Julianna Csillag

Extraction of Soil Solution for Environmental Analysis

Abstract A centrifugation technique was applied to extract the soil solution regarded to be available for plants and to estimate in it the most mobile part of the soils metal content. Three soils having different pH, texture and water-retention characteristics were contaminated with multicomponent solutions of Cd, Cr, Ni, Pb and Zn nitrates and one of them was contaminated+acidified to different extents. The impact of the presence of sewage sludge on element concentrations in the soil solution was also assessed. The release of metals into the liquid phase was high only at excessive metal contamination and extreme acid pollution.

Comparative Effects of Rock Phosphates on Arbuscular Mycorrhizal Colonization of Trifolium pratense L.

Abstract The effect of five rock phosphates with different solubility (from Algeria, North Florida, North Carolina, Senegal, and Morocco) and that of single superphosphate (SSP) alone or with lime was investigated on the root colonization of red clover with indigenous arbuscular mycorrhizal fungi (AMF). In a pot experiment, the phosphorus (P) sources were applied at four rates (0, 100, 400, and 1600 mg total P2O5 kg−1 dry soil) to an acidic sandy soil (Nyírlugos) and to an acidic clay loam soil (Ragály). The arbuscule content of the roots was more sensitive to various rock phosphates than the infection frequency. No mycorrhizal colonization of roots was observed in the Nyírlugos soil at the 1600 mg P2O5 kg−1 level of SSP or in either soil at the 1600 mg P2O5 kg−1 level of SSP+lime, indicating that the mycorrhizal dependency of the host was eliminated by the highest soluble P concentrations in the soil.

Impact of picolinic acid on the chromium accumulation in fodder radish and komatsuna.

Effects of picolinic acid (2-pyridinecarboxylic acid) and chromium(III) picolinate was studied on the chromium (Cr) accumulation of fodder radish (Raphanus sativus L. convar. oleiformis Pers., cv. Leveles olajretek) and komatsuna (Brassica campestris L. subsp. napus f. et Thoms. var. komatsuna Makino, cv. Kuromaru ) grown in a pot experiment. Control cultures, grown in an uncontaminated soil (UCS; humous sand with pHKCl 7.48, sand texture with 12.4% clay+silt content, organic carbon 0.56%, CaCO3 2.2%, CEC 6.2 cmolc kg−1, Cr 10.6 mg kg−1), accumulated low amounts of chromium (less than 5.4 μg g−1) in their roots or shoots. When this UCS was artificially contaminated with 100 mg kg−1 Cr (CrCl3) later picolinic acid treatment promoted the translocation of chromium into the shoots of both species. In fodder radish shoots Cr concentration reached 30.4 μg g−1 and in komatsuna shoots 44.5 μg g−1. Application of ethylene diamine tetra-acetic acid (EDTA) to this Cr contaminated soil had similar effect to picolinic acid. When the UCS was amended with leather factory sewage sediment (which resulted in 853 mg kg−1 Cr in soil), Cr mobilization was observed only after repeated soil picolinic acid applications. From a galvanic mud contaminated soil (brown forest soil with pHKCl 6.77, loamy sand texture with 26.6% clay+silt content, organic carbon 1.23%, CaCO3 0.7%, CEC 24.5 cmolc kg−1, Cd 5.0 mg kg−1, Cr 135 mg kg−1, and Zn 360 mg kg−1) the rate of Cr mobilization was negligible, only a slight increase was observed in Cr concentration of fodder radish shoots after repeated picolinic acid treatments of soil. Presumably picolinic acid forms a water soluble complex (chromium(III) picolinate) with Cr in the soil, which promotes translocation of this element (and also Cu) into the shoots of plants. The rate of complex formation may be related to the binding forms and/or concentration of Cr in soil and also to soil characteristics (i.e. pH, CEC), since the rate of Cr translocation was the following: artificially contaminated soil > leather factory sewage sediment amended soil > galvanic mud contaminated soil. Four times repeated 10 mg kg−1 chromium(III) picolinate application to UCS multiplied the transport of chromium to shoots, as compared to single 10 mg kg−1 CrCl3 treatment. This also suggests that chromium(III) picolinate is forming in the picolinic acid treated Cr-contaminated soils, and plants more readily accumulates and translocates organically bound Cr than ionic Cr. Picolinic acid promotes Cr translocation in soil-plant system. This could be useful in phytoextraction (phytoremediation) of Cr contaminated soils or in the production of Cr enriched foodstuffs.

Effect of Five Phosphate Rocks on Red Clover (Trifolium pratense L.) Yield in Pot Trial

Abstract Phosphorus (P) availability in five phosphate rocks with different P solubility was compared with that in single superphosphate and superphosphate+lime in a pot experiment with red clover as test plant on a Lamellic Arenosol with sand soil texture and on a Haplic Luvisol with clay loam soil texture, both strongly acid with low P supply. Phosphorus rates in the pot experiment were 0, 100, 400, and 1600 mg total P2O5 kg−1. On both soils, there was a weak correlation between total added P and red clover P responses. If P solubility of the PRs was also taken into account, the correlation between formic acid–, citric acid–, or neutral ammonium citrate–soluble P amounts added and red clover responses became much stronger. Soil P availability was estimated by water, Olsen, Lakanen‐Erviö, and ammonium lactate tests. Among the P extractants studied, Olsen soil P test gave the best correlation with red clover yields.

