Copper and zinc recycling in Australia: potential quantities and policy options

This paper presents relevant data for industry and governmental policy makers with the aim of increasing the recycling rate of end-of-life copper and zinc in Australia in a technically and economically feasible way. The methodology used to quantify and spatially distribute end-of-life flows of copper and zinc is based on existing and anticipated in-use stocks, their residence times, and their historical and anticipated future evolution. Australia currently (ca. 2000) generates about 72 Gg/year and 57 Gg/year of end-of-life copper and zinc, respectively. Some 70% of all discarded copper and 40% of all discarded zinc generated in Australia are currently being recycled. A detailed assessment shows that about 75% of all end-of-life material in Australia comes from the three states New South Wales, Victoria, and Queensland. In Australia, about 70–75% of waste copper and waste zinc is generated in urban areas. Residential applications account for about 40% (copper) and 60% (zinc) of the generated discards; commercial and industrial applications account for the remainder. By 2030, the discard flows are predicted to increase by about 105% and 155%, to 150 Gg Cu/year and 145 Gg Zn/year, providing substantially increased opportunities for recovery and re-use. Priority targets for the improvement of copper and zinc recycling in Australia are buildings under renovation, urban infrastructure, the transportation sector, and also consumer and business durables. Urban centres are particularly attractive locations for recycling facilities, especially in Perth and Adelaide.     

Modelled soil organic carbon stocks and changes in the Indo-Gangetic Plains,India from 1980 to 2030

The Global Environment Facility co-financed Soil Organic Carbon (GEFSOC) Project developed a comprehensive modelling system for predicting soil organic carbon (SOC) stocks and changes over time. This research is an effort to predict SOC stocks and changes for the Indian, Indo-Gangetic Plains (IGP), an area with a predominantly rice (Oryza sativa)–wheat (Triticum aestivum) cropping system, using the GEFSOC Modelling System and to compare output with stocks generated using mapping approaches based on soil survey data. The GEFSOC Modelling System predicts an estimated SOC stock for the IGP, India of 1.27, 1.32 and 1.27 Pg for 1990, 2000 and 2030, respectively, in the top 20 cm of soil. The SOC stock using a mapping approach based on soil survey data was 0.66 and 0.88 Pg for 1980 and 2000, respectively. The SOC stock estimated using the GEFSOC Modelling System is higher than the stock estimated using the mapping approach. This is due to the fact that while the GEFSOC System accounts for variation in crop input data (crop management), the soil mapping approach only considers regional variation in soil texture and wetness. The trend of overall change in the modelled SOC stock estimates shows that the IGP, India may have reached an equilibrium following 30–40 years of the Green Revolution. This can be seen in the SOC stock change rates. Various different estimation methods show SOC stocks of 0.57–1.44 Pg C for the study area. The trend of overall change in C stock assessed from the soil survey data indicates that the soils of the IGP, India may store a projected 1.1 Pg of C in 2030.     

Are soils of Iowa USA currently a carbon sink or source? Simulated changes in SOC stock from 1972 to 2007

Upscaling the spatial and temporal changes in carbon (C) stocks and fluxes from sites to regions is a critical and challenging step toward improving our understanding of the dynamics of C sources and sinks over large areas. This study simulated soil organic C (SOC) dynamics within 0–100 cm depth of soils across the state of Iowa in the USA from 1972 to 2007 using the General Ensemble biogeochemical Modeling System (GEMS). The model outputs with variation coefficient were analyzed and assembled from simulation unit to the state scale based upon major land use types at annual step. Results from this study indicate that soils (within a depth of 0–100 cm) in Iowa had been a SOC source at a rate of 190 ± 380 kg C ha^?1 yr^?1. This was likely caused by the installation of a massive drainage system which led to the release of SOC from deep soil layers previously protected under poor drainage conditions. The annual crop rotation was another major force driving SOC variation and resulted in spatial variability of annual budgets in all croplands. Annual rate of change of SOC stocks in all land types depended significantly on the baseline SOC levels; soils with higher SOC levels tended to be C sources, and those with lower levels tended to be C sinks. Management practices (e.g., conservation tillage and residue management practices) slowed down the C emissions from Iowa soils, but could not reverse the general trend of net SOC loss in view of the entire state due mainly to a high level of baseline SOC stocks.     

Carbon stocks in Swiss agricultural soils predicted by land-use,soil characteristics,and altitude

Effects of agricultural land-use and land-use change on soil organic carbon (SOC) pools play an important role in the mitigation of the global greenhouse effect. To estimate these effects, baseline SOC data for individual regions or countries are needed. The aim of this study was to quantify current SOC stocks in Swiss agricultural soils, to identify meaningful predictors for SOC, and to estimate historical SOC losses. SOC stocks in mineral soils were estimated from combined georeferenced data for land-use, topography, and profile data (n=544) from soil surveys. Mean SOC density in the layer 0–20 cm ranged between 40.6±8.9 t ha⁻¹ (±95% confidence interval (CI)) for arable land and 50.7±12.2 t ha⁻¹ for favourable permanent grassland, and in the layer 0–100 cm from 62.9±15.2 t ha⁻¹ for unfavourable grassland to 117.4±29.8 t ha⁻¹ for temporary grasslands (leys). SOC stocks in organic soils were quantified separately for intact and cultivated peatlands using data from peatland inventories and current SOC densities calculated from average peat decay rates. Organic soils account for less than 3% of the total area but store about 28% (47.2±7.3 Mt) of the total SOC stock of 170±17 Mt. Land-use type, clay content, and altitude (serving as a climate proxy for grassland soils at higher altitudes) were identified as main SOC predictors in mineral soils. Clay content explained up to 44% of the variability in SOC concentrations in the fine earth of arable soils, but was not significantly related to SOC in grassland soils at higher altitudes. SOC concentration under permanent grassland increases linearly with altitude, but because soil depth and stone content limit carbon storage in alpine grassland soils, no relationship was found between altitude and SOC stock. A preliminary estimate suggested that about 16% of the national SOC stock has been lost historically due to peatland cultivation, urbanisation, and deforestation. It seems unlikely that future changes in agricultural practices could compensate for this historical SOC loss in Swiss agricultural soils.     

Modeling increased demand of energy for air conditioners and consequent CO2 emissions to minimize health risks due to climate change in India

Developing countries situated mostly in latitudes that are projected for the highest climate change impact in the twenty-first century will also have a predictable increase in demand on energy sources. India presents us with a unique opportunity to study this phenomenon in a large developing country. This study finds that climate adaptation policies of India should consider the significance of air conditioners (A/Cs) in mitigation of human vulnerability due to unpredictable weather events such as heat waves. However, the energy demand due to air conditioning usage alone will be in the range of an extra ～750,000 GWh to ～1,350,000 GWh with a 3.7 °C increase in surface temperatures under different population scenarios and increasing incomes by the year 2100. We project that residential A/C usage by 2100 will result in CO₂ emissions of 592 Tg to 1064 Tg. This is significant given that India's total contribution to global CO₂ emissions in 2009 was measured at 1670 Tg and country's residential and commercial electricity consumption in 2007 was estimated at 145,000 GWh.     

The transport of Cu and Zn from agricultural soils to surface water in a small catchment

Long-term manure-borne copper and zinc inputs (18–324 mg Cu m⁻² yr⁻¹ and 100–800 mg Zn m⁻² yr⁻¹) to grassland soils resulted in their catchment in water concentrations that often exceeded the surface water quality criteria (2 μg Cu l⁻¹ and 5 μg Zn l⁻¹). This paper compares retention and release of Cu and Zn by two types of soil, a mineral soil (MS) and a dark colored soil rich in organic matter (OS). On the basis of dry soil mass, the OS has a higher retention/affinity for Cu and Zn than the MS, but much less Zn accumulated in the MS when compared on an areal basis. This is largely because of the much smaller bulk OS density and larger dissolved metal concentrations in the OS drainage than that for the MS. However, because of the greater water retention capacity of the OS, elevated metal concentrations in the soil solution do not necessarily cause greater loss to water. It is concluded that artificially drained OS can contribute significantly to the observed elevated Cu and Zn concentrations of the river, especially during relatively dry weather conditions when the contribution of water seeping from OS to the total river water discharge becomes increasingly important.     

