P.N.C. Murphy

Mapping wetlands: A comparison of two different approaches for New Brunswick, Canada

Wetlands have an important role in ecosystem function and biodiversity. Effective management of wetlands requires accurate and comprehensive spatial information on location, size, classification, and connectivity in the landscape. Using a GIS, two provincial wetland maps were compared with regard to their areal correspondence across different ecoregions of New Brunswick. The first consisted of discrete wetland units (vector data) derived from aerial photo interpretation. The second consisted of wet areas modeled by a newly developed depth-to-water index with continuous coverage across the landscape (raster data). This index was derived from a digital elevation model and hydrographic data. The relative advantages and disadvantages of the two approaches were assessed. The two maps were generally consistent with most discrete wetland areas (51%–67%) embedded in the 0– 10 cm depth-to-water class, verifying the continuous modeling approach. The continuous model identified a larger wetland area. Much of this additional area consisted of riparian zones and numerous small wetlands (< 1 ha) that were not captured by aerial photo interpretation. Unlike the discrete map, the continuous model showed the hydrological connectivity of wetlands across the landscape. Both approaches revealed that topography was a major control on wetland distribution between ecoregions, with more wetland in ecoregions with flatter topography.

Using the Cartographic Depth-to-Water Index to Locate Small Streams and Associated Wet Areas across Landscapes

With increasing scarcity of natural resources, there is a need to provide resource managers and planners with maps that reliably inform about areas vulnerable to hydrological risks, including areas with ephemeral to intermittent flows. This paper demonstrates that the newly developed Wet-Areas Mapping (WAM) process using LiDAR-based point cloud data addresses some of these needs. This is done by portraying local flow patterns, soil drainage, soil moisture regimes and natural vegetation type across mapped areas in a numerically robust and consistent manner. As a result, WAM-derived maps are useful for surprise-free operations planning in several areas of natural resource planning (forestry, parks and recreation, oil and gas extraction, land reclamation), and also serve as field guides for locating and delineating flow channels, road-stream crossings, wet areas and wetlands.

Evaluating the critical source area concept of phosphorus loss from soils to water-bodies in agricultural catchments

Using data collected from six basins located across two hydrologically contrasting agricultural catchments, this study investigated whether transport metrics alone provide better estimates of storm phosphorus (P) loss from basins than critical source area (CSA) metrics which combine source factors as well. Concentrations and loads of P in quickflow (QF) were measured at basin outlets during four storm events and were compared with dynamic (QF magnitude) and static (extent of highly-connected, poorly-drained soils) transport metrics and a CSA metric (extent of highly-connected, poorly-drained soils with excess plant-available P). Pairwise comparisons between basins with similar CSA risks but contrasting QF magnitudes showed that QF flow-weighted mean TRP (total molybdate-reactive P) concentrations and loads were frequently (at least 11 of 14 comparisons) more than 40% higher in basins with the highest QF magnitudes. Furthermore, static transport metrics reliably discerned relative QF magnitudes between these basins. However, particulate P (PP) concentrations were often (6 of 14 comparisons) higher in basins with the lowest QF magnitudes, most likely due to soil-management activities (e.g. ploughing), in these predominantly arable basins at these times. Pairwise comparisons between basins with contrasting CSA risks and similar QF magnitudes showed that TRP and PP concentrations and loads did not reflect trends in CSA risk or QF magnitude. Static transport metrics did not discern relative QF magnitudes between these basins. In basins with contrasting transport risks, storm TRP concentrations and loads were well differentiated by dynamic or static transport metrics alone, regardless of differences in soil P. In basins with similar transport risks, dynamic transport metrics and P source information additional to soil P may be required to predict relative storm TRP concentrations and loads. Regardless of differences in transport risk, information on land use and management, may be required to predict relative differences in storm PP concentrations between these agricultural basins.