Extraction and Analysis of Soil Solution of Phosphate Rock and Acid Treated Soil

Abstract Increasing basic phosphate rock (PR) rates and acid loads were applied to an acidic sandy soil in a laboratory experiment. ‘Total’ amounts of potentially toxic elements in the soil and PR samples were determined by inductively coupled plasma (ICP) spectrometry after acidic, microwave digestion. Soil solution was extracted from wet soil by centrifugation with a speed corresponding to the suction power exerted by plants at the conventional wilting point. Addition of PR generally decreased rather than increased metal concentrations in the soil solution because of its pH elevating, immobilizing effect. Except for Pb, the extreme acid treatment compensated for the immobilizing effect of PR. Release of Cd (expressed as soil solution concentration in percentage of the total amount in soil+PR) was generally highest among elements at every treatment, and Cr was the least mobile metal. The one‐time, high rate of PR application did not make a direct environmental risk probable.

Barley root growth and phosphorus bioavailability in soil treated with phosphate rocks.

The effects of five phosphate rocks (originating from Algeria, northern Florida, North Carolina, Senegal, and Morocco) with various phosphorus (P) solubilities on P bioavailability, root growth, and P uptake of spring barley crops were studied on an acidic sandy soil in microlysimeters, in a pot experiment and by dynamic simulation. Root length and P influx varied significantly, influenced by the P and calcium carbonate (CaCO3) content and reactivity of the P sources. Phosphate rock (PR) treatments enhanced root growth. The simulation results demonstrated the contribution of root hair formation and P mobilization by rhizosphere acidification in the increased acquisition efficiency of barley in PR‐treated soil.

Effect of Phosphate Rocks on Spring Barley Shoot Yield and Phosphorus Uptake in a Pot Trial

The effect of five rock phosphates (from Algeria, Florida, North Carolina, Senegal, and Morocco) and hyperphosphate on the shoot yield, phosphorus (P) concentration, and P uptake of spring barley was studied in a pot experiment on acidic sandy soil (Nyírlugos) and acidic clay loam soil (Ragály), with superphosphate as the standard P source. The effect of adding calcium carbonate (CaCO3) in combination with superphosphate (SSP) was also investigated. Averaged over the whole experiment, the shoot yield of barley was almost twice as high (3.69 g pot−1) on the clay loam soil from Ragály, which was rich in colloids, than on the colloid‐poor sandy soil from Nyírlugos (1.90 g pot−1). The P uptake, however, was only 25% higher (13.0 mg P pot−1) on the clay loam soil, averaged over the whole experiment, than on the sandy soil (10.4 mg P pot−1). This could be attributed to the fact that the P concentration of barley at tillering was almost 0.1% higher on average in the rock phosphate treatments and 0.2–0.3% higher in the SSP and SSP + CaCO3 treatments on the acidic sandy soil. On both soils, diverse P effects were observed in response to rates of 0–100–400–1600 mg total phosphorus pentoxide (P2O5) kg−1 of the different rock phosphates, adjusted on the active agent equivalence principle. The differences between the P effects, in terms of both biomass surplus and P uptake, exhibited a close correlation with the differences in the P solubility of the rock phosphates. On both soils the greatest biomass surplus and P uptake were recorded for the Algerian rock phosphate, which had excellent natural solubility. Hyperphosphate and the rock phosphates from Morocco and North Carolina were also efficient, whereas the other extreme was represented by the rock phosphates from Senegal and Florida, which had low specific surfaces, P solubility, and lime content. The differences between the rock phosphates could also be expressed in terms of relative agronomic efficiency (RAE %), when the effect of the rock phosphate was compared to that of water‐soluble P fertilizer, in the case of SSP. Averaged over the two soils and over the RAE% calculated on the basis of shoot yield or P uptake, the order obtained for the relative agronomic efficiency of the rock phosphates was the same as that observed for the solubility of the rock phosphates in neutral ammonium citrate. On both soils, the loosest correlation between rock phosphate solubility and either the shoot yield of spring barley at tillering or the P uptake was obtained when the P rates were calculated on the basis of total P content, and the closest correlation was obtained when they were calculated on the basis of the P fraction soluble in neutral ammonium citrate. This, together with the ranking of the rock phosphates on the basis of relative agronomic efficiency, suggests that under conditions similar to those of the present experiment, neutral ammonium citrate is the best solvent for determining the relative P solubility of the rock phosphates. When the effects of the various rock phosphates on the P uptake of spring barley were investigated, a close correlation was detected on both soils between differences in P effects and differences in various properties of the rock phosphates (P solubility, specific surface, CaCO3 content).