The degradation of three- and four-ring polycyclic aromatic hydrocarbons (PAHs) in Kirk medium by Anthracophyllum discolor, a white-rot fungus isolated from the forest of southern Chile, was evaluated. In addition, the removal efficiency of three-, four- and five-ring PAHs in contaminated soil bioaugmented with A. discolor in the absence and presence of indigenous soil microorganisms was investigated. Production of lignin-degrading enzymes and PAH mineralization in the soil were also determined. A. discolor was able to degrade PAHs in Kirk medium with the highest removal occurring in a PAH mixture, suggesting synergistic effects between PAHs or possible cometabolism. A high removal capability for phenanthrene (62%), anthracene (73%), fluoranthene (54%), pyrene (60%) and benzo(a)pyrene (75%) was observed in autoclaved soil inoculated with A. discolor in the absence of indigenous microorganisms, associated with the production of manganese peroxidase (MnP). The metabolites found in the PAH degradation were anthraquinone, phthalic acid, 4-hydroxy-9-fluorenone, 9-fluorenone and 4,5-dihydropyrene. A. discolor was able to mineralize 9% of the phenanthrene. In non-autoclaved soil, the inoculation with A. discolor did not improve the removal efficiency of PAHs. Suitable conditions must be found to promote a successful fungal bioaugmentation in non-autoclaved soils. © 2010 Elsevier B.V.

Manganese peroxidase (MnP) produced by Anthracophyllum discolor, a Chilean white rot fungus, was immobilized on nanoclay obtained from volcanic soil and its ability to degrade polycyclic aromatic hydrocarbons (PAHs) compared with the free enzyme was evaluated. At the same time, nanoclay characterization was performed.Nanoclay characterization by transmission electronic microscopy showed a particle average size smaller than 100nm. The isoelectric points (IEP) of nanoclay and MnP from A. discolor were 7.0 and 3.7, respectively, as determined by micro electrophoresis migration and preparative isoelectric focusing. Results indicated that 75% of the enzyme was immobilized on the nanoclay through physical adsorption. As compared to the free enzyme, immobilized MnP from A. discolor achieved an improved stability to temperature and pH. The activation energy (Ea) value for immobilized MnP (51.9kJmol -1) was higher than that of the free MnP (34.4kJmol -1).The immobilized enzyme was able to degrade pyrene (>86%), anthracene (>65%), alone or in mixture, and to a less extent fluoranthene (<15.2%) and phenanthrene (<8.6%). Compared to free MnP from A. discolor, the enzyme immobilized on nanoclay enhanced the enzymatic transformation of anthracene in soil.Overall results indicate that nanoclay, a carrier of natural origin, is a suitable support material for MnP immobilization. In addition, immobilized MnP shows an increased stability to high temperature, pH and time storage, as well as an enhanced PAHs degradation efficiency in soil. All these characteristics may suggest the possible use of nanoclay-immobilized MnP from A. discolor as a valuable option for in situ bioremediation purposes. © 2010 Elsevier Ltd.

In this study, different growth conditions of Anthracophyllum discolor Sp4 including the effect of agitation, additions of lignocellulosic support, inducer and surfactant were evaluated on the MnP production in Kirk medium using a culture system made up of the tubes containing the glass bead. The highest MnP production (1,354 U/L on day 13) was obtained when the medium was supplemented with wheat grain and 0.25 mM MnSO 4 as inducer, under static conditions at 30°C. Two isoenzymes were purified (35 and 38 kDa respectively). MnP presented a maximal activity in the pH range between 4.5 and 5.5, a relatively high temperature tolerance (50°C) and a high catalytic activity for 2,6-dimethoxyphenol and hydrogen peroxide.

