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Nowadays, for soil stabilisation and cleaner production of geo-composites, the possibility of utilizing waste rubber is in vogue. The present paper deals with experimentally investigating the mechanical and micro-structural characteristics of weak Indian clayey soil partially substituted with lime (0–3.5%) and waste rubber tyre powder (0–15%). It was observed that, with increasing lime and rubber powder content, the plasticity index of the soil decreases. The shear strength and compaction testing results reveal that adding lime and rubber tyre powder (RTP) enhances the geotechnical performance of clayey soil up to an optimum dosage value. Also, the tri-axial shear testing was performed to obtain stress-strain curves for all considered soil mixes. For modified clayey soil containing 3% lime and 12.5% rubber powder, the cohesion values and bearing capacities improved phenomenally by 36.1% and 88.6% respectively, when compared to clayey soil. Further for this mix, SEM analysis reveals a compacted microstructure which improves dry-density and California's bearing ratio among all modified mixes. The novel co-relations upon regression analysis are found able to predict plasticity index, dry density, bearing capacity and shear strength with higher confidence levels. Overall, the cost-benefit analysis worked out to obtain the optimum cost of construction of footings and flexible pavement shows cost deductions up to 19% and 39% respectively while utilizing modified clay soil mixes containing 3% lime and 12.5% rubber powder in subgrade, ultimately making production stronger, cheaper and environment friendly. • Experimental investigations on finding synergistic performance of clayey soil, lime and waste rubber tyre powder. • Atterberg's limits, shear, compaction, CBR, & microstructural characteristics shows better performance of modified mixes. • Optimised clay-lime-RTP mix reports 44% and 88.63% improvements in shear strength and bearing capacities respectively. • Decrement in productional cost of up to 39% for modified geo-mixes in road pavement and foundation constructions. [ABSTRACT FROM AUTHOR]

Current policy instruments under the EU Water Framework Directive (WFD) to mitigate phosphorus (P) loss require that P use on farms is managed through regulation of farm gate P balances. Regulation at farm scale does not account for spatial variability in nutrient use and soil fertility at field scale, affecting the costs and effectiveness of farm gate measures. This study simulated the implementation of a P loss mitigation measure coupled with improving soil fertility so that farm productivity would not be compromised. The measure was simulated at field scale and the costs and effectiveness assessed at farm scale. Effectiveness was expressed as the time taken for excessive soil P levels to decline to levels that matched off-takes and this varied temporally and spatially within and between farms ranging from 1 to 8 years. Sub-optimum soil fertility was corrected on all fields across both farms, with applications of other soil nutrients and lime to protect productivity. An increase in costs ranging from 1.5 to 116% was predicted in the first two years of the measure on both farms after-which savings of 15–31% were predicted for each subsequent year until the measure was effective in year 9. Despite initial cost increase, there was no statistically significant difference in costs over the time taken for the measure to be effective, when compared to baseline costs. Successful implementation of measures should consider the impact on farm costs and time taken for measures to environmentally effective. Adoption of measures could improve if demonstrating to farmers that costs will not vary significantly from current practice and in time may results in savings if measures are paired with correcting soil fertility and increasing yields. This 'win-win' approach could be used into the future to ensure successful implementation and uptake of measures within the farming community. • Soil P decline as a source control varied from 1 to 9 years on two farms. • Coupling P mitigation with improving fertility to protect yields is cost effective. • Effectiveness varied spatially and costs temporally in farm scale simulation. • Cost effectiveness of policy measures should be assessed over longer time periods. [ABSTRACT FROM AUTHOR]

Juglans regia, Robinia pseudoacacia, Eucalyptus sp. and Populus sp. plantations, suffering from Mn and Cu toxicity, were limed in order to reduce Cu and Mn solubility in soil. The purposes of the present work were: i) to study the changes in soil chemical properties after the addition of CaCO 3 , ii) to investigate the influence of liming on the reduction of Mn and Cu toxicity. After the addition of CaCO 3 (three applications, during three successive years), pH and CaCO 3 content were significantly increased, while organic C and N were significantly reduced. Exchangeable Ca concentrations have been slightly, or significantly, increased, while those of Mg have been decreased; in addition, ratios Ca/Mg and C/N have been significantly increased after liming. Impressive reductions of DTPA extractable Cu and Mn concentrations (more than 10 times in most cases) were recorded. It was also found that trees without Mn and Cu toxicity symptoms (healthy tress) before liming did not have, in many cases, significantly greater leaf Mn, Cu and Fe concentrations, than trees after soil liming (all the trees were healthy). This probably happened because excess Mn and Cu quantities had been accumulated into their root system. Finally, leaf Mn, Cu and Zn concentrations of trees suffering from toxicity were significantly decreased after soil liming, while leaf Fe concentrations, in all the plant species studied, were increased. [ABSTRACT FROM AUTHOR]

Agroforestry systems have been recognized as a potential greenhouse gas mitigation strategy under the Kyoto Protocol because of their ability to absorb carbon dioxide from the atmosphere and store carbon mainly in the soil. Soil particle size and land management practices are known to have a considerable influence on carbon storage in soils. This study evaluated changes in soil chemical and physical properties, and quantified and compared the amount of C stored in the bulk soil and in three different soil fractions (250–2000, 53–250 and <53 μm) at each of four soil depths (0–25, 25–50, 50–75 and 75–100 cm) in a silvopastoral system located on an acidic forest soil under Pinus radiata D. Don. Areas of this system were subjected ten years ago to one of nine fertilization treatments: three different doses of sewage sludge or no fertilization, all with or without the addition of lime, and mineral fertilizer with no liming. Seventeen years after reforestation and seven years after canopy closure, strong gradients with soil depth were found regarding soil bulk density, pH and carbon storage. Intense soil management (high doses of sewage sludge and liming) generally reduced soil carbon storage, mainly in coarse aggregates, but this could be compensated by the increase in tree and pasture development observed in soils subject to intermediate sewage sludge doses. [ABSTRACT FROM AUTHOR]

Wetlands are highly effective systems in removing large amounts of N from waters, preventing eutrophication processes. However, when wetlands are polluted by metal-mine wastes their capacity to act as green filters may be diminished. The objective of this study was to evaluate the effect of liming and plants (Sarcocornia fruticosa and Phragmites australis) on the removal of NO3 − from eutrophic water in slightly acidic, wetland soils polluted by metal-mine wastes. Simulated soil profiles were constructed and six treatments were assayed: (1) no liming + no plant, (2) no liming + S. fruticosa, (3) no liming + P. australis, (4) liming + no plant, (5) liming + S. fruticosa and (6) liming + P. australis. Three horizons were differentiated: A (never under water), C1 (alternating flooding-drying conditions) and C2 (always under water). The eutrophic water used to flood the soil profiles was enriched in N and organic carbon (pH ∼ 7.5, electrical conductivity ∼ 11 dS m−1, NO3 − ∼ 234 mg L−1 and dissolved organic carbon ∼ 106 mg L−1). The pH, Eh and concentrations of dissolved organic carbon (DOC), N–NO3 − and N–NH4 + were measured regularly for 18 weeks. Liming stimulated the growth of plants, especially for S. fruticosa (20-fold more plant biomass than without liming), increased the soil pH and favoured the decline of the Eh values, enhancing the removal of NO3 − via denitrification. Of all the treatments assayed, liming + S. fruticosa was the only treatment that removed almost completely the high concentration of NO3 − from the eutrophic flooding water, reaching ∼1 mg L−1 N–NO3 − at the end of the experiment, at all depths. The higher content of DOC in the pore water of this treatment could explain this behaviour, since more labile carbon was available to the soil microorganisms in the rhizosphere, favouring NO3 − removal through denitrification processes. However, the treatment liming + P. australis (2-fold more plant biomass that without liming) did not remove completely the high concentrations of NO3 − from the eutrophic water, except in the C2 horizon – which was permanently under water. Hence, our results show that the effectiveness of liming, regarding the removal of NO3 − from eutrophic flooding water in wetland soils polluted by metal-mine wastes, depends on the presence of plants, their growth and the production of organic compounds in the rhizospheric environment. [Copyright &y& Elsevier]

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]

The application of lime or liming materials to acid-soil grasslands might help mitigate soil acidity, a major constraint to forage productivity in many temperate mountainous grasslands. Nowadays, in these mountainous grasslands, it is essential to promote agricultural practices to increase forage yield and nutritive value while preserving biodiversity and agroecosystem functioning. Two different field experiments were conducted in the Gorbeia Natural Park, northern Spain: (i) one in a calcareous mountainous grassland (Arraba) and (ii) the other in a siliceous mountainous grassland (Kurtzegan) to study the effects of a single application of two liming products, i.e. 2429kg lime (164.3% CaCO3) ha−1 and 4734kg calcareous sand (84.3% CaCO3) ha−1, applied one month before the beginning of the sheep grazing season (May–October), on soil chemical (pH, organic C, total N, C/N ratio, %Al saturation, Olsen P, exchangeable K+ and Ca2+) and biological parameters (dehydrogenase, β-glucosidase, urease, acid phosphatase and arylsulphatase activity) as well as on botanical diversity (graminoids, forbs, shrubs) and forage yield and nutritive value (crude protein, modified acid detergent fibre, digestibility). Untreated control plots were also included in the experiment. Soil sampling was carried out at the end of the sheep grazing season (6 months after liming treatment), while botanical composition was determined one year after treatments application. Although no increase in soil pH was observed in Arraba, liming significantly increased dehydrogenase activity (an indicator of soil microbial activity) by 30.4 and 86.7% at Arraba and Kurtzegan site, respectively. Liming treatments significantly improved forage yield and nutritive value in Arraba but not in Kurtzegan. Furthermore, no differences in soil biological quality, evaluated using the “treated-soil quality index” as proposed in this work, were observed between treated and untreated soils, and between the two different lime treatments (lime, calcareous sand). It was concluded that, in acid-soil temperate mountainous grasslands, moderate liming treatments have no negative short-term effects either on soil quality or botanical composition, while resulting in improvements in forage yield and nutritive value under some conditions. [Copyright &y& Elsevier]

A need exists to improve the utilization of manure nutrients by minimizing NH3 emissions from land application of manure. Management strategies to reduce NH3 emissions are available; however, few have been validated under Canadian conditions. A well tested and accurate simulation model, however, can help overcome this challenge by determining appropriate management strategies for a given set of field conditions. The Volt'Air simulation model was utilized to estimate NH3 volatilization from manure spreading for various manure spreading considerations under a range of atmospheric conditions typically encountered in eastern Canada. Considerations included: (i) soil liming, (ii) time of day of manure spreading, (iii) rainfall (timing and amount) and (iv) manure incorporation (timing, depth and manure coverage). Results demonstrated that liming to increase soil pH, increased NH3 emissions by 3.3kg ha¿1 for each increment of 0.1 pH (up to a 1.5 total increase), over no liming at 34.6kg ha¿1. For each hour delay in manure spreading past 0800h, NH3 losses were reduced by 1.5kg ha¿1. Rainfall (10mm) at least 20h after manure application reduced losses, with increased reductions at higher rainfall amounts. Incorporation soon (1h) after application was best for NH3 mitigation. Increasing the depth of incorporation by 5cm reduced NH3 emissions by 4.4kg ha¿1; also increasing manure coverage by incorporation reduced losses by 2kg ha¿1 for each 10% increase in coverage, compared to surface application at 34.6kg ha¿1. This investigation using Volt'Air yielded valuable information about simulating manure management strategies and the magnitude of their effects on NH3 emissions. [Copyright &y& Elsevier]

The closing down of a lindane factory near Rio de Janeiro, over 45 years ago, left an area heavily contaminated with hexachlorocyclohexane (HCH). Remediation by soil liming was applied by government authorities in 1995. This study aims to evaluate the HCH distribution and impact on soil microbiota due to contamination and liming. Microcosm experiments with uncontaminated soil mixed with HCH and lime indicated that lime-promoted dechlorination of HCH molecules led to leaching and volatilization of metabolites. The treatment applied transformed but did not solve the problem as most of the HCH remains in the soil. Reduced microbial respiratory activity was measured in contaminated field samples. Higher respiration rates in uncontaminated soil were reduced by HCH and lime addition; the sole addition of HCH caused a temporary increase in soil respiration, and stimulation occurred with oxygen and/or nutrient addition. A heterotrophic bacterial population around 109 CFU/g was found in polluted field soil, some well-known degraders having been isolated. Native soil microbiota showed resistance to high amounts of HCH and alkaline pH. The results allow considering bioremediation rather than chemical treatments to clean up the area. [Copyright &y& Elsevier]

Discusses the influence of liming on soil acidification and other processes. Process of acid generation in soils; Effect of soil acidity on nutrient and heavy metal transformation in soils; Amelioration of soil acidity through liming; Interactions among lime, nutrient and heavy metal in soil.