Quantification of phosphorus transport from a karstic agricultural watershed to emerging spring water

The degree to which waters in a given watershed will be affected by nutrient export can be defined as that watersheds nutrient vulnerability. This study applied concepts of specific phosphorus (P) vulnerability to develop intrinsic groundwater vulnerability risk assessments in a 32 km(2) karst watershed (spring zone of contribution) in a relatively intensive agricultural landscape. To explain why emergent spring water was below an ecological impairment threshold, concepts of P attenuation potential were investigated along the nutrient transfer continuum based on soil P buffering, depth to bedrock, and retention within the aquifer. Surface karst features, such as enclosed depressions, were reclassified based on P attenuation potential in soil at the base. New techniques of high temporal resolution monitoring of P loads in the emergent spring made it possible to estimate P transfer pathways and retention within the aquifer and indicated small-medium fissure flows to be the dominant pathway, delivering 52-90% of P loads during storm events. Annual total P delivery to the main emerging spring was 92.7 and 138.4 kg total P (and 52.4 and 91.3 kg as total reactive P) for two monitored years, respectively. A revised groundwater vulnerability assessment was used to produce a specific P vulnerability map that used the soil and hydrogeological P buffering potential of the watershed as key assumptions in moderating P export to the emergent spring. Using this map and soil P data, the definition of critical source areas in karst landscapes was demonstrated.

On-farm treatment of dairy soiled water using aerobic woodchip filters

Dairy soiled water (DSW) is produced on dairy farms through the washing-down of milking parlours and holding areas, and is generally applied to land. However, there is a risk of nutrient loss to surface and ground waters from land application. The aim of this study was to use aerobic woodchip filters to remove organic matter, suspended solids (SS) and nutrients from DSW. This novel treatment method would allow the re-use of the final effluent from the woodchip filters to wash down yards, thereby reducing water usage and environmental risks associated with land spreading. Three replicate 100 m(2) farm-scale woodchip filters, each 1 m deep, were constructed and operated to treat DSW from 300 cows over an 11-month study duration. The filters were loaded at a hydraulic loading rate of 30 L m(-2) d(-1), applied in four doses through a network of pipes on the filter surface. Average influent concentrations of chemical oxygen demand (COD), SS and total nitrogen (TN) of 5750 ± 1441 mg L(-1), 602 ± 303 mg L(-1) and 357 ± 100 mg L(-1), respectively, were reduced by 66, 86 and 57% in the filters. Effluent nutrient concentrations remained relatively stable over the study period, indicating the effectiveness of the filter despite increasing and/or fluctuating influent concentrations. Woodchip filters are a low cost, minimal maintenance treatment system, using a renewable resource that can be easily integrated into existing farm infrastructure.

Phosphorus balance and use efficiency on 21 intensive grass-based dairy farms in the South of Ireland

SUMMARY Given the finite nature of global phosphorus (P) resources, there is an increasing concern about balancing agronomic and environmental impacts from P usage on dairy farms. Data from a 3-year (2009–2011) survey were used to assess farm-gate P balances and P use efficiency (PUE) on 21 intensive grass-based dairy farms operating under the good agricultural practice (GAP) regulations in Ireland. Mean stocking rate (SR) was 2·06 livestock units (LU)/ha, mean P surplus was 5·09 kg/ha, or 0·004 kg P/kg milk solids (MS), and mean PUE was 0·70. Phosphorus imports were dominated by inorganic fertilizer (7·61 kg P/ha) and feeds (7·62 kg P/ha), while exports were dominated by milk (6·66 kg P/ha) and livestock (5·10 kg P/ha). Comparison to similar studies carried out before the introduction of the GAP regulations in 2006 indicated that P surplus, both per ha and per kg MS, has significantly decreased (by 74 and 81%, respectively) and PUE increased (by 48%), mostly due to decreased inorganic fertilizer P import and improvements in P management. There has been a notable shift towards spring application of organic manures, indicating improved awareness of the fertilizer value of organic manures and good compliance with the GAP regulations regarding fertilizer application timing. These results suggested a positive impact of the GAP regulations on dairy farm P surplus and PUE, indicating an improvement in both environmental and economic sustainability of dairy production through improved resource use efficiencies. Such improvements will be necessary to achieve national targets of improved water quality and increased dairy production. Results suggest that optimizing fertilizer and feed P imports combined with improved on-farm P recycling are the most effective way to increase PUE. Equally, continued monitoring of soil test P (STP) and P management will be necessary to ensure that adequate soil P fertility is maintained. Mean P surplus was lower and PUE was much higher than the overall mean surplus (15·92 kg P/ha) and PUE (0·47) from three studies of continental and English dairy farms, largely due to the low import system that is more typical in Ireland, with seasonal milk production (compact spring calving), low use of imported feeds and high use of grazed grass.

