Water-quality issues facing dairy farming: potential natural and built attenuation of nitrate losses in sensitive agricultural catchments
Ranvir Singh
A B and David J. Horne A
+ Author Affiliations
- Author Affiliations
A School of Agriculture and Environment, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
B Corresponding author. Email: r.singh@massey.ac.nz
Animal Production Science 60(1) 67-77 https://doi.org/10.1071/AN19142
Submitted: 12 March 2019 Accepted: 19 June 2019 Published: 11 November 2019
Abstract
Context: Dairy farming will be increasingly scrutinised for its environmental impacts, in particular for its impacts on freshwater quality in New Zealand and elsewhere. Management and mitigation of high nitrate losses is one of the greatest water-quality challenges facing dairy farming in New Zealand and other countries. Management of critical flow pathways and nitrate-attenuation capacity could offer potential solutions to this problem and help maintain dairy-farming productivity, while reducing its water-quality impacts.
Aims: The present paper reviewed the key water-quality issues faced by dairy farming and assessed potential of emerging edge-of-paddock technologies, and catchment-scale nutrient-attenuation practices, to reduce nitrate losses from dairy farming to receiving water bodies.
Methods: We developed a conceptual catchment-scale modelling analysis assessing potential natural and built attenuation of nitrate losses from dairy farming in the Tararua and Rangitikei catchments (located in the lower part of the North Island, New Zealand).
Key results: This exploratory analysis suggests that a reduction of greater than 25% in the river nitrate loads from dairy-farming areas could potentially be achieved by spatially aligning dairy land with areas of high subsurface nitrate-attenuation capacity, and by managing critical flow pathways using innovative edge-of-field technologies such as controlled drainage, drainage-water harvesting for supplemental irrigation, woodchip bioreactors, and constructed wetlands in the study catchments.
Conclusions: The research findings highlighted the potential to better understand, map and effectively utilise existing natural and new built-in nitrate-attenuation capacity to significantly reduce water-quality impacts from dairy farming across environmentally sensitive agricultural catchments. This knowledge and tools could help farmers close the gap between what can be achieved with current, in-field mitigation practises and the nitrogen-loss allocation imposed by regulatory authorities.
Implications: However, the research findings presented here are based on a coarse-scale, conceptual modelling analysis, and therefore further research is recommended to develop tools and practices to better understand, map and effectively utilise existing natural and new built-in nitrogen attenuation capacity at farm-scale to achieve productive and environmentally friendly pastoral dairy farming across agricultural landscapes.
Additional keywords: critical flow pathways, diffuse pollution, drainage management, livestock production, nitrate attenuation, nitrate leaching.
References
Anderson TR, Groffman PM, Kaushal SS, Walter MT (2014) Shallow groundwater denitrification in riparian zones of a headwater agricultural landscape. Journal of Environmental Quality 43, 732–744.| Shallow groundwater denitrification in riparian zones of a headwater agricultural landscape.Crossref | GoogleScholarGoogle Scholar | 25602674PubMed |
Ballantine DJ, Tanner CC (2013) Controlled drainage systems to reduce contaminant losses and optimize productivity from New Zealand pastoral systems. New Zealand Journal of Agricultural Research 56, 171–185.
| Controlled drainage systems to reduce contaminant losses and optimize productivity from New Zealand pastoral systems.Crossref | GoogleScholarGoogle Scholar |
Barkle G, Clough T, Stenger R (2007) Denitrification capacity in the vadose zone at three sites in the Lake Taupo catchment, New Zealand. Australian Journal of Soil Research 45, 91–99.
| Denitrification capacity in the vadose zone at three sites in the Lake Taupo catchment, New Zealand.Crossref | GoogleScholarGoogle Scholar |
Barkle GF, Stenger R, Moorhead B, McKelvey T (2017) Export of nitrogen and phosphorus from artificially drained dairy pastures in the Hauraki Plains. In ‘Science and policy: nutrient management challenges for the next generation’. Occasional report no. 30. (Eds Currie LD, Hedley MJ) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand) Available at http://flrc.massey.ac.nz/publications.html [Verified 15 March 2019]
Camargo JA, Alonso A, Salamanca A (2005) Nitrate toxicity to aquatic animals: a review with new data from freshwater invertebrates. Chemosphere 58, 1255–1267.
| Nitrate toxicity to aquatic animals: a review with new data from freshwater invertebrates.Crossref | GoogleScholarGoogle Scholar | 15667845PubMed |
Carpenter SR, Caraco NF, Correll DL, Howarth RW, Sharpley AN, Smith VH (1998) Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8, 559–568.
| Nonpoint pollution of surface waters with phosphorus and nitrogen.Crossref | GoogleScholarGoogle Scholar |
Christensen CL, Hedley MJ, Hanly JA, Horne DJ (2012) Nitrogen loss mitigation using duration-controlled grazing: filed observations compared to modelled outputs. Proceedings of the New Zealand Grassland Association 74, 115–120.
Christianson L, Bhandari A, Helmers M, Kult K, Sutphin T, Wolf R (2012) Performance evaluation of four field-scale agricultural drainage denitrification bioreactors in Iowa. Transactions of the ASABE 55, 2163–2174.
| Performance evaluation of four field-scale agricultural drainage denitrification bioreactors in Iowa.Crossref | GoogleScholarGoogle Scholar |
Christianson L, Tyndall J, Helmers M (2013) Financial comparison of seven nitrate reduction strategies for Midwestern agricultural drainage. Water Resources and Economics 2–3, 30–56.
| Financial comparison of seven nitrate reduction strategies for Midwestern agricultural drainage.Crossref | GoogleScholarGoogle Scholar |
Clague JC, Stenger R, Clough TJ (2015) Denitrification in the shallow groundwater system of a lowland catchment: a laboratory study. Catena 131, 109–118.
| Denitrification in the shallow groundwater system of a lowland catchment: a laboratory study.Crossref | GoogleScholarGoogle Scholar |
Clague JC, Stenger R, Morgenