Search

Context. Organic amendments (OAs) from agricultural and non-agricultural industries provide an alternative source of nitrogen (N) and other nutrients for crop production, especially with increasing costs of synthetic fertilisers. Aims. This study examined the fate of urea in combination with OA in the form of raw mill mud, composted mill mud and high N compost in a maize field experiment on a sandy loam soil in a rain-fed subtropical environment. Methods. OAs (346 kg N [ha.sup.-1]) were incorporated at sowing with [sup.15]N labelled urea (200 kg N [ha.sup.-1]) applied 28 days later, including a no OA control. Key results. Grain yield, aboveground biomass and roots were not significantly different across all treatments, averaging 8.1, 17.4 and 1.3 t [ha.sup.-1] at harvest. Total N uptake was 249.1 kg N [ha.sup.-1] (on average) with fertiliser, native soil N and OAs sources accounting for 49.5, 44 and 6.5% of the total N uptake respectively. There was no significant difference in N fertiliser recovery between the OA treatments and the unamended control, with 61.7 and 3.7% of the applied N recovered in the plant and soil (to 100 cm), respectively, at harvest. Nitrogen fertiliser losses were equivalent to 33.6% of the applied N and were attributed to N leaching after extensive rainfall events late in the growing season. Conclusions. OAs with high mineral and/or organic N content at time of application can supply significant amounts of plant available N but high levels of soil mineral N at sowing may hinder their full potential. Implications. Reducing N loss and cost, and improving overall soil fertility by replacing synthetic N fertilisers with OAs may contribute to more environmentally sustainable crop production. Keywords: [sup.15]N, compost, fertiliser, leaching, maize, mill mud, nitrogen, organic wastes., Introduction The ever-increasing cost of synthetic nitrogen (N) fertiliser and the demand for more sustainable production systems have promoted the use of organic amendments (OAs) from agricultural (e.g. crop residues, [...]

Abstract: Given its high pore volume and adsorption capacity, and when applied as an agricultural soil amendment, its ability to enhance the soil's nutrient- and water- holding capacities, biochar has [...]

Purpose: We investigated the effect that ashes may have on the soil microbial activity. Our hypothesis is that different wood ashes and different proportions of them could have beneficial or detrimental effects depending on the applied dose.Materials and methods: Dehydrogenase activity and soil oxygen consumption were used to evaluate the potential improvement of soil conditions through the application of two different wood ashes coming from industrial waste. Different ash proportions and time dependence have been used to make comparisons. The respiration curves obtained through a closed-jar incubation experiment were well fitted by a sigmoidal function, the derivative of which yields the time evolution of the consumption rate.Results and discussion: The results indicate that the dehydrogenase activity and soil oxygen consumption are very sensitive to the presence of ashes in the soil, and the reached values of both are linked to the applied dose of them. In our research, soil oxygen consumption is time and rate dependent of ash application. The curves show that parameter was affected by the ashes in different way, raising the respiration rate, and stretching the biological activity period.Conclusions: Dehydrogenase activity and soil oxygen consumption are very sensitive to the presence of ashes and can be used to assess their potential use as amendments. The results of this paper can contribute to the required knowledge in order to use ashes in a sustainable way. Ashes coming from olive marc and vine shoots may affect positively the soil respiration and, therefore, the soil fertility, if they are applied in moderate amounts. [ABSTRACT FROM AUTHOR]

Abstract: The restoration of soils affected by mining activities depends on the improvement of soil physical quality. This study aimed to determine the medium‐term effects of organic amendments and mulches on soil physical properties and soil hydrological response. The experimental restoration was conducted in a homogeneous slope using a factorial design (organic amendments × mulches). The organic amendments consisted of compost from domestic organic residues, sewage sludge from an urban water treatment facility, and a control without amendment. The mulches consisted of gravel, woodchips, and a control without mulch. Modifications of the soil structure induced by the combinations of techniques were quantified by micromorphometric analysis of 2D porosity. Undisturbed soil cores were collected to determine the soil bulk density. Soil hydrological behaviour was determined by rainfall simulations. Samples from natural undisturbed soils surrounding the quarry were also taken as a reference. Restored soils with organic amendments have a higher total porosity than did nonamended substrates. Each restoration treatment combination resulted in a different pore system with very diverse hydrological responses. Organic amendments resulted in infiltration improvement and water erosion reduction. The woodchip mulch was more effective at trapping runoff and sediment, although this type of mulch did not favour vertical water movement towards deeper horizons. Therefore, the use of organic amendments should be encouraged in mine soil restoration and should be strongly recommended for its proven environmental benefits (enhancement of soil structure and infiltration and reduction of soil losses). However, the mulches did not produce the expected results in the tested arid–semiarid area. [ABSTRACT FROM AUTHOR]

Abstract: The mudflats along the east coast of China can be important alternative sources for arable lands after amendment. The newly reclaimed mudflats as typical saline soils are not suitable for cultivation owing to high salinity and nutrient deficiencies. The key to amending mudflat saline soils into fertile soils is to reduce salinity in the top layer of soil. Salinity reduction is usually accomplished through rainfall and freshwater irrigation. However, lack of good soil aggregation status might attribute to salt solution rise through soil capillary. Increasing soil organic matter promoted the formation of organo‐mineral complexes and clustered soil aggregates, which is a prerequisite of hindering re‐salinization, improving fertility and facilitating the evolution of coastal mudflat soil into agricultural soil. Research on the formation of clustered soil aggregates during the evolution of mudflat soil into fertile soil should focus on the formation mechanism, influencing factors and regulatory mechanism of organo‐mineral complexes in the early stage after organic matter enters the soil. In addition, exploration of the effects of the special properties of mudflat soil, for example, high saline, high pH and low levels of clay particles, on the formation and stability of organo‐mineral complexes in soil is necessary. Research on this topic can provide scientific evidences to efficiently utilize organic resources and accelerate the evolution of mudflat soil into agricultural soil. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study examines the potential for silicon soil amendments and nitrogen to reduce apple snail, Pomacea canaliculata Lamarck, damage to rice ( Oryza sativa L.) seedlings. A rate of 75 kg/ha of nitrogen applied as (NH 4 ) 2 SO 4 to rice (cv IR64 and cv YTH183) seedbeds increased seedling biomass, allowing the seedlings to gain critical stem thickness and avoid snail herbivory. These seedlings remained relatively large after exposure to snails in pot experiments, mainly because of faster growth rates, but also due to lower damage from snails to >21 day-old IR64 seedlings. Silicon applied as Na 2 O 3 Si·9H 2 0 alone (without nitrogen) reduced seedling growth compared to control seedlings. When nitrogen and silicon were applied together, the addition of silicon resulted in reduced seedling growth in YTH183 compared to seedlings treated with nitrogen alone. However, the same effect was not noted for IR64 seedlings, indicating clear variety-specific responses to seedbed inputs. Regardless of variety, silicon-treated seedlings that were transplanted to snail-infested pots at 21 days after seeding (DAS) had lower biomass than seedlings without silicon despite silicon-treated IR64 seedlings having less snail damage than untreated controls. From an experiment conducted in snail-infested ponds, we found no difference between snail damage to silicon (SiO 2 )-treated and control cv IR50 seedlings. Although we did not determine silicon levels in plant tissues, our results indicate that the effects of silicon soil amendments are largely insufficient to reduce the impact of apple snails to young rice seedlings (≤21 DAS). [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of different biochars on soil enzyme activities associated with soil carbon (C) mineralisation. Biochars were produced from two types of feedstock (fresh dairy manure and pine tree woodchip) at temperatures of 300°C, 500°C, and 700°C. Each biochar was mixed at a ratio of 5% (w/w) with a forest loamy soil and the mixture was incubated at 25°C for 180 days. Soil mineralisation rates, soil dissolved organic C, soil microbial biomass C, and five soil enzyme activities were measured during different incubation periods. Results showed that biochar addition increased soil enzyme activities at the early stage (mainly within the first 80 days) because biochar brought available nutrients to the soil and increased soil dissolved organic C and microbial activity. Soil enzyme activities were enhanced more by the dairy manure biochars than by the woodchip biochars (P< 0.05). The enhancement effect on enzyme activities (except catalase activity) was greater in the treatments with biochars produced at lower pyrolysis temperature (300°C). Linear relationships between some soil enzymes and C-mincralisation rates might indicate that the increased enzyme activities stimulated soil C mineralisation at the early stage. However, the biochar additions could result in great C sequestration in the long term, especially for the woodchip biochars pyrolysed at higher temperatures. Additional keywords: biochar, soil carbon mineralisation, soil carbon sequestration, soil enzyme activity., Introduction Enzymes are involved in many biochemical processes in soils, such as the organic matter decomposition, carbon (C) mineralisation, and nutrient cycling (Patra et al. 2006; Makoi and Ndakidemi 2008). [...]

Recycling of organic wastes via their incorporation in cultivated lands is known to alter soil structural stability. Aggregate stability tests are commonly used to express quantitatively the susceptibility of soil structural stability to deformation. The objective of this study was to investigate the effects of biosolids addition, namely composted manure (MC) and activated sludge (AS), and spiking of the soils with orthophosphate (OP), phytic acid (PA) or humic acid (HA), on soil aggregate stability of semi-arid loamy sand, loam and clay soils before and after subjecting the soils to six rain storms (each 30 mm rain with a break of 3-4 days). Aggregate stability was determined from water-retention curves at high matric potential. The effects of the applied amendments on pre- and post-rain aggregate stability were inconsistent and soil-dependent. For the pre-rain state, all of the tested amendments improved aggregate stability relative to the control. For the post-rain condition, aggregate stability was lower in the MC, OP and PA treatments and higher in the AS and HA treatments than in the control. The coarse-textured loam and loamy sand soils were more affected by the soil amendments than the clay soil. For the pre-rain state, addition of organic matter significantly improved macro-porosity and hence the stability of apparent macro-aggregate (>250 µm). Our results indicate a possible advantage for separation of aggregates into macro- and micro-aggregates for more precise evaluation and understanding of the effects organic amendments might have on aggregate stability. Additional keywords: aggregate stability, biosolids, high-energy moisture characteristic, humic acid, manure, slaking, sludge., Introduction Wet aggregate stability is increasingly being used to evaluate cohesion of aggregates, and the dynamics and nature of the bonding between particles (Kay and Angers 2002), all of which [...]

Any strategy towards widespread adoption of biochar as a soil amendment is constrained by the scarcity of field-scale data on crop response, soil quality and environmental footprint. Impacts of biochar as a soil amendment over a short period based on laboratory and greenhouse studies are often inconclusive and contradictory. Yet biochar is widely advocated as a promising tool to improve soil quality, enhance C sequestration, and increase agronomic yield. While substantial reviews exist on positive aspects of biochar research, almost no review to date has compiled negative aspects of it. Although biochar science is advancing, available data indicate several areas of uncertainty. This article reviews a range of negative impacts of biochar on soil quality, crop yield, and associated financial risk. This review is important because advances in biochar research demand identification of the risks (if any) of using biochar as a soil amendment before any large-scale field application is recommended. It is the first attempt to acknowledge such issues with biochar application in soil. Thus, the aims of this review arc to assess the uncertainties of using biochar as a soil amendment, and to clarify ambiguity regarding interpretation of research results. Along with several unfavourable changes in soil chemical, physical and biological properties, reduction in crop yield has been reported. Relative to controls, the yield for biochar-amendcd soil (application rate 0.2-20% w/w) has been reduced by 27, 11,36, 74, and 2% for rice (Oryza sativa L.) (control 3.0 Mg [ha.sup.-1]), wheat (Triticum spp. L.) (control 4.6 Mg [ha.sup.1]), maize (Zea mays L.) (control 4.7 Mg [ha.sup.-1]), lettuce (Lactuca sativa L.) (control 5.4 Mg [ha.sup.-1]), and tomato (Solatium lycopersicum L.) (control 265 Mg [ha.sup.-1]), respectively. Additionally, compared with unamended soils, gaseous emissions from biochar-amended soils (application rate 0.005-10% w/w) have been enhanced up to 61, 152 and 14% for C[O.sub.2] (control 9.7 Mg [ha.sup.-1] [year.sup.-1]), C[H.sub.4] (control 222 kg [ha.sup.-1] [year.sup.-1]), and [N.sub.2]O (control 4.3 kg [ha.sup.-1] [year.sup.-1]), respectively. Although biochar has the potential to mitigate several environmental problems, the data collated herein indicate that a systematic road-map for manufacturing classification of biochars, and cost-benefit analysis, must be developed before implementation of fieldscale application., Introduction Ever since the description of 'tera preta do Indio' by Wim Sombroek (Sombrock 1966) was published, biochar has been widely advocated to mitigate many environmental and agronomic problems (e.g. [...]

The use of conventional methods to clean up the soil is very expensive and destructive to the ecosystem. The concept of phytoextraction has been introduced to safely manage soils contaminated with heavy metals. However, using plants to remediate polluted soils is a lengthy process. This has necessitated the use of amendments to potentially enhance solubilization of metals in order to increase their bioavailability in the soil solution. A pot experiment was conducted to study the effect of some selected pH lowering amendments [elemental sulphur and (NH)SO] on the solubility and availability of Cd and Zn. The application of these amendments resulted in a decrease in the pH of the soil. The decrease in pH significantly enhanced the solubilization and the mobility of Cd and Zn into the soil solution. The CaCl extraction protocol was employed to study the effects of the various amendments on the mobility of Cd and Zn. [ABSTRACT FROM AUTHOR]

Aminocyclopyrachlor is a pyrimidine carboxylic acid herbicide used to control broadleaf weeds and brush. Amending soil with activated charcoal is recommended to prevent off-site transport of aminocyclopyrachlor and non-target plant damage. We used the batch-equilibrium method to determine the concentration of aminocyclopyrachlor in a pseudo-steady state with biochar, soil, and biochar-soil systems (<10% biochar by weight). We observed that aminocyclopyrachlor is mobile in soils. Soil incorporation of activated charcoal removed nearly all of the aqueous aminocyclopyrachlor thereby limiting its bioavailability to non-target flora. On the other hand, biochars were less effective than activated charcoal. Biochar produced from olive mill waste feedstock was the most effective biochar that we assessed for reducing the aqueous herbicide concentration. Although these biochars reduced the aminocyclopyrachlor concentration, they would not be practical remediation media due to the extraordinarily high application rates required to reduce the concentration by 50% (2.13 × 105 kg ha−1–7.27 × 105 kg ha−1). [Copyright &y& Elsevier]

Amending contaminated soils with organic wastes can influence trace element mobility and toxicity. Soluble concentrations of metals and arsenic were measured in pore water and aqueous soil extracts following the amendment of a heavily contaminated mine soil with compost and biochar (10% v:v) in a pot experiment. Speciation modelling and toxicity assays (Vibrio fischeri luminescence inhibition and Lolium perenne germination) were performed to discriminate mechanisms controlling metal mobility and assess toxicity risk thereafter. Biochar reduced free metal concentrations furthest but dissolved organic carbon primarily controlled metal mobility after compost amendment. Individually, both amendments induced considerable solubilisation of arsenic to pore water (>2500 μg l−1) related to pH and soluble phosphate but combining amendments most effectively reduced toxicity due to simultaneous reductions in extractable metals and increases in soluble nutrients (P). Thus the measure–monitor-model approach taken determined that combining the amendments was most effective at mitigating attendant toxicity risk. [Copyright &y& Elsevier]

Improved approaches are needed to assess bioavailability of hydrophobic organic compounds in contaminated soils. Performance of thin-film solid-phase extraction (TF-SPE) using vials coated with ethylene vinyl acetate was compared to earthworm bioassay (Lumbricus terrestris). A DDT and dieldrin contaminated soil was amended with four organic carbon materials to assess the change in bioavailability. Addition of organic carbon significantly lowered bioavailability for all compounds except for 4,4′-DDT. Equilibrium concentrations of compounds in the polymer were correlated with uptake by earthworms after 48d exposure (R 2 = 0.97; p < 0.001), indicating TF-SPE provided an accurate uptake simulation. Bioavailability of residues in soil was compared with a spiked soil aged for 90d in laboratory. Dieldrin and DDX were respectively 18% and 11% less bioavailable in contaminated soil relative to spiked soil despite >40yr of aging. Results show that TF-SPE can be useful in examining potential risks associated with contaminated soils and to test effectiveness of remediation efforts. [Copyright &y& Elsevier]

Animal manure can be an important resource providing soil available N for plant needs, but determining the nutrient availability resulting from such amendments is difficult. A study was conducted to examine changes in electromagnetic induction (EMI) soil conductivity and available N levels during four growing seasons in relation to manure or compost application and use of a green winter cover crop. With simultaneous soil samples, a series of soil conductivity maps of a research cornfield were generated using a global positioning system (GPS) and EMI methods. The Clay Center, NE, site was treated during a 10-yr period with a winter wheat (Secale cereale L.) winter cover crop (+CC) and no-cover crop (-CC). The site was split for subtreatments of manure and compost at rates matching either the P or the N requirements of silage corn (Zea mays L.). Differences between the +CC and -CC treatments for values of N[O.sub.3]-N and water-filled pore space (WFPS), as estimated by apparent electrical conductivity ([EC.sub.a]), were compared for each year. Differences in profile weighted soil conductivity explained 79.5, 98.0, 93.4, and 98.4% of the variability due to N[O.sub.3]--N differences, and only 20.5, 2.0, 6.6, and 1.6% of the variability due to WFPS differences for years 2000, 2001, 2002, and 2003, respectively. Sequential measurement of profile-weighted soil electrical conductivity ([EC.sub.a]) was effective in identifying the dynamic changes in plant-available soil N, as affected by animal manure and anhydrous ammonia fertilizer treatments during four corn growing seasons.

ABSTRACT Air-surface exchange of mercury (Hg) was measured from soil low in Hg (0.013 mg/kg) amended with four different ash materials: a wood ash containing ~10% coal ash (0.070 mg/kg [...]

Three compost types were tested for their erosion protection and runoff control properties, along with their affects on water quality. Compost types tested were a fine-textured product made from biosolids, a medium-textured product made from grain processing and paper mill sludge, and a coarse-textured product made from yard trimmings. Blanket applications of two inches performed equally to those of four inches.

Methods of odor control for biosolids application are described. These include enhanced digestion of biosolids, including temperature-phased anaerobic digestion, and improved soil incorporation techniques such as subsurface injection.

The article examines the importance of using appropriate technology for environmental remediation, focusing on the susceptibility of species such as earthworms to chemicals in soil amendments.

Research suggests that a combination of phosphorus-laden sludge and dewatered anaerobically digested primary sludge offer agricultural sites a longer productive life than the primary sludge alone, and meet established heavy metal criteria. Data were obtained from studies conducted on landscape applications of sludges produced by Saskatchewan's Regina Wastewater Treatment Plant.

The availability of Pb and As in an historically contaminated orchard soil, after amendment with compost and aging in the field, was determined by single-step chemical extraction with 1.0 M ammonium acetate at pH 4.8, sequential extraction using the modified BCR test, and a redworm bioassay in the laboratory. The efficiency of soil Pb extraction by ammonium acetate was greater at higher total soil Pb but was reduced by compost amendment. Conversely, the extraction efficiency of total soil As increased with compost amendment, but was not sensitive to total soil As. The redworm bioassay indicated Pb (but not As) bioavailability to be reduced by soil amendment with compost, a result consistent with the ammonium acetate extraction test but not reflected in modified BCR test. Electron microprobe studies of the orchard soil revealed Pb and As to be spatially associated in discrete particles along with phosphorus and iron. [Copyright &y& Elsevier]

Mining is an activity that has been practiced by humans for years. Abandoned mines, tailings and spoils may have significant impact on the neighboring environments. The derelict mines and waste generated are the major issues of concern, as they are capable of discharging acid waters that are often saturated with iron, metals and metalloids. The process of rehabilitation is vital, which should include neutralizing the acid generating potential of the spoils and support vegetation. This research focuses on creating artificial soil for mine rehabilitation process by rejuvenating the mine waste with amendments, so that they support microbial growth and thus support vegetation in abandoned mines. Evidence for the growth of microorganisms and its support to vegetation is established by quantifying the DNA and conducting growth test with grass. [ABSTRACT FROM AUTHOR]

There are reports that the application of fly ash, compost and press mud or a combination thereof, improves plant growth, soil microbial communities etc. Also, fly ash in combination with farmyard manure or other organic amendments improves soil physico-chemical characteristics, rice yield and microbial processes in paddy fields. However, the knowledge about the impact of fly ash inputs alone or in combination with other organic amendments on soil methanotrophs number in paddy soils is almost lacking. We hypothesized that fly ash application at lower doses in paddy agriculture soil could be a potential amendment to elevate the paddy yields and methanotrophs number. Here we demonstrate the impact of fly ash and press mud inputs on number of methanotrophs, antioxidants, antioxidative enzymatic activities and paddy yields at agriculture farm. The impact of amendments was significant for methanotrophs number, heavy metal concentration, antioxidant contents, antioxidant enzymatic activities and paddy yields. A negative correlation was existed between higher doses of fly ash-treatments and methanotrophs number (R 2=0.833). The content of antioxidants and enzymatic activities in leaves of higher doses fly ash-treated rice plants increased in response to stresses due to heavy metal toxicity, which was negatively correlated with rice grain yield (R 2=0.944) and paddy straw yield (R 2=0.934). A positive correlation was noted between heavy metals concentrations and different antioxidant and enzymatic activities across different fly ash treated plots.The data of this study indicate that heavy metal toxicity of fly ash may cause oxidative stress in the paddy crop and the antioxidants and related enzymes could play a defensive role against phytotoxic damages. We concluded that fly ash at lower doses with press mud seems to offer the potential amendments to improving soil methanotrophs population and paddy crop yields for the nutrient poor agriculture soils. [Copyright &y& Elsevier]

The wide distribution and high heterogeneity of different elements in biochars derived from diverse feedstocks make it difficult to regulate their application in soil and to evaluate the maximum potential contribution of the nutrients and trace metals as well as the potential risk of toxic metals. This study classified 20 biochars, covering six typical categories, into three clusters according to their similarity and distance on nutrients and minerals using cluster analysis. Four principle components (PC) were extracted using factor analysis to reduce dimension and clearly characterize the mineral profile of these biochars. The contribution of each group of elements in the PCs to every cluster was clarified. PC1 had a high loading for Mg, Cu, Zn, Al, and Fe; PC2 was related to N, K, and Mn; and PC3 and PC4 mainly represented P and Ca. Cluster 1 included bone dregs and eggshell biochars with PC3 and PC4 as the main contributors. Cluster 2 included waterweeds and waste paper biochars, which were close to shrimp hull and chlorella biochars, with the main contributions being from PC2 and PC4. Cluster 3 included biochars with PC1 as the main contributor. At a soil biochar amendment rate of 50 t ha-1, the soil nutrients were significantly elevated, whereas the rise in toxic metals was negligible compared with Class I of the China Environmental Quality Standards for Soil. Biochar can potentially supply soil nutrients and trace metals, and different cluster biochars can be applied appropriately to different soils so that excessive or deficient nutrient and metal applications can be avoided. [ABSTRACT FROM AUTHOR]

Abstract: Extensive use of biochar to mitigate N2O emission is limited by the lack of understanding on the exact mechanisms altering N2O emissions from biochar-amended soils. Biochars produced from giant reed were characterized and used to investigate their influence on N2O emission. Responses of N2O emission varied with pyrolysis temperature, and the reduction order of N2O emission by biochar (BC) was: BC200 ≈ BC600 > BC500 ≈ BC300 ≈ BC350 > BC400. The reduced emission was attributed to enhanced N immobilization and decreased denitrification in the biochar-amended soils. The remaining polycyclic aromatic hydrocarbons (PAHs) in low-temperature biochars (300–400 °C) played a major role in reducing N2O emission, but not for high-temperature biochars (500–600 °C). Removal of phenolic compounds from low-temperature (200–400 °C) biochars resulted in a surprising reduction of N2O emission, but the mechanism is still unknown. Overall, adding giant reed biochars could reduce N2O evolution from agricultural soil, thus possibly mitigating global warming. [Copyright &y& Elsevier]

Abstract: Coupling with triolein-embedded cellulose acetate membrane (TECAM) technique, hydroxypropyl β-cyclodextrins (HPCD) extraction method, and the greenhouse pot experiments, the influences of biochars on polychlorinated biphenyls (PCBs) bioavailability in soil to plant (Brassica chinensis L. and Daucus carota) were investigated. Addition of 2% biochars to soils significantly reduced the uptake of PCBs in plant, especially for di-, tri- and tetra-chlorobiphenyls. PCBs concentrations in the roots of B. chinensis and D. carota were reduced for 61.5–93.7%, and 12.7–62.4%, respectively in the presence of biochars. The kinetic study showed that in the soils amended with/without biochars, PCBs concentrations accumulated in TECAM, as well as in the HPCD extraction solution, followed significant linear relationships with those in plant roots. Application of biochars to soil is a potentially promising method to reduce PCBs bioavailability whereas TECAM technique can be a useful tool to predict the bioavailability of PCBs in soil. [Copyright &y& Elsevier]

A field investigation was carried out to determine PBDE concentrations over a one-year period in agricultural soils onto which 80 tonnes biosolids/hectare had been applied. The PBDE concentrations increased from 80 to 300 pg/g dry weight basis to 300 × 103–600 × 103 pg/g dw due to biosolids application, and PBDEs migrated downwards to depths of at least 0.85 m. Concentrations decreased non-uniformly with depth. PBDE levels decreased exponentially in the topmost biosolids-amended soils layer, while increasing in the next underlying soil layer over the one-year period. The rate of decrease of total PBDE mass in the top 0.00–0.05 m layer was almost two orders of magnitude greater than the rates of increase in total PBDE mass in the lower layers, indicating that effects such as photodegradation and/or volatilization likely were to have been significant in the surface layer. [Copyright &y& Elsevier]

Nine dissimilar biochars, produced from varying feedstock at different pyrolysis temperatures, are appraised with respect to concentrations of potentially toxic elements, specifically, metals, metalloids and polycyclic aromatic hydrocarbons (PAHs). Concentrations of the metals and metalloids varied with the following ranges (mg kg−1): 0.02–0.94, Cd; 0.12–6.48, Cr; 0.04–13.2, Cu; 0.1–1.37, Ni; 0.06–3.87, Pb; 0.94–207, Zn and 0.03–0.27, As. Σ16PAH concentrations (16 Environmental Protection Agency (EPA) PAHs) range between 0.08 mg kg−1 to 8.7 mg kg−1. Subsequent comparison with background soil concentrations, concentration applied to the regulation of composted materials (Publicly Available Specification (PAS 100)) and European Union (EU) regulations relating to the application of sewage sludge to agricultural land suggest low risk associated with the concentrations of PTEs observed in biochar. Collectively, results suggest that environmental impacts attributable to metals, metalloids and PAHs associated with biochar following its application to soil are likely to be minimal. [Copyright &y& Elsevier]

Organic amendment (OA) addition is an agricultural practice that can greatly affect pesticide behavior in soil. The influence of three OAs, consisting of a liquid amendment (LOA), solid (SOA) humic amendment, and a solid urban waste (SUW), on sorption, persistence, and leaching potential of simazine (2-chloro-4,6-bis (ethylamino)-s-triazine) and 2,4-D (2,4-dichlorophenoxyacetic acid) in a sandy soil (P2) has been investigated. The OAs were added to P2 at a rate of 5% (w/w). Sorption was studied using the batch equilibration technique, degradation by incubations at 20 [degrees] C and -0.33 kPa moisture content, and leaching using handpacked soil columns. Simazine sorption increased in the order of P2 [less than or equal to] P2 + LOA < P2 + SUW < P2 + SOA. The herbicide, 2,4-D, did not sorb on P2 soil, but in amended soils sorption increased in the same order as simazine. The lower sorption of both herbicides in P2 + LOA as compared with P2 + SOA and P2 + SUW is attributed to higher dissolved organic matter (DOM) content of LOA. Simazine's half-life was reduced upon amendment. Degradation of 2,4-D followed a sigmoidal rate in P2, P2 + SOA, and P2 + SUW, but not in P2 + LOA, in which 2,4-D persistence was much higher. The higher stability of 2,4-D in P2 + LOA has been attributed to 2,4-D-dissoved organic C interactions. Leaching studies indicate that degradation affects movement to a higher extent than sorption, specially in the case of 2,4-D in P2 + LOA soil, in which the amounts leached are much higher than those in unamended soil. In the case of simazine and P2 + SUW soil, greater reduction in large-size conducting pores upon amendment, as revealed in Hg porosimetry studies, resulted in a greater reduction of leaching than that suggested from the small differences in sorption and degradation between P2 and P2 + SUW soil.

King County, Washington's public education for recycling is examined, focusing on environmentally friendly soil amendments. The campaign includes displays with brochures with information on the effects of chemical runoff on the region's salmon population, and tips for successful backyard composting.

Application of low cost amendment for pesticide retention in soil is an important area of research in environmental sciences. The present study reports the potential of coal fly ash (Inderprastha and Badarpur), a waste from thermal power stations, for retaining soil applied metolachlor and atrazine within the application zone. Both the fly ashes were highly effective in reducing the leaching losses of metolachlor and atrazine and at 2% and 5% fly ash amendment levels the herbicides were retained in the top 15cm profile of the column. However, fly ashes varied in their capacity in reducing the downward mobility of herbicides, as the Inderprastha fly ash was more effective than the Badarpur fly ash. Although fly ash contained heavy metals like Cr, Cu or Pb, but they were not detected in the leachate. Also, concentration of other metals like Zn, Mn and Fe in leachate decreased after fly ash amendment. Results of this study have implications in reducing the leaching losses of these herbicides in agricultural soils. [Copyright &y& Elsevier]

In this study we investigated the sorption of sulfamethazine (SMZ) in two soils with different physico-chemical properties and the sulfonamide short-term influence on the microbial community structure and function. The presence of manure increased the SMZ sorption, the uppermost level being measured on soil with the lower pH and the higher manure content allowed by the Italian regulation. The sulfonamide desorption was hysteretic on both soils. SMZ addition to soil at the concentration of 53.6μg/g had a significant short-term negative impact on readily culturable bacteria, potential metabolic activity (Biolog CLPP) and soil enzyme activity. Moreover, a shift of the culturable microbial populations towards a lower bacteria/fungi ratio was observed after SMZ addition. Despite the observed SMZ effects disappeared almost completely after 7 day, structural changes of microbial communities were still present in SMZ-treated soils. The results presented are remarkable since previous studies addressing the SMZ impact on soil microbial parameters failed to highlight any significant effect of the sulfonamide on microbial abundance and diversity. [Copyright &y& Elsevier]

Metal immobilization may contribute to the environmental management strategy of dredged sediment landfill sites contaminated by metals. In a field experiment, amendment effects and efficiency were investigated, focusing on plants, springtails and bacteria colonisation, metal extractability and sediment ecotoxicity. Conversely to hydroxylapatite (HA, 3% DW), the addition of Thomas Basic Slag (TBS, 5% DW) to a 5-yr deposited sediment contaminated with Zn, Cd, Cu, Pb and As resulted in a decrease in the 0.01 M Ca(NO3)2-extractable concentrations of Cd and Zn. Shoot Cd and Zn concentration in Calamagrostis epigejos, the dominant plant species, also decreased in the presence of TBS. The addition of TBS and HA reduced sediment ecotoxicity and improved the growth of the total bacterial population. Hydroxylapatite improved plant species richness and diversity and decreased antioxidant enzymes in C. Epigejos and Urtica dïoica. Collembolan communities did not differ in abundance and diversity between the different treatments. [Copyright &y& Elsevier]

Biodegradation processes and changes in microbial community structure were investigated in black carbon (BC) amended soils in a laboratory experiment using two soils (black soil and red soil). We applied different percentages of charcoal as BC (0%, 0.5% and 1% by weight) with 100 mg kg−1 of phenanthrene. Soil samples were collected at different incubation times (0, 7, 15, 30, 60, 120 d). The amendment with BC caused a marked decrease in the dissipation (ascribed to mainly degradation and/or sequestration) of phenanthrene residues from soil. Extracted phenanthrene in black soil with 1% BC were higher, oppositely in red soil, 0.5% BC amendments were higher. There were significant changes in the PLFA pattern in phenanthrene-spiked soils with time but BC had little effect on the microbial community structure of phenanthrene-spiked soils, as indicated by principal component analysis (PCA) of the PLFA signatures. [Copyright &y& Elsevier]

The effect of cable oil concentration, nutrient amendment and bioaugmentation on cable oil component biodegradation in a pristine agricultural soil was investigated. Biodegradation potential was evaluated over 21 d by measuring cumulative CO2 respiration on a Micro-Oxymax respirometer and 14C-phenyldodecane mineralisation using a 14C-respirometric assay. Cable oil concentration had a significant effect upon oil biodegradation. Microbial respiratory activity increased with increasing cable oil concentration, whereas 14C-phenydodecane mineralisation decreased. Bioaugmentation achieved the best cable oil biodegradation performance, resulting in increases in cumulative CO2 respiration, and maximum rates and extents of 14C-phenyldodecane mineralisation. Generally, nutrient amendment also enhanced cable oil biodegradation, but not to the extent that degrader amendment did. Cable oil biodegradation was a function of (i) cable oil concentration and (ii) catabolic ability of microbial populations. Bioaugmentation may enhance cable oil biodegradation, and is dependent upon composition, cell number and application of catabolic inocula to soil. [Copyright &y& Elsevier]