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Abstract: The aim of this study was to identify the effectiveness of liming in combination with vegetation for the recovery of slightly acidic, saline soils of eutrophic wetlands affected by mine wastes, under fluctuating flooding conditions. Simulated soil profiles were constructed and four treatments were assayed under greenhouse conditions: control, only plant, only liming, and liming and plant. The plant species was the halophyte Sarcocornia fruticosa. Three horizons were differentiated: A (never under water), C1 (alternating flooding-drying conditions), and C2 (always under water). The pH, Eh, salinity, and the concentrations of dissolved organic carbon and soluble metals were measured regularly for 18 weeks. Liming favoured the growth of S. fruticosa, an increase in pH and a fall in Eh. The amendment was effective for reducing Mn, Zn, and Cd in pore water of bare soils, but not Cu and Pb. In the treatment with liming and plant, the growth of S. fruticosa counteracted the effect of the amendment, strongly increasing the concentrations of metals in pore water and distributing them along the soil profile. Hence, the combined use of liming and plants may increase the risk of metals mobilisation. [Copyright &y& Elsevier]

This article aims to compare the effects of applying three doses of sewage sludge, with or without liming, on organic matter, total and available chromium (Cr), and their concentration in plants. Unfertilized (NF) and mineral treatments were used as control. Soil organic-matter (SOM) modification depended on the interaction of liming and sewage sludge implementation. Liming, high sludge doses, and mineral treatment caused less SOM in the second year of study. However, after 3 years, SOM was increased by both mineral and sludge fertilizers compared to NF treatments as result of tree development and the reduction of organic-matter mineralization into the soil. These findings could have important implications for soil carbon storage capacity. Total Cr in soil and forage was increased by sewage sludge application compared to mineral or NF treatments. Liming increased Cr availability in the spring of 2000, where sewage sludge was applied, and reduced Fe availability. [ABSTRACT FROM AUTHOR]

Abstract: Air-drying of soil samples is known to increase the exchangeable fraction of cadmium (Cd) in soil. Liming, on the other hand, reduces bioavailability of heavy metals in soil by metal hydrolysis reactions and/or coprecipitation with carbonate. However, due attention has not been paid to desorption and mobilization of Cd from air-dried and limed soils at realistic ionic strengths. We compared Cd desorption from moist and air-dried samples of two texture-contrasting soils which had been spiked with 3 or 30mg-Cd kg−1 after liming with 25mmolkg−1 of Ca(OH)2, or without prior liming. Repeated batch extraction with water and 1–10mM CaCl2 solutions was carried out, and chemical speciation of dissolved Cd performed using Visual MINTEQ. Desorption of Cd from the exchangeable pool in the soils was not exhaustive, with smaller fractions of Cd remaining after five extractions in the coarse-textured Chiba soil having lower CEC than the fine-textured Takada soil. Air-drying enhanced Cd desorption from the both soils particularly in the first extraction, with the cumulative Cd desorption after five extractions 1.5 times, on average, as large as that from the unlimed moist soils. Liming suppressed the Cd release, resulting in cumulative desorptions 0.14–0.19 times those from the unlimed counterparts. The air-drying and liming effects on Cd desorption were reflected in the apparent Cd2+/Ca2+ exchange selectivity coefficient, which was lowest in the first extraction upon air-drying, and significantly increased upon liming. Alternatively, assuming that constant Cd2+/Ca2+ exchange selectivities obtained from the moist unlimed soils apply, exchangeable Cd pools in the air-dried and limed soils were evaluated. The exchangeable pool was found to increase, on average, by 26% and 30% upon air-drying, and decrease by 79% and 86% upon liming in the Takada and Chiba soils, respectively. These results demonstrate that the size of exchangeable Cd in contaminated soils is prone to change upon drying and liming, and that the potentially desorbable Cd is only slowly mobilized under ionic strength conditions prevailing in the field. [Copyright &y& Elsevier]