Comparison of mechanical properties of pure copper welded using friction stir welding and tungsten inert gas welding

The objective of this research is to investigate the mechanical properties including bonding, tensile strength, and impact resistance of pure copper welded using friction stir welding (FSW) method and compare them with that of tungsten inert gas (TIG) welding. Micro-hardness tests are performed on pure copper, TIG welded copper and FSW welded copper to determine the effect of heat on the hardness of welded coppers. Tensile strength tests and notch tensile strength tests are performed to determine the mechanical properties of different weld process.In this experiment, it is found that the notch tensile strength and the notch strength ratio for FSW (212 MPa, 1.10) are significantly higher than those (190 MPa, 1.02) of TIG welding. For the impact tests, the weld zone and heat-affected zone energy absorption values for FSW (2.87 J, 2.25 J) are higher than those (1.32 J, 0 J) of TIG welding. XRD tests are performed to determine components of copper before and after welding process for TIG and FSW.     

Evidence of rich microbial communities in the subsoil of a boreal acid sulphate soil conducive to greenhouse gas emissions

The largest areas of acid sulphate (AS) soils in Europe are located in Finland, where 67,000–130,000 ha of AS soils are in agricultural use. In addition to their acidifying effects on waters, AS soils might be a significant source of greenhouse gases. In this pilot research, carbon and nitrogen content and microbial activity were studied in an AS and a non-AS soil. Large carbon and nitrogen stocks (110 Mg C_org ha^?1 and 15 Mg N_tot ha^?1) as well as high substrate induced respiration (33 μg CO₂–C g^?1h^?1) were found in the C horizons of the AS soil but not in the non-AS soil. High microbial activity in these horizons of the AS soil was further confirmed by the measurement of dehydrogenase activity, basal respiration, the numbers of culturable bacterial cells, and the ratio of culturable to total numbers of cells. Still, the denitrifying enzyme activity was very low in the anaerobic horizons of the AS soil, indicating the prevalence of microbes other than denitrifiers. We suspect that the microbial community originated with the genesis of AS soil and has been supported by the large stocks of accumulated carbon and mineral nitrogen in the C horizons. If these permanently water-saturated subsoils are exposed to oxygen and their microbial activity consequently increases, large carbon and nitrogen stocks are likely to be mobilised, resulting in increased emission of greenhouse gases. Additional studies of boreal AS soils are needed to assess their potential contribution to increases in greenhouse gas fluxes at the local, regional, and global scales.     

Material flows in the life cycle of leather

This paper presents a study on the resource and environmental profile of leather for communicating to the consumers about the environmental burdens of leather products. The results indicate that significant environmental impacts were caused during the tanning and finishing of leather as well as the electricity production and transportation required in the life cycle. The use of fossil fuels in the production of energy has greater impact with increased emissions leading to about 15190 kg CO₂ equivalent of global warming and about 73 kg SO₂ equivalent of acidification while producing 100 m² of leather for shoe uppers. Further resource use of 174 kg of coal, 6.5 kg of fuel oil, 17.4 m³ of water and 348 kg of chemicals of which about 204 kg are hazardous are consumed, and wastewater of about 17 m³, BOD of 55 kg, COD of about 146 kg, TDS of 732 kg and solid waste of about 1445 kg are generated during the life cycle for the production of 100 m² of leather. The total solid waste generated is 1317 kg, out of which about 80% is biodegradable contributed by slaughtering, tanning and finishing stage, 14% is non-biodegradable contributed by tanning, finishing and electricity production stages and 6% is hazardous mainly from tanning and finishing stage of leather.     