Ammonium nitrate and calcium ammonium nitrate are the most commonly used straight nitrogen fertilisers in Europe, accounting for 43% of the total nitrogen used for fertilisers. They are both produced in a similar way; carbonate can be added as a last step to produce calcium ammonium nitrate. The environmental impact, fossil energy input and land use from using gasified biomass (cereal straw and short rotation willow (Salix) coppice) as feedstock in ammonium nitrate production were studied in a cradle-to-gate evaluation using life cycle assessment methodology. The global warming potential in the biomass systems was only 22-30% of the impact from conventional production using natural gas. The eutrophication potential was higher for the biomass systems due to nutrient leaching during cultivation, while the acidification was about the same in all systems. The primary fossil energy use was calculated to be 1.45 and 1.37 MJ/kg nitrogen for Salix and straw, respectively, compared to 35.14 MJ for natural gas. The biomass production was assumed to be self-supporting with nutrients by returning part of the ammonium nitrate produced together with the ash from the gasification. For the production of nitrogen from Salix, it was calculated that 3914 kg of nitrogen can be produced every year from 1 ha, after that 1.6% of the produced nitrogen has been returned to the Salix production. From wheat straw, 1615 kg of nitrogen can be produced annually from 1 ha, after that 0.6% of the nitrogen has been returned. © 2008 Elsevier Ltd. All rights reserved.

The effects of making a 1000 ha organic farm self-sufficient in renewable fuel were studied. Biomass grown on-farm can be transported to large fuel production facilities and the fuel transported back to the farm. Two fuels, Fischer-Tropsch diesel (FTD) and dimethyl ether (DME), produced from either straw or short-rotation willow coppice (Salix), were studied. The environmental impact, land use and energy balance were calculated using life-cycle methodology. It was calculated that the straw-based systems had only 32-39% of the impact on global warming (kg [CO2-eq]) compared to the Salix-based systems. For acidification and eutrophication, the differences between the systems were less significant. The energy balances were 8.9 and 9.6 for FTD and 10.1 and 10.0 for DME, from straw and Salix, respectively. To become self-sufficient in FTD, 108 ha has to be set aside for Salix production or 261 ha of straw collected from the existing crop rotation. For DME the corresponding figures are 38 and 70 ha. The many by-products in the FTD scenarios explain the large difference between fuels. Comparing FTD and DME, the differences in environmental impact were small. Considering this, FTD is a more likely alternative since DME requires a pressurised infrastructure system and engine modifications. © 2007 IAgrE.

This study analysed a future hypothetical organic farm self-sufficient in renewable tractor fuel. Biomass from the farm was assumed to be transported to a central fuel production plant and the fuel returned to the farm, where it was utilised in fuel cell powered tractors. The land use, energy balance and environmental impact of five different scenarios were studied. In the first two scenarios, straw was used as raw material for production of hydrogen or methanol via thermochemical gasification. In the third and fourth scenarios, short rotation forest (Salix) was used as raw material for the same fuels. In the fifth scenario, ley was used as raw material for hydrogen fuel via biogas production. The straw scenarios had the lowest impact in all studied environmental impact categories since the Salix scenarios had higher soil emissions and the ley scenario had comparatively large emissions from the fuel production. The energy balance was also favourable for straw, 16.3 and 19.5 for hydrogen and methanol respectively, compared to Salix 14.2 and 15.6. For ley to hydrogen the energy balance was only 6.1 due to low efficiency in the fuel production. In the Salix scenarios, 1.6% and 2.0% of the land was set aside for raw material production in the hydrogen and methanol scenarios respectively. In the straw scenarios no land needed to be reserved, but straw was collected on 4.3% and 5.3% of the area for hydrogen and methanol respectively. To produce hydrogen from ley, 4% of the land was harvested. The study showed that the difference in environmental performance lay in choice of raw material rather than choice of fuel. Hydrogen is a gas with low volumetric energy density, which requires an adapted infrastructure and tractors equipped with gas tanks. This leads to the conclusion that methanol probably will be the preferred choice if a fuel cell powered farm would be put into practice in the future. © 2009 Elsevier Ltd. All rights reserved.

Innehåll av kadmium och fosfor varierar mellan biogödsel från olika samrötningsanläggningar. De substrat som används för biogas- och biogödselproduktion har generellt ett visst innehåll av kadmium. Vidare konstateras att innehållet av kadmium varierar mycket mellan olika substrat. Det är några av slutsatserna från studien som gjorts av SP Sveriges Tekniska Forskningsinstitut och JTI – Institutet för Jordbruks- och Miljöteknik på uppdrag av Avfall Sverige.

Vilka substrat som används för produktion av biogödsel och biogas är avgörande för biogödselns kvalitet. En av de viktigaste parametrarna är biogödselns innehåll av kadmium. Eftersom kadmium är en giftig tungmetall vars förekomst och spridning ska minska, ett så kallat utfasningsämne, är minimering av dess förekomst i biogödsel av högsta vikt. En annan avgörande kvalitetsaspekt är biogödselns nytta, det vill säga innehållet av näringsämnen. Innehållet av fosfor är särskilt intressant eftersom det är en ändlig resurs.

Grundat på dessa förutsättningar ligger fokus i detta projekt främst på innehållet av kadmium och fosfor i biogödsel samt i de substrat och råvaror som används för biogas- och biogödselproduktion. Eftersom kadmium frigörs vid brytning av fosfor har kvoten för innehållet av dessa två ämnen traditionellt använts för beskrivning av handelsgödselns kvalitet. Därför används kadmiumfosforkvoten även i detta projekt.

Projektets syfte har varit att ta fram underlag och verktyg för att värdera substrat med avseende på deras innehåll av kadmium. Ett beräkningsverktyg för beräkningar av kadmiuminnehåll i substrat och biogödsel har tagits fram. Med hjälp av verktyget beräknas kadmiumfosforkvoten i biogödseln utifrån användarens inmatade värden för ingående substrat alternativt hur tillägg/borttag av ett substrat påverkar biogödselns kvalité. Därutöver har innehållet av kadmium, fosfor och kadmiumfosforkvoten i producerad biogödsel samt i ett urval substrat kartlagts. För biogödsel och för vissa substratkategorier redovisas medel-, maximum- och minimivärden för innehåll av kadmium och fosfor samt kadmium-fosforkvoten. För visa substratkategorier redovisas även medianvärden.

Följande slutsatser kan dras av studien:

• Innehåll av kadmium och fosfor samt kadmiumfosforkvoten varierar mellan biogödsel från olika samrötningsanläggningar.
• De substrat som används för biogas- och biogödselproduktion har generellt ett visst innehåll av kadmium.
• Innehållet av kadmium varierar mycket mellan olika substrat samtidigt som en variation finns inom olika substratkategorier.
• Egna analyser eller analyser utförda av leverantören är att föredra vid beräkningar framför medel-, median- maximum och minimivärden eller typvärden för ett visst substrat.

För att förebygga risken för förhöjda värden av kadmium i biogödseln är det viktigt att arbeta förebyggande och även bedöma substrat utifrån dess innehålla av kadmium och inte enbart biogaspotential. Ensidigt tryck på ökad gasproduktion kan äventyra en hög kvalitet på biogödseln samt möjligheten att återföra växtnäringsämnen.

Biogödseln uppvisar i flera fall lägre kadmiumfosforkvot än stallgödsel. Ett kraftigt sänkt nationellt gränsvärde för kadmiumfosforkvoten (nu 100 mg Cd/kg P) skulle kunna minska möjligheten att använda organiska gödselmedel med dagens kvalitet.

Det långsiktiga målet är att kunskapen om olika substrats innehåll av kadmium och dess påverkan på biogödselkvalitén ska öka samt att biogödselns innehåll av kadmium på sikt ska minska.

The reduction of nitrogen fluxes from land to sea is an important task in areas with estuarine or marine eutrophication. Wetland creation has been proposed as one method to reduce nitrogen from streams draining agricultural areas. In this study, a scenario of nitrogen removal in created wetlands was evaluated by mathematical modelling of nitrogen fluxes in a catchment (224 km2) in southern Sweden. The scenario was based on topographically realistic siting of 40 potential wetlands with a total area of 0.92 km2 (0.4% of the catchment area). Nitrogen removal in the wetlands was described with a simple and robust first-order model, which was modified and evaluated against data from eight monitored surface-flow wetlands. However, the modifications gave no substantial support for changing the basic model. For catchment-scale modelling this wetland model was incorporated into a dynamic process-based catchment model (HBV-N). The catchment was then divided to several coupled subbasins, so that the wetland influence on nitrogen load could be estimated separately for each potential wetland. The modelling showed that the 40 potential wetlands would reduce the nitrogen transport to the coast with approximately 6%. Specific removal rates ranged between 57 and 466 kg ha-1 yr-1 for the different wetlands, depending on residence time (size and hydraulic loading) and nitrogen concentration in inflow. Due to temperature dependence and seasonal variation in water discharge, significant decrease in nitrogen concentrations mainly occurred during summer periods with low loading. The study illustrates that catchment modelling is a useful method for analysing wetland creation plans, and that wetland creation must cover fairly large areas and be combined with other measures in order to achieve substantial reduction of nitrogen fluxes to coastal waters. Further monitoring of existing wetlands will improve the removal expression and decrease uncertainty. For instance, at present it could not be deducted whether wetlands with low average residence times (< 2 days) have net removal or net resuspension on an annual basis. © 2002 Elsevier Science B.V. All rights reserved.

Two crop rotations dominated by spring cereals and grass/clover leys on a clay soil were studied over 2 years with respect to nitrogen (N) and phosphorus (P) leaching associated with pig or dairy slurry application in April, June and October. Leaching losses of total N (TN), total P (TP), nitrate-N and dissolved reactive P (DRP) were determined in separately tile-drained field plots (four replicates). Mean annual DRP leaching after October application of dairy slurry (17 kg P ha-1) to growing grass/clover was 0.37 kg ha-1. It was significantly higher than after October application of pig slurry (13 kg ha-1) following spring cereals (0.16 kg ha-1) and than in the unfertilised control (0.07 kg P ha-1). The proportion of DRP in TP in drainage water from the grass/clover crop rotation (35 %) was higher than from the spring cereal rotation (25 %) and the control (14 %). The grass/clover rotation proved to be very robust with respect to N leaching, with mean TN leaching of 10.5 kg ha-1 year-1 compared with 19.2 kg ha-1 year-1 from the cereal crop rotation. Pig slurry application after cereals in October resulted in TN leaching of 25.7 kg ha-1 compared with 7.0 kg ha-1 year-1 after application to grass/clover in October and 19.1 kg ha-1 year-1 after application to spring cereals in April. In conclusion, these results show that crop rotations dominated by forage leys need special attention with respect to DRP leaching and that slurry application should be avoided during wet conditions or combined with methods to increase adsorption of P to soil particles.

Traditionally, tractors have been built either for tracks or wheels, with tracks mainly on heavy tractors with high power. Today, it is possible to retrofit four separate track units on a conventional agricultural tractor, creating interesting possibilities for agriculture. The objective of the present study was to compare soil compaction and traction for tracks, single and dual wheels mounted on the same tractor type. Measurements were made on two clay soils (Eutric Cambisols) in Sweden in 2009, using an 85kW tractor with a total weight of 7700kg. The rubber track system consisted of four tracks mounted on the conventional wheel axles of the tractor. The measured stresses were similar for the tracks and dual wheels at all depths studied (15, 30 and 50cm), but were considerably higher for the single wheels at all depths. Simulations of soil stresses correlated closely to measured values for the tracks and the dual wheels, but underestimated soil stresses in the topsoil compared to measured values for the single wheel. Bulk density and penetration resistance were consistently highest and saturated hydraulic conductivity lowest after wheeling with single wheels, while there were no statistically significant differences between tracks and dual wheels. With single wheels and the tractor loaded, saturated hydraulic conductivity decreased to 0.01mh-1 from 0.13mh-1 in the control, while bulk density increased from 1.24 to 1.36Mgm-3. The stress distribution in the driving direction was relatively even along the front and rear tracks, which is an advantage compared with a long single track, which often has an uneven longitudinal stress distribution. Slip was significantly higher for the dual and single wheels compared with tracks. To utilise the large contact area of the tracks, the tractor should have a low weight in relation to the engine power. © 2011 Elsevier B.V.

Different strategies for mechanical in-row weed control were evaluated in direct-sown and transplanted bulb onions (Allium cepa) in terms of in-row weeds, labour requirements for hand weeding and marketable yield. Transplanted onions generally performed much better than direct sown onions. The best strategies in transplanted onions decreased the hand weeding time by 70% and increased marketable yield by 96% compared with the best strategies in direct-sown onions. In transplanted onions, one weed harrowing and three in-row cultivations with torsion weeders reduced in-row weed numbers by 85%, reduced hand weeding time by 73%, and caused no yield reduction compared with the normal strategy of one weed harrowing and ordinary inter-row cultivation. In direct-sown onions, pre-emergence flame weeding and repeated torsion weeding reduced hand weeding time by 40% and caused no yield reduction compared with flame weeding and inter-row cultivation. The effectiveness of in-row cultivation was very dependent on the timing of treatments. Using transplanted onions and in-row weed control is a way to ensure high yields and reduce labour requirements for hand weeding compared with direct-sown onions and interrow cultivation. © 2008 A B Academic Publishers.