Effect of manure application timing, crop, and soil type on nitrate leaching

Timing of manure application affects N leaching. This 3-yr study quantified N losses from liquid manure application on two soils, a Muskellunge clay loam and a Stafford loamy sand, as affected by cropping system and timing of application. Dairy manure was applied at an annual rate of 93 800 L ha(-1) on replicated drained plots under continuous maize (Zea mays L.) in early fall, late fall, early spring, and as a split application in early and late spring. Variable rates of supplemental sidedress N fertilizer were applied as needed. Manure was applied on orchardgrass (Dactylis glomerata L.) in split applications in early fall and late spring, and early and late spring, with supplemental N fertilizer topdressed as NH4NO3 in early spring at 75 kg N ha(-1). Drain water was sampled at least weekly when lines were flowing. Three-year FWM (flow-weighted mean) NO3-N concentrations on loamy sand soil averaged 2.5 times higher (12.7 mg L(-1)) than those on clay loam plots (5.2 mg L(-1)), and those for fall applications on maize-cropped land averaged >10 mg L(-1) on the clay loam and >20 mg L(-1) on the loamy sand. Nitrate-N concentrations among application seasons followed the pattern early fall > late fall > early spring = early + late spring. For grass, average NO3-N concentrations from manure application remained well below 10 mg L(-1). Fall manure applications on maize show high NO3-N leaching risks, especially on sandy soils, and manure applications on grass pose minimal leaching concern.     

Mapping ground water vulnerability to pesticide leaching with a process-based metamodel of EuroPEARL

To support EU policy, indicators of pesticide leaching at the European level are required. For this reason, a metamodel of the spatially distributed European pesticide leaching model EuroPEARL was developed. EuroPEARL considers transient flow and solute transport and assumes Freundlich adsorption, first-order degradation and passive plant uptake of pesticides. Physical parameters are depth dependent while (bio)-chemical parameters are depth, temperature, and moisture dependent. The metamodel is based on an analytical expression that describes the mass fraction of pesticide leached. The metamodel ignores vertical parameter variations and assumes steady flow. The calibration dataset was generated with EuroPEARL and consisted of approximately 60,000 simulations done for 56 pesticides with different half-lives and partitioning coefficients. The target variable was the 80th percentile of the annual average leaching concentration at 1-m depth from a time series of 20 yr. The metamodel explains over 90% of the variation of the original model with only four independent spatial attributes. These parameters are available in European soil and climate databases, so that the calibrated metamodel could be applied to generate maps of the predicted leaching concentration in the European Union. Maps generated with the metamodel showed a good similarity with the maps obtained with EuroPEARL, which was confirmed by means of quantitative performance indicators.     

Aerating grassland before manure application reduces runoff nutrient loads in a high rainfall environment

The effect of mechanically aerating grassland before liquid manure application in the fall on surface runoff and transport of nutrients and solids was studied in a high rainfall area. The two treatments were control and aeration, the latter receiving one pass with an aerator perpendicular to the slope before fall application of liquid manure (dairy in Years 1-3 and swine in Year 4). Treatments were randomly assigned on 3 to 5% sloping land with a silt loam surface soil (Aquic Dystroxerept) planted in orchardgrass (Dactylis glomerata L.). Runoff from natural rainfall events was sampled for nutrient and solids analysis. Aeration significantly reduced runoff and loads of suspended solids, total Kjeldahl N (TKN), and dissolved reactive P in all years. Annual runoff amounts were reduced by 47 to 81%, suspended and volatile solid loads by 48 to 69% and 42 to 83%, respectively, TKN loads by 56 to 81%, and total P (TP) loads by 25 to 75%. Loads of the soluble nutrient NH4-N, dissolved reactive P, and K were reduced by 41 to 83%. The first three runoff events after manure application accounted for approximately one-third of the annual total runoff and solid and nutrient loads when averaged across treatments, with loads of TKN, K, and NH4-N totaling 4.4, 3.3, and 1.9 kg ha-1, respectively. Aeration slightly increased downward movement of NO3-N, but not other nutrients in the soil. Thus mechanical aeration can be an effective tool for reducing runoff and loads of solids and nutrients after surface application of liquid manure on sloping grassland.     