Biodiversity,carbon stocks and sequestration potential in aboveground biomass in smallholder farming systems of western Kenya

While Carbon (C) sequestration on farmlands may contribute to mitigate CO₂ concentrations in the atmosphere, greater agro-biodiversity may ensure longer term stability of C storage in fluctuating environments. This study was conducted in the highlands of western Kenya, a region with high potential for agroforestry, with the objectives of assessing current biodiversity and aboveground C stocks in perennial vegetation growing on farmland, and estimating C sequestration potential in aboveground C pools. Allometric models were developed to estimate aboveground biomass of trees and hedgerows, and an inventory of perennial vegetation was conducted in 35 farms in Vihiga and Siaya districts. Values of the Shannon index (H), used to evaluate biodiversity, ranged from 0.01 in woodlots through 0.4–0.6 in food crop plots, to 1.3–1.6 in homegardens. Eucalyptus saligna was the most frequent tree species found as individual trees (20%), in windrows (47%), and in woodlots (99%) in Vihiga and the most frequent in woodlots (96%) in Siaya. Trees represented the most important C pool in aboveground biomass of perennial plants growing on-farm, contributing to 81 and 55% of total aboveground farm C in Vihiga and Siaya, respectively, followed by hedgerows (13 and 39%, respectively) and permanent crop stands (5 and 6%, respectively). Most of the tree C was located in woodlots in Vihiga (61%) and in individual trees growing in or around food crop plots in Siaya (57%). The homegardens represented the second C pool in importance, with 25 and 33% of C stocks in Vihiga and Siaya, respectively. Considering the mean total aboveground C stocks observed, and taking the average farm sizes of Vihiga (0.6 ha) and Siaya (1.4 ha), an average farm would store 6.5 ± 0.1 Mg C farm^?1 in Vihiga and 12.4 ± 0.1 Mg C farm^?1 in Siaya. At both sites, the C sequestration potential in perennial aboveground biomass was estimated at ca. 16 Mg C ha^?1. With the current market price for carbon, the implementation of Clean Development Mechanism Afforestation/Reforestation (CDM A/R) projects seems unfeasible, due to the large number of small farms (between 140 and 300) necessary to achieve a critical land area able to compensate the concomitant minimum transaction costs. Higher financial compensation for C sequestration projects that encourage biodiversity would allow clearer win–win scenarios for smallholder farmers. Thus, a better valuation of ecosystem services should encourage C sequestration together with on-farm biodiversity when promoting CDM A/R projects.     

Integrated environmental assessment of biodiesel production from soybean in Brazil

This paper presents the results of an environmental impact assessment of biodiesel production from soybean in Brazil. In order to achieve this objective, environmental impact indicators provided by Emergy Accounting (EA), Embodied Energy Analysis (EEA) and Material Flow Accounting (MFA) were used. The results showed that for one liter of biodiesel 8.8 kg of topsoil are lost in erosion, besides the cost of 0.2 kg of fertilizers, about 5.2 m² of crop area, 7.33 kg of abiotic materials, 9.0 tons of water and 0.66 kg of air and about 0.86 kg of CO₂ were released. About 0.27 kg of crude oil equivalent is required as inputs to produce one liter of biodiesel, which means an energy return of 2.48 J of biodiesel per Joule of fossil fuel invested. The transformity of biodiesel (3.90E + 05 seJ J^?1) is higher than those calculated for fossil fuels as other biofuels, indicating a higher demand for direct and indirect environmental support. Similarly, the biodiesel emergy yield ratio (1.62) indicates that a very low net emergy is delivered to consumers, compared to alternatives. Obtained results show that when crop production and industrial conversion to fuel are supported by fossil fuels in the form of chemicals, goods, and process energy, the fraction of fuel that can actually be considered renewable is very low (around 31%).     

Comparing intensive,extensified and organic grassland farming in southern Germany by process life cycle assessment

To reduce the environmental burden of agriculture, suitable methods to comprehend and assess the impact on natural resources are needed. One of the methods considered is the life cycle assessment (LCA) method, which was used to assess the environmental impacts of 18 grassland farms in three different farming intensities — intensive, extensified, and organic — in the Allgäu region in southern Germany. Extensified and organic compared with intensive farms could reduce negative effects in the abiotic impact categories of energy use, global warming potential (GWP) and ground water mainly by renouncing mineral nitrogen fertilizer. Energy consumption of intensive farms was 19.1 GJ ha⁻¹ and 2.7 GJ t⁻¹ milk, of extensified and organic farms 8.7 and 5.9 GJ ha⁻¹ along with 1.3 and 1.2 GJ t⁻¹ milk, respectively. Global warming potential was 9.4, 7.0 and 6.3 CO₂-equivalents ha⁻¹ and 1.3, 1.0 and 1.3 CO₂-equivalents t⁻¹ milk for the intensive, extensified and organic farms, respectively. Acidification calculated in SO₂-equivalents was high, but the extensified (119 kg SO₂ ha⁻¹) and the organic farms (107 kg SO₂ ha⁻¹) emit a lower amount compared with the intensive farms (136 kg SO₂ ha⁻¹). Eutrophication potential computed in PO₄-equivalents was higher for intensive (54.2 kg PO₄ ha⁻¹) compared with extensified (31.2 kg PO₄ ha⁻¹) and organic farms (13.5 kg PO₄ ha⁻¹). Farmgate balances for N (80.1, 31.4 and 31.1 kg ha⁻¹) and P (5.3, 4.5 and −2.3 kg ha⁻¹) for intensive, extensified and organic farms, respectively, indicate the different impacts on ground and surface water quality. Analysing the impact categories biodiversity, landscape image and animal husbandry, organic farms had clear advantages in the indicators number of grassland species, grazing cattle, layout of farmstead and herd management, but indices in these categories showed a wide range and are partly independent of the farming system.     

The water footprint of food waste: case study of fresh mango in Australia

In many parts of the world, freshwater is already a scarce and overexploited natural resource, raising concerns about global food security and damage to freshwater ecosystems. This situation is expected to intensify with the FAO estimating that world food production must double by 2050. Food chains must therefore become much more efficient in terms of consumptive water use. For the small and geographically well-defined Australian mango industry, having an average annual production of 44,692 t of marketable fresh fruit, the average virtual water content (sum of green, blue and gray water) at orchard gate was 2298 l kg^?1. However, due to wastage in the distribution and consumption stages of the product life cycle, the average virtual water content of 1 kg of Australian-grown fresh mango consumed by an Australian household was 5218 l. This latter figure compares to an Australian-equivalent water footprint of 217 l kg^?1, which is the volume of direct water use in Australia having an equivalent potential to contribute to water scarcity. Nationally, distribution and consumption waste in the food chain of Australian-grown fresh mango to Australian households represented an annual waste of 26.7 Gl of green water and 16.6 Gl of blue water. These findings suggest that interventions to reduce food chain waste will likely have as great or even greater impact on freshwater resource availability as other water use efficiency measures in agriculture and food production.     

Methane,nitrous oxide and ammonia emissions during storage and after application of dairy cattle slurry and influence of slurry treatment