Liming materials have been extensively used to immobilize heavy metals. Bacteria, archaea, and fungi are sensitive to heavy metals and play critical roles in soil biogeochemical cycling and crop health. However, the responses of bacteria, archaea, and fungi to liming materials in agricultural soils contaminated with heavy metals are still unclear. A field experiment was conducted to assess the effect of liming on the three microbial domains and the potential influencing factors in maize-planted agricultural soil contaminated with Cd and Pb. Using a high-throughput sequencing method, we found that liming materials enhanced copiotrophic bacteria (Proteobacteria, Gemmatimonadetes, and Bacteroidetes), Bathyarchaeota, and arbuscular fungi (Glomeromycota) but suppressed some oligotrophic bacteria (Chloroflexi) and saprotrophic fungi. Notably, soil-available Cd markedly influenced the community composition of prokaryotes but not that of eukaryotes. Similar edaphic factors were correlated with the relative abundance of dominant bacterial and archaeal taxa but with opposite effects. Furthermore, co-occurrence network analysis revealed that the complexity decreased but the fungal nodes and edges increased after liming, indicating that the microbial community was not highly resilient to environmental stresses and the importance of fungi in community structure was enhanced. Overall, these findings suggest that changes in microorganisms resulting from liming facilitate soil biogeochemical cycles but suppress microbial stability, potentially affecting the sustainable use of agricultural soils contaminated with heavy metals. • Liming material was applied to an agricultural soil with Cd and Pb contamination. • Liming enhanced copiotrophic but suppressed oligotrophic microbes. • Liming affected microbial communities by different mechanisms. • Microbial network complexity decreased but the importance of fungi increased. [ABSTRACT FROM AUTHOR]

Denuded landscapes adjacent to big polluters represent an extremely harsh environment for plants due to a unique combination of soil toxicity and physical stress. In a 5-year experiment we tested whether survival and performance of seedlings of Mountain birch ( Betula pubescens ssp. czerepanovii) planted in two barren sites around the nickel–copper smelter at Monchegorsk, northwestern Russia, can be enhanced by physical sheltering and how large the supposed benefits to survival and performance are in relation to liming. Seedling performance was assessed by measuring growth parameters and chlorophyll fluorescence. Physical sheltering was found to be beneficial in some conditions: when soil characteristics were not so harsh as to cause 100% mortality, sheltering increased both survival and performance of birch seedlings. Although the benefits of liming on seedling performance and survival were stronger than the benefits of sheltering, sheltering may still have its uses in restoration when large-scale liming is not applicable, for example, when the ecological side effects of liming are to be avoided. [ABSTRACT FROM AUTHOR]

In a trial to test the bioavailability of certain heavy metals from slags, twelve liming materials (including different slags) were applied at three different rates to an Acrisol (sandy loam, pH[SUB(water)] of 5.2 and CEC of 4 cmol[SUBc] kg[SUP-l]) from the South African Eastern Highveld. Two Ca(OH)[SUB2] incubations were done on the specific soil -- one in a soil to solution ratio of 1:1 before the trial and another in a soil to solution ratio of 1:2.5 on the control treatment soil after the trial. The Calcium Carbonate Equivalents in HCl (CCE) and RH-values (Resin Suspension Method) were determined for each lime before the trial. After an incubation period of three months, the pH[SUB(water)] and pH[SUB(KCl)] of each of the four replicates for every treatment was measured. An incubation curve and regression equation was drawn up for each lime using the average pH values. Lime recommendations for each lime to target pH-values of 5.8, 6.8, and 7.8 were modeled using the CCE and RH-values as well as the values from the two Ca(OH)[SUB2] incubations. The soil to solution ratio of 1:2.5 and the RH-value gave a very accurate indication of the lime required for the specified pH targets of 5.8 and 6.8. All the methods underestimated the lime required for the target of 7.8. The CCE value overestimated lime reactivity, especially in the case of courser liming materials. However, the RH-value gave a more accurate indication of the reactivity of the lime, especially through the pH ranges 5.8 to 6.8. [ABSTRACT FROM AUTHOR]