Tillage and field scale controls on greenhouse gas emissions

There is a lack of understanding of how associations among soil properties and management-induced changes control the variability of greenhouse gas (GHG) emissions from soil. We performed a laboratory investigation to quantify relationships between GHG emissions and soil indicators in an irrigated agricultural field under standard tillage (ST) and a field recently converted (2 yr) to no-tillage (NT). Soil cores (15-cm depth) were incubated at 25 degrees C at field moisture content and 75% water holding capacity. Principal component analysis (PCA) identified that most of the variation of the measured soil properties was related to differences in soil C and N and soil water conditions under ST, but soil texture and bulk density under NT. This trend became more apparent after irrigation. However, principal component regression (PCR) suggested that soil physical properties or total C and N were less important in controlling GHG emissions across tillage systems. The CO2 flux was more strongly determined by microbial biomass under ST and inorganic N content under NT than soil physical properties. Similarly, N2O and CH4 fluxes were predominantly controlled by NO3- content and labile C and N availability in both ST and NT soils at field moisture content, and NH4+ content after irrigation. Our study indicates that the field-scale variability of GHG emissions is controlled primarily by biochemical parameters rather than physical parameters. Differences in the availability and type of C and N sources for microbial activity as affected by tillage and irrigation develop different levels and combinations of field-scale controls on GHG emissions.     

SAOZ measurements of NO2 at Aberystwyth

We present in this paper fifteen years' measurements, from March 1991 to September 2005, of stratospheric NO2 vertical columns measured by a SAOZ zenith-sky visible spectrometer. The instrument spent most of its time at Aberystwyth, Wales, with occasional excursions to other locations. The data have been analysed with the WinDOAS analysis program with low-temperature high-resolution NO2 cross-sections and fitting a slit function to each spectrum. Because of a change in detector in May 1998 there is some uncertainty about the relative changes before and after this date, which are partially constrained by the results of an intercomparison exercise. However, the effect of the Mt Pinatubo aerosol cloud is very evident in the data from 1991-94, with a decrease of 10% in NO2 in the summer of 1992 (the SAOZ was located in Lerwick, Scotland during the winter of 1991-92 and observed very low NO2 values but these cannot be directly compared to the Aberystwyth data). To focus more on interannual and long-term variations in NO2, a seasonal variation comprising an annual and semi-annual component was fitted to the morning and evening twilight separately from 1995 to the present. This fit yielded average NO2 columns of 4.08 x 10(15) cm(-2) and 2.68 x 10(15) cm(-2) for the evening and morning twilight, respectively, with a corresponding annual amplitude of +/-2.08 x 10(15) cm(-2) and +/-1.50 x 10(15) cm(-2). Departures from the fitted curve show a trend of 6% per decade, consistent with that reported elsewhere, for the period 1998-2003, but in the past two years a distinct interannual variation of amplitude of approximately 8% has emerged.     

Parental supervision and discomfort with children walking to school in low-income communities in Cape Town,South Africa

Objective: The risk of pedestrian injury is compounded for children living in low-income communities due to factors such as poor road and pedestrian infrastructure, reliance on walking as a means of transport, and compromised supervision. Parents play an important role in child pedestrian safety. The primary objective of this study was to examine the effects of child pedestrian variables on parental discomfort with regard to letting their child walk to and from school and on the frequency of adult supervision.

Methods: A cross-sectional study was conducted using a convenience sample from 3 schools participating in a pedestrian safety school initiative. The schools are situated in low-income, high-risk communities in the City of Cape Town. A parent survey form was translated into isiXhosa and sent home with learners to those parents who had consented to participate. The response rate was 70.4%, and only parents of children who walk to and from school were included in the final sample (n = 359). Child pedestrian variables include the time taken to walk to school, parental rating of the child's ability to safely cross the road, and the frequency of adult supervision.

Results: More than half of parents reported that their child walked to and from school without adult supervision. About 56% of children took less than 20 min to walk to school. Most parents (61%) were uncomfortable with their child walking to school, although the majority of parents (55.7%) rated their child's ability to cross the road safely as better or significantly better than average (compared to peers). The parents did not perceive any differences in pedestrian risk factors between boys and girls or between younger (6–9 years) and older (10–15 years) children. The time spent by a child walking to school and parents' perceptions of their child's road-crossing ability were found to be significant predictors of parental discomfort (in letting their child walk). Younger children and children who spent less time walking were more likely to be supervised by an adult.

Conclusions: Many South African schoolchildren have to navigate the roads without adult supervision from a young age. Caregivers, especially in low-income settings, often have limited options with regard to getting their child to school safely. Regardless of the child's age and gender, the time that they spend on the roads is an important factor for parents in terms of pedestrian safety.     

Reducing external costs of nitrogen pollution by relocation of pig production between regions in the European Union

This paper tests the hypothesis that relocation of pig production within the EU27 can reduce the external costs of nitrogen (N) pollution. The external cost of pollution by ammonia and nitrate from agriculture in the European Union (EU27) in 2008 was estimated at 61–215 billion € (0.5 to 1.8% of the GDP). Per capita it ranged from more than 1000 € in north-west EU27 to 50 € in Romania. The average contribution of pig production was 15%. Using provincial data (224 NUTS2 regions in EU27), the potential reduction of external N cost by relocation of pig production was estimated at 14 billion € (10% of the total). Regions most eligible for decreasing the pig stock were in western Germany, Flemish region, Denmark, the Netherlands and Bretagne, while Romania is most eligible for increasing pig production. Relocating 20 million pigs (13% of the total EU stock) decreased average external costs per capita from 900 to 785 € in the 13 NUTS2 regions where pigs were removed and increased from 69 to 107 € in 11 regions receiving pigs. A second alternative configuration of pig production was targeted at reducing exceedance of critical N deposition and closing regional nutrient cycles. This configuration relocates pigs within Germany and France, for example from Bretagne to Northern France and from Weser-Ems to Oberbayern. However, total external cost increases due to an increase of health impacts, unless when combined with implementation of best N management practices. Relocation of the pig industry in the EU27 will meet many socio-economic barriers and realisation requires new policy incentives.     

Simulating and delineating future land change trajectories across Europe

Explorations of future land use change are important to understand potential conflicts between competing land uses, trade-offs associated with particular land change trajectories, and the effectiveness of policies to steer land systems into desirable states. Most model-based explorations and scenario studies focused on conversions in broad land use classes, but disregarded changes in land management or focused on individual sectors only. Using the European Union (EU) as a case study, we developed an approach to identifying typical combinations of land cover and management changes by combining the results of multimodel simulations in the agriculture and forest sectors for four scenarios from 2000 to 2040. We visualized land change trajectories by mapping regional hotspots of change. Land change trajectories differed in extent and spatial pattern across the EU and among scenarios, indicating trajectory-specific option spaces for alternative land system outcomes. In spite of the large variation in the area of change, similar hotspots of land change were observed among the scenarios. All scenarios indicate a stronger polarization of land use in Europe, with a loss of multifunctional landscapes. We analyzed locations subject to change by comparing location characteristics associated with certain land change trajectories. Results indicate differences in the location conditions of different land change trajectories, with diverging impacts on ecosystem service provisioning. Policy and planning for future land use needs to account for the spatial variation of land change trajectories to achieve both overarching and location-specific targets.

     

Characterization of phosphate rock and phosphogypsum from Gabes phosphate fertilizer factories (SE Tunisia): high mining potential and implications for environmental protection

Environmental Science and Pollution Research - Since the establishment of the coastal industrial complex in Gabes city (Gulf of Gabes, SE Tunisia), hundred million tons of untreated phosphogypsum...     

Trace metals in soil and leaves of Jacaranda mimosifolia in Tshwane area,South Africa

Plant and soil have been identified as major sink of pollutants in the environment. We evaluated the reliability of biomonitoring of heavy metals in Tshwane area with the use of leaves of Jacaranda mimosifolia. The concentrations of heavy metals such as Ca, Mg, Fe, Pb, Zn, Cu, Sb were measured in leaves of J. mimosifolia and soils collected from 10 sites in the city of Tshwane during two sampling periods. The metals were analyzed with the use of ICP-MS. The result shows significant differences in the concentration of trace metals in all the sites (p < 0.01). The differences between the two sampling periods were statistically significant (p < 0.01). Concentration of metals from high traffic and industrial sites were significantly higher than in the residential areas (p < 0.01). Concentration factor suggests that translocation of metals from roots to leaves could be relevant only for some metals such as Ca, Mg and Sb. The study reveals an anthropogenic source for the trace metals. Leaves of J. mimosifolia were found to be a useful biomonitor of the determined trace metals.