Slurries are a significant source of CH₄, NH₃ and N₂O emissions to the atmosphere. The research project aimed at quantifying CH₄, NH₃ and N₂O emissions from liquid manure stores and after manure application under field conditions. The influence of the manure treatment options “no treatment”, “slurry separation”, “anaerobic digestion”, “slurry aeration” and “straw cover” on the emission level was investigated. Approximately 10 m³ of differently treated slurry were stored in pilot scale slurry tanks. Emissions were followed for c. 80 days. After the storage period, slurries were applied to permanent grassland. Greenhouse gas emissions from slurry were mainly caused by methane emissions during storage and by nitrous oxide emissions after field application of manures. Mitigation of GHG emissions can be achieved by a reduction in slurry dry matter and easily degradable organic matter content. Ammonia emissions mainly occurred after field application. Untreated slurry emitted 226.8 g NH₃ m⁻³ and 92.4 kg CO₂ eq. m⁻³ (storage and field application). Slurry separation (liquid fraction and composting of the solid fraction) resulted in NH₃ losses of 402.9 g m⁻³ and GHG losses of 58.5 kg CO₂ eq. m⁻³. Anaerobic digestion was a very effective means to reduce GHG emissions. 37.9 kg CO₂ eq. m⁻³ were lost. NH₃ emissions were similar to those from untreated slurry. Covering the slurry store with a layer of chopped straw instead of a wooden cover increased NH₃ emissions to 320.4 g m⁻³ and GHG emissions to 119.7 kg CO₂ eq. m⁻³. Slurry aeration nearly doubled NH₃ emissions compared to untreated slurry. GHG emissions were reduced to 53.3 kg CO₂ eq. m⁻³.     

The Satoyama Index: A biodiversity indicator for agricultural landscapes

Agricultural development to meet rapidly growing demands for food and biofuel and the abandonment of traditional land use have had major impacts on biodiversity. Habitat diversity is one of the most important factors influencing biodiversity in agricultural landscapes. In this study we propose an ecological index of ecosystem or habitat diversity in agricultural landscapes – the Satoyama Index (SI) – that is discernible under appropriate spatial units (e.g., 6 km × 6 km) from 1 km × 1 km gridded land-cover data available from an open-access web site. A high SI value is an indicator of high habitat diversity, which is characteristic of traditional agricultural systems, including Japanese satoyama landscapes, while a low value indicates a monotonic habitat condition typical of extensive monoculture landscapes. The index correlated well with the spatial patterns of occurrence of a bird of prey (Butastur indicus) and species richness of amphibians and damselflies in Japan. The values of the SI also corresponded well to the spatial patterns of typical traditional agricultural landscapes with high conservation value in other countries, for example, the dehesas of the Iberian Peninsula and shade coffee landscapes in Central America. Globally, the pattern of East/South-East Asian paddy belts with their high index values contrasts markedly with the low values of the Eurasian, American, and Australian wheat or corn belts. The SI, which correlates landscapes with biodiversity through potential habitat availability, is highly promising for assessing and monitoring the status of biodiversity irrespective of scale.     

Dairy farm CH4 and N2O emissions,from one square metre to the full farm scale

The greenhouse gas emissions from agricultural systems contribute significantly to the national budgets for most countries in Europe. Measurement techniques that can identify and quantify emissions are essential in order to improve the selection process of emission reduction options and to enable quantification of the effect of such options. Fast box emission measurements and mobile plume measurements were used to evaluate greenhouse gas emissions from farm sites. The box measurement technique was used to evaluate emissions from farmyard manure and several other potential source areas within the farm. Significant (up to 250 g CH₄ m⁻² day⁻¹and 0.4 g N₂O m⁻² day⁻¹) emissions from ditches close to stables on the farm site were found.Plume emission measurements from individual manure storages were performed at three sites. For a manure storage with 1200 m³ dairy slurry in Wageningen emission factors of 11 ± 5 g CH₄ m⁻³ manure day⁻¹ and 14 ± 8 mg N₂O m⁻³ manure day⁻¹ were obtained in February 2002.Mobile plume measurements were carried out during 4 days at distances between 30 and 300 m downwind of 20 different farms. Total farm emissions levels ranged from 14 to 95 kg CH₄ day⁻¹ for these sites. Expressed as emission per animal the levels were 0.7 ± 0.4 kg CH₄ animal⁻¹ day⁻¹ for conventional farms. For three farms that used straw bedding for the animals1.4 ± 0.2 kg CH₄ animal⁻¹ day⁻¹ was obtained. These factors include both respired methane and emission from manure in the stable and the outside storages.For a subset of these farms the CH₄ emission was compared with monthly averaged model emission calculations using FarmGHG. This model calculates imports, exports and flows of all products through the internal chains on the farm using daily time steps. The fit of modelled versus measured data has a slope of 0.97 but r² = 0.27. Measurements and model emission estimates agree well on average, for large farms within 30%. For small farms the differences can be up to a factor of 3. CH₄ emissions during winter seem to be underestimated.     

Indicative assessment of the feasibility of Ni and Au phytomining in Australia

Phytomining involves the extraction of metals from solid and liquid substrates using specially selected hyperaccumulating plants. Phytomining is commercially motivated, the objective being to produce a viable metal yield, at production costs low enough to compete with traditional mining techniques, e.g. heap leaching. In this work we assess the technical feasibility of nickel and gold phytomining in Australia by identifying possible sites, plant species most suited to these regions and methods of recovering the metals from the plants once sequestered. We then investigate the economic viability using published technical and financial models. In the near term, phytomining appears most viable where there are comparatively high metal concentrations around existing mines and mineral processing plants, e.g. near tailings dams or smelters, and in recovering metals from low grade ores considered unprofitable using conventional techniques. Phytomining has the added advantage of improving the quality of the land following completion of the operation. The indicative profitability for a Ni phytomine in Australia is predicted to be ～11,500 AU$/ha/harvest, using the hyperaccumulator Berkheya coddii on nickel rich serpentine soils and with energy generation from the harvested biomass. For Au, a profit of ～26,000 AU$/ha/harvest is predicted using induced accumulation (with thiocyanate) with a crop of Brassica juncea coupled with energy generation from the harvested biomass. In both cases, profitability is most sensitive to the metal price and the extractable metal content.     

Nutrient flows in small-scale peri-urban vegetable farming systems in Southeast Asia—A case study in Hanoi

In many peri-urban areas of Southeast Asia, land use has been transformed from rice-based to more profitable vegetable-based systems in order to meet the increasing market demand. The major management related flows of nitrogen (N), phosphorus (P), potassium (K), copper (Cu) and zinc (Zn) were quantified over a 1-year period for intensive small-scale aquatic and terrestrial vegetable systems situated in two peri-urban areas of Hanoi City, Vietnam. The two areas have different sources of irrigation water; wastewater from Hanoi City and water from the Red River upstream of Hanoi. The first nutrient balances for this region and farming systems are presented. The main sources of individual elements were quantified and the nutrient use efficiency estimated. The environmental risks for losses and/or soil accumulation were also assessed and discussed in relation to long-term sustainability and health aspects.The primary source of nutrient input involved a combination of chemical fertilisers, manure (chicken) and irrigation water. A variable composition and availability of the latter two sources greatly influenced the relative magnitude of the final total loads for individual elements. Despite relatively good nutrient use efficiencies being demonstrated for N (46–86%) and K (66–94%), and to some extent also for P (19–46%), high inputs still resulted in substantial annual surpluses causing risks for losses to surface and ground waters. The surplus for N ranged from 85 to 882 kg ha⁻¹ year⁻¹, compared to P and K which were 109–196 and 20–306 kg ha⁻¹ year⁻¹, respectively. Those for Cu and Zn varied from 0.2 to 2.7 and from 0.6 to 7.7 kg ha⁻¹ year⁻¹, respectively, indicating high risk for soil accumulation and associated transfers through the food chain.Wastewater irrigation contributed to high inputs, and excess use of organic and chemical fertilisers represent a major threat to the soil and water environment. Management options that improve nutrient use efficiency represent an important objective that will help reduce annual surpluses. A sustainable reuse of wastewater for irrigation in peri-urban farming systems can contribute significantly to the nutrient supply (assuming low concentrations of potential toxic or hazardous substances in the water). Nutrient inputs need to be better related to the crop need, e.g. through better knowledge about the nutrient concentrations in the wastewater and improved management of the amount of irrigation water being applied.     

Environmental consequences of different beef production systems in the EU

The aim of this paper is to examine the environmental consequences of beef meat production in the EU, using a life cycle approach. Four beef production systems were studied – three from intensively reared dairy calves and one from suckler herds. According to the results of the analysis, the contributions from the production of 1 kg beef meat (slaughter weight) to global warming, acidification, eutrophication, land use and non-renewable energy use were lower for beef from dairy calves than from suckler herds (16.0–19.9 versus 27.3 kg CO₂e, 101–173 versus 210 g SO₂e, 622–1140 versus 1651 g NO₃e, 16.5–22.7 versus 42.9 m²year, and 41.3–48.2 versus 59.2 MJ, respectively). The breakdown analysis helped identify the key areas in the “cradle to farm gate” beef production system where sustainable management strategies are needed to improve environmental performance. The study also included a sensitivity analysis to preliminarily estimate GHG emissions from beef production systems if land opportunity cost and land use change related to grazing and feed crop production for beef were taken into account. If so, the contribution from the production of 1 kg beef to global warming would increase by a factor of 3.1–3.9, based on a depreciation period of 20 years. This highlights the importance of taking into account the impacts of land use in assessing the environmental impacts of livestock production.     

Linking spatio-temporal variation of crop response with sediment deposition along paddy rice terraces

In tropical mountainous regions of South East Asia, intensive cultivation of annual crops on steep slopes makes the area prone to erosion resulting in decreasing soil fertility. Sediment deposition in the valleys, however, can enhance soil fertility, depending on the quality of the sediments, and influence crop productivity. The aim of the study was to assess (i) the spatio-temporal variation in grain yield along two rice terrace cascades in the uplands of northern Viet Nam, (ii) possible linkage of sediment deposition with the observed variation in grain yield, and (iii) whether spatial variation in soil water or nitrogen availability influenced the obtained yields masking the effect of inherent soil fertility using carbon isotope (¹³C) discrimination and ¹⁵N natural abundance techniques. In order to evaluate the impact of seasonal conditions, fertilizer use and sediment quality on rice performance, ¹⁵N and ¹³C stable isotope compositions of rice leaves and grains taken after harvest were examined and combined with soil fertility information and rice performance using multivariate statistics. The observed grain yields for the non-fertilized fields, averaged over both cascades, accounted for 4.0 ± 1.4 Mg ha^?1 and 6.6 ± 2.5 Mg ha^?1 in the spring and summer crop, respectively, while for the fertilized fields, grain yields of 6.5 ± 2.1 Mg ha^?1 and 6.9 ± 2.1 Mg ha^?1 were obtained. In general, the spatial variation of rice grain yield was strongly and significantly linked to sediment induced soil fertility and textural changes, such as soil organic carbon (r 0.34/0.77 for Cascades 1 and 2, respectively) and sand fraction (r ?0.88/?0.34). However, the observed seasonal alteration in topsoil quality, due to sediment deposition over two cropping cycles, was not sufficient to fully account for spatial variability in rice productivity. Spatial variability in soil water availability, assessed through ¹³C discrimination, was mainly present in the spring crop and was linearly related to the distance from the irrigation channel, and overshadowed in Cascade 2 the expected yield trends based on sediment deposition. Although δ¹⁵N signatures in plants indicated sufficient N uptake, grain yields were not found to be always significantly influenced by fertilizer application. These results showed the importance of integrating sediment enrichment in paddy fields within soil fertility analysis. Furthermore, where the effect of inherent soil fertility on rice productivity is masked by soil water or nitrogen availability, the use of ¹³C and ¹⁵N stable isotopes and its integration with conventional techniques showed potential to enhance the understanding of the influence of erosion – sedimentation and nutrient fluxes on crop productivity, at toposequence level.