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Cantarella, H. and Trivelin, P.C.O. 2001. Determination of inorganic N in soil by the steam-distillation method., In:
Raij, B. van; Andrade J.C., Cantarella H. and Quaggio J.A. (eds), Chemical analysis for the evaluation of fertility of tropical soils, Instituto Agronômico, Campinas pp. 271-276. (In Portuguese).
Trenkel, M.E. 2010. Slow- and controlled-release and stabilized fertilizer: an option for enhancing nutrient efficiency in agriculture. International Fertilizer Industry Association, Paris, France.
Watson, C.J., Akhonzada N.A., Hamilton J.T.G. and Matthews D.I. 2008. Rate and mode of application of the urease inhibitor N-(n-butyl) thiophosphoric triamide on ammonia volatilization from surface-applied urea. Soil Use and Management 24, 246-253.
Douglass, E.A. and Hendrickson, L.L. 1991. HPLC method for the analysis of the urease inhibitor N-(normal-butyl) thiophosphoric triamide and its metabolites. Journal of Agricultural and Food Chemistry 39, 2318-2321.
Nitrogen Workshop 2012
Assessment of national scale groundwater nitrate monitoring data as a basis for evaluating mitigation measures Tedd, K.a, Coxon, C.a, Daly, D.b, Craig, M. b and Misstear, B.c a Department of Geology, Trinity College Dublin, Dublin 2, Ireland b Environmental Protection Agency, Richview, Dublin 14, Ireland c Department of Civil, Structural & Environmental Engineering, Trinity College Dublin, Dublin 2, Ireland
1. Background & Objectives Eutrophication is the principal threat to surface water quality in Ireland. In some situations, groundwater represents a significant pathway for nutrient transport to surface water. Nitrate is usually the principal limiting nutrient responsible for eutrophication in estuarine and coastal waters (Neill, 2005). The interaction of agricultural management practices with soil type, climate, topography and hydrology gives rise to large variation in nutrient concentrations (Cherry et al., 2008). Variation in weather between years adds another layer of complexity and makes it difficult to distinguish the effect of the mitigation method from environmental noise (Lord et al., 2007). In response to the Nitrates Directive (91/676/EEC), Ireland has introduced and reviewed the Nitrates Action Programme via the European Communities (Good Agricultural Practice for Protection of Waters) Regulations 2010. These regulations provide for protection of waters against pollution from agricultural sources. The interim Water Framework Directive (2000/60/EC) (WFD) water quality status assessments were carried out by the Irish Environmental Protection Agency (EPA) in 2008. The assessments found that 41% of Irish estuarine and coastal water bodies (13% by area) are classified as having less than good status, as assessed using multiple biological elements. While very few Irish groundwater bodies (less than 1%) are classified as poor status due to the groundwater bodies failing to meet the drinking water objectives of the WFD, 16% of groundwater bodies are classified as ‘at risk’ owing to the potential deterioration of associated estuarine and coastal water quality by nitrate from groundwater (unpublished EPA data). This risk assessment takes into account the nitrate load from groundwater discharging to rivers reaching the estuarine and coastal water bodies, based on both the groundwater nitrate concentration and the proportion of river flow coming from groundwater (RPS, 2008). The majority of these ‘at risk’ groundwater bodies are in the southeast and southwest of Ireland where elevated nitrate concentrations may provide significant nutrient loading from groundwater to estuarine and coastal waters, either directly or via rivers. National scale groundwater nitrate data were assessed to evaluate factors affecting groundwater quality and status. In particular the relative influence of agricultural management and climate were investigated.
2. Materials & Methods Groundwater nitrate data have been collected in Ireland since the 1970s. Typically, measurements in the 1970s and 1980s were conducted during the course of different projects implemented by the Geological Survey of Ireland or local authorities. In the 1990s, the EPA took responsibility for groundwater monitoring in Ireland and set up a new national monitoring network for groundwater quality and levels. In recent years, and particularly in response to the implementation of the WFD, the groundwater monitoring network in Ireland has been updated and expanded considerably. In the current study, analysis was made of groundwater nitrate data collected from 70 monitoring points within the South East River Basin District (SERBD). Nitrate data from monitoring points within different settings were investigated with respect to pressure layers (including land cover, fertiliser application rates, livestock and septic tank density) and pathway layers (including soils, unconsolidated deposits, bedrock geology and climate data).
Nitrogen Workshop 2012
3. Results & Discussion The average nitrate concentration in the SERBD from 1990 to 2010 is approximately 20 mg NO3 L-1. A few monitoring points show low nitrate concentrations, suggestive of denitrifying conditions, and a few other monitoring points exceed the Drinking Water Directive’s limit of 50 mg NO3 L-1 for nitrate. A considerable proportion of groundwater quality monitoring points show a large variation in nitrate concentrations in recent years (an example may be seen in Figure 1).
Figure 1. Variation in groundwater nitrate concentration in a monitoring point within the Dinantian Pure Bedded Limestones in Co Kilkenny Groundwater nitrate concentrations are likely to have been affected by the above average rainfall in 2008 and 2009; 117% and 125% of the long term annual average was recorded at the Johnstown Castle synoptic station in 2008 and 2009 respectively (Met Eireann, 2009, 2010).
They may also have been influenced by improved agricultural management as a result of the Good Agricultural Practice regulations, which first came into force in 2006.
4. Conclusion In order to accurately assess the impacts of improved agricultural management practices, and to provide for good decision making in the future, it will be important to decouple the impacts of management practices and climate. Further work, utilising additional pathway and pressure data, together with a greater understanding of nitrate transport and attenuation processes, will be important. Good quality groundwater quality monitoring data will provide the basis for this process.
References Cherry, K.A., Shepard, M., Withers, P.J.A. and Mooney, S.J. 2008. Assessing the effectiveness of actions to mitigate nutrient loss from agriculture: a review of methods. Science of the Total Environment 406, 1-23 European Communities (Good Agricultural Practice for Protection of Waters) Regulations 2010. Statutory Instruments No. 610 of 2010. The Stationery Office, Dublin.
Lord, E., Shepherd, M., Silgram, M., Goodlass, G., Gooday, R., and Anthony, S.G. Investigating the effectiveness of NVZ Action Programme measures: development of a strategy for England. Report for DEFRA project WT03017; 2007. 108pp. Available at http://www.defra.gov.uk/science/default.htm.
Met Eireann, 2009. The weather of 2008. Met Eireann, Dublin, Ireland.
Met Eireann, 2010. The weather of 2009. Met Eireann, Dublin, Ireland.
Neil, M. 2005. A method to determine which nutrient is limiting for plant growth in estuarine waters—at any salinity. Marine Pollution Bulletin 50 Pp. 945-955 RPS, 2008. Further Characterisation Study. An integrated approach to quantifying groundwater and surface water contributions of stream flow. Unpublished report.
Nitrogen Workshop 2012
Bedding additives reduce ammonia emissions during storage and after application of cattle straw manure, and improve N utilization by grassland Shah, G.A.a, Rashid, M.I.a, Groot, J.C.J.a, Groot Koerkamp, P.W.G.b, Lantinga, E.A.a a Organic Farming Systems Group, Wageningen University, Droevendaalsesteeg 1, building 107, 6708 PB Wageningen, the Netherlands; bFarm Technology Group, Wageningen University, Bornse Weilanden 9, 6700 AA Wageningen, the Netherlands
1. Background & Objectives Considerable amounts of nitrogen (N) are lost from each phase of the manure management chain (animal housing, manure storage and manure application) as ammonia (NH3) through urea hydrolysis, dissociation and volatilization. However, the control of N losses during one phase could enhance them in subsequent phases (Rotz, 2004). Therefore, it is crucial to develop and evaluate effective measures that can reduce emissions throughout the whole manure management chain and enhance N utilization after land application. The objectives of this study were (i) to quantify the mitigating effects of three promising bedding additives, i.e. zeolite, lava meal and sandy farm topsoil on NH3 emissions during storage and after land application of cattle straw manure, and (ii) to determine total apparent herbage N recovery (ANR) after surface spreading of these manures on grassland.
2. Materials & Methods Three bedding additives were applied inside a naturally ventilated sloping-floor barn proportionally to the daily straw dosage of 5 kg per livestock unit, i.e. 10% of zeolite, 20% of lava meal or 33% of sandy farm topsoil. These proportions were selected after a preliminary trial where the effects of applying various proportions of each additive on NH3 emission from the straw manure beddings were evaluated.
The selection criterion for this was to achieve a remarkable reduction (~80%) compared to the control during the housing phase (results not presented). The trampled-down straw manures were collected daily from the barn for a period of 80 days. The manures were then stockpiled inside a roofed building as four separate heaps: untreated straw manure (control) and straw manure amended with zeolite, lava meal or farm topsoil. Manures were stored for 80 days after the cessation of the collection period. NH 3 emission rates from the heaps were determined by using a flux chamber connected to a photoacoustic gas monitor by two Teflon tubes. The total internal volume of the chamber was 2.12 10-2 m3. At each measurement event, the flux chamber was pressed down 4 to 5 cm deep into the surface of the manure heap. Thereafter, time patterns of NH3 concentration was recorded for 10 to 15 minutes. Actual NH3 emission rates were estimated from the initial slope of the curve between NH3 (gas) concentration (mg m-3) and time (minutes). The measurements were done at two random places on the surface of each manure heap thrice after the end of the collection period. These were stopped when NH3 concentration was reached below the detection limit of the measuring equipment due to the formation of dry crust on the heap surface. After storage, the manures were surface-spread manually on cut grassland in circular plots each with a diameter of 3 m at an application rate of 400 kg N ha-1 according to a randomized complete block design with three replicates. NH3 concentration in the air above each plot was measured immediately after manure spreading by means of three diffusion samplers installed 20 cm above the soil surface in the middle of each plot for 72 hours. The distance between the two adjacent plots was kept at 15 m to avoid NH3 mixing among the treatments. It was assumed that NH3 emission was proportional to the measured average NH3 concentration in the air above each plot. Total dry matter Nitrogen Workshop 2012 (DM) yield over three cuts and ANR from the treatments during the total growth period of five months were determined.
Can leguminous crops reduce nitrous oxide emissions?
Pappa, A.V.a, Thorman, R.b, Benette, G.c, Rees, R.M.a, Sylvester-Bradley, R.b a SAC, West Mains Road, Edinburgh, EH9 3JG, United Kingdom b ADAS Boxworth, Cambridge, CB23 4NN, United Kingdom c ADAS UK Ltd., Gleadthorpe, Meden Vale, Mansfield, Nottingham, NG20 9PF, United Kingdom
1. Background & Objectives There is an urgent global challenge in providing sufficient primary production to sustain a growing population, with increasing demands for foods, feeds and fuels, without exacerbating climate change and other environmental impacts of agriculture (Godfray et al., 2010). Biologically-fixed N from legumes may offer an opportunity to maintain crop production whilst reducing greenhouse gas (GHG) emissions from agricultural systems, partly due to the avoidance of emissions associated with fertiliser manufacture, and partly due to lower field emissions (Rochette and Janzen, 2005).
The objective of this study is to compare the nitrous oxide (N2O) emissions from arable leguminous crops with winter wheat under contrasting climatic conditions.
2. Materials & Methods Experiments in Nottinghamshire, England (loamy sand) and East Lothian, Scotland (sandy loam) tested winter beans, spring beans, combining peas, vining peas and winter wheat in three replicate plots (12 m x 12 m) per treatment, in a completely randomised design (Table 1). N2O flux measurements were made from the first sowing of each crop to harvest and measurements were made of crop yield, crop N uptake, direct N2O emissions at 60 min (five static chambers per plot (40 cm x 40 cm)) and also random N2O measurements at 0, 15, 30, 45 and 60 min of 5 chambers per sampling,, soil moisture, nitrate and ammonium N, and temperature. After harvest, plots were divided (half with residues and half without residues) and intensive sampling followed for four weeks. Measurements will continue until November 2012 biweekly.
Nitrogen Workshop 2012 Figure 1. Cumulative N2O emissions for four pulses and winter wheat at two sites in the UK (Nottinghamshire, Gleathdthorpe and East Lothian, Edinburgh) from the day of sowing to end of July 2011.
4. Conclusions Emissions were generally low throughout the growing season for all crops at both sites. Emissions data are not yet available after harvest but there are indications that residue removal increased emissions from vining peas. It will be important to collate data over 12 months for all crops (available in June 2012), in order to relate contributions of emissions during the growing season to those resulting after harvest and from residue incorporation and make stronger conclusions.