Field Measurements of Small Marine Craft Gaseous Emission Factors during NEAQS 2004 and TexAQS 2006

Exhaust emission factors were calculated for a number (n = 116) of small marine craft encountered during the 2004 New England Air Quality Study-International Transport and Chemical Transformation and 2006 Texas Air Quality Study II field campaigns. Emission factors are reported for NO(x), SO(2), and CO in units of grams of pollutant per kilogram of fuel. These factors are compared to emission factors derived from the U.S. Environmental Protection Agency (EPA) NONROAD model, separated into spark-ignition and compression-ignition sources. NO(x) emission factors observed were significantly and substantially higher than predicted by the model by a factor of 2-10. CO emission factors were not significantly different than the model outputs. Because of the correlation between exhaust hydrocarbon and CO for marine craft, it is expected that EPA estimates of hydrocarbon exhaust emission factors are not significantly in error. Small commercial marine craft (e.g., inshore fishing trawlers) are not part of NONROAD, but their measured emission factors were comparable to those of large diesel recreational marine craft in the model.

A modular terrain model for daily variations in machine-specific forest soil trafficability.

A modular approach is presented to assess terrain-specific soil trafficability in terms of soil resistance to penetration and machine-specific rut depths. These modules address: (1) soil resistance to cone penetration (cone index, or CI) as affected by soil moisture, texture and pore space (Module 1), (2) machine-induced rut depths (single-pass and multi-cycles) as affected by wheel loads, tire specifications and CI (accounting for depth of compactable soil, Module 2), (3) temporal variations in hydrothermal conditions, CI, and potential rut depths due to daily soil moisture and temperature variations (Module 3), and (4) spatial variations in CI and rut depth across terrain due to corresponding changes in soil moisture, depth of compactable soil, bulk density, texture, frost depth, organic matter and coarse fragments (Module 4). The approach is applied to off-road wood-forwarding operations. Modules 1 and 2 were calibrated to apply to a wide range of soil conditions. Modules 3 and 4 were initialized for a...

Effect of chemical amendments to dairy soiled water and time between application and rainfall on phosphorus and sediment losses in runoff.

Dairy soiled water (DSW) is a dilute, low nutrient effluent produced on Irish dairy farms through the regular washing down of milking parlours and holding areas. In Ireland, there is no closed period for the land application of DSW except where heavy rain is forecast within 48 h. Chemical amendments have the potential to decrease phosphorus (P) and suspended sediment (SS) loss from DSW applied to land. This study examined the impact of three time intervals (12, 24 and 48 h) between DSW application and rainfall and five treatments (control, unamended DSW, and DSW amended with lime, alum or ferric chloride (FeCl(2))) on P and sediment losses from an intact grassland soil in runoff boxes. Rainfall was simulated at 10.5 ± 1 mm h(-1). Phosphorus concentrations (1-1.6 mg L(-1)) in runoff from DSW application, while not quantitative measures of P loss to surface waters in the field, indicated the importance of incidental P losses and that the current 48 h restriction in Ireland is prudent. Unamended DSW application increased P loss by, on average, 71%, largely due to an increase in particulate phosphorus (PP) loss. All three amendments were effective in decreasing P and SS losses in runoff and, apart from the SS results for lime, were significantly different (p<0.05) to the control at at least one time point. Lime (a 64% reduction in total phosphorus (TP) in comparison with DSW only) was less effective than alum or FeCl(2), likely due to the lower solubility of CaCO(3) in water. Chemical amendment showed potential to decrease P losses from land application of DSW, but the efficacy of such amendments would need to be assessed in field trials and a cost-benefit analysis conducted to further examine whether they could be practically implemented on farms.

Land use: catchment management

Freshwater is a scarce and valuable resource (FAO, 2011). Conservation and equitable distribution of freshwater is therefore critical to sustaining ecosystem services and global food production (Rockstrom et al., 2009). Agriculture uses 70% of global freshwater and so optimizing water use through advanced irrigation, farm, and food processing systems is paramount to meeting the globally increasing demands for food, particularly in the face of a changing climate. With the quantity of freshwater available, all human activities affect the quality of freshwater resources, and degradation of water quality in turn increases the scarcity of freshwater (Peters and Meybeck, 2000). Impaired water quality also limits ecosystem services, and human welfare and livelihood (Ongley, 1996; FAO, 2011). Poor water quality can cause loss of aquatic and riparian biodiversity, ecosystem stability and recreation value, poor human health (e.g., due to unsanitary drinking water and toxins from harmful algal blooms), physical disruption to water supply systems, shellfish contamination, fish kills, and reduced aquaculture production (Carpenter et al., 1998; Schindler, 2006; Withers and Haygarth, 2007; Kay et al., 2009).