, Poa pratensis, Dichondra repens, and Trifolium repens, when they are grown in a medium-textured calcareous soil irrigated with slightly saline water? In this system, [Sorg] presented a wide range among the studied lawns, and two groups were distinguished: one with [Sorg] above 70 μmol g-1 DM and the other with [Sorg] below 50 μmol g-1 DM. All binary combinations of N/Sorg, P/Sorg, SO4 2-/Sorg, Fe/Sorg ratios were in very strong linear relationships, along with N/Fe vs P/Fe ratios. Sorg/Fe ratio suggested more acquisition of S relative to Fe, by the warm season grasses. The relationship between Sorg/Fe and SO4 2-/Sorg ratios suggested that Fe and SO4 2-were interconnected via the required content of Sorg and the following scenario seems to be supported: P nutrition was adjusted to N nutrition; iron was adjusted to both of them, so that N/Fe was in linear relationship to P/Fe. Sorg was adapted to both N and Fe.

Journal of Plant Nutrition, 2019

Olive is the most important fruit tree species grown in Mediterranean basin, where many times it ... more Olive is the most important fruit tree species grown in Mediterranean basin, where many times it grows under saline conditions, due to irrigation with low quality water. Olive response to salinity is cultivar dependent and the evaluation of native genotypes is an important tool in finding tolerant genetic material. For this reason, five Greek olive cultivars, i.e. "Koroneiki", "Gaidourelia", "Lefkolia Serron", "N-K Gigas" and "Throumbolia", were evaluated regarding their tolerance to sodium chloride salinity (0, 50, 100 and 200 mM). All cultivars exhibited a significant reduction of growth, while the most severe symptoms were found in "Gaidourelia" while "Lefkolia Serron" presented the least symptoms. The latter exhibited the lowest sodium concentration in the leaves and the highest in the roots. Both potassium to sodium and calcium to sodium ratios were high in "Gaidourelia" leaves and stems, suggesting that the use of nutrient concentration for comparison of olive tolerance among cultivars could lead to erroneous results. The best indicator proved to be the determination of nutrient relative concentration compared to corresponding cultivar's control, as "Gaidourelia" exhibited the highest sodium relative concentration as well as the lowest nutrient ratios, revealing its inability to restrain sodium in the root level.

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Environments

Selenium adsorption/desorption behavior was examined for eight Greek top soils with different pro... more Selenium adsorption/desorption behavior was examined for eight Greek top soils with different properties, aiming to describe the geochemistry of the elements in the selected soils in terms of bioavailability and contamination risk by leaching. Four soils were acid and four alkaline, and metal oxides content greatly differed between the two groups of soils. The concentrations of Se(IV) used for the performed adsorption batch experiments ranged from 1 to 50 mg/L, while the soil to solution ratio was 1 g/0.03 L. Acid soils adsorbed significantly higher amounts of the added Se(IV) than alkaline soils. Freundlich and Langmuir equations adequately described the adsorption of Se(IV) in the studied soils, and the parameters of both isotherms significantly correlated with soil properties. In particular, both KF and qm values significantly positively correlated with ammonium oxalate extractable Fe and with dithionite extractable Al and Mn, suggesting that amorphous Fe oxides and Al and Mn oxi...

Η διαχείριση του φωσφόρου αποτελεί μια πρόκληση με πολλαπλές όψεις από την επισιτιστική ασφάλεια ... more Η διαχείριση του φωσφόρου αποτελεί μια πρόκληση με πολλαπλές όψεις από την επισιτιστική ασφάλεια και την αειφόρο χρήση των φυσικών πόρων μέχρι την παραγωγικότητα των οικοσυστημάτων και την περιβαλλοντική υποβάθμιση. Η αειφόρος χρήση των φωσφορικών αποθεμάτων μέσω της ορθολογικής διαχείρισης των φωσφορικών λιπασμάτων αποτελεί ένα πρώτο βήμα της διασφάλισης του σημαντικού αυτού μη ανανεώσιμου φυσικού πόρου για τις επόμενες γενεές καθώς και την πιο ομοιογενή κατανομή του φωσφόρου τόσο σε περιφερειακό όσο και σε παγκόσμιο επίπεδο.

Phosphorus (P) is an important nutrient for flora and fauna, and is an essential element during e... more Phosphorus (P) is an important nutrient for flora and fauna, and is an essential element during energy transformation processes of the living world. Phosphate rock, which is the most common source of phosphorus, is globally used in various forms, in order to boost agricultural productivity and cover contemporary food demand. Its low price in combination with its abundance on several areas on our planet led to overexploitation phenomena and unsustainable phosphorus management, resulting in important environmental and socio-economic problems. Eutrophication, soil over-accumulation, nutrient depletion due to soil erosion processes, contamination of the extraction sites, reduction of global available resources, massive price fluctuations and food crisis are some of these phosphorus-related problems with a global impact. The uncertainties and the underlying risks prevailing due to improper use of phosphate resources denote that sustainable soil phosphorus management should be set amongst the top priorities in global level. The local adaptation of the 4R Nutrient Stewardship approach can be proved a very promising tool in order to develop a sound soil phosphorus management program. In Europe, despite the multi-dimensional problems caused by unsustainable phosphorus use of the previous decades, significant steps are taken to restore the problems and establish a framework focusing on natural resources and socio-economic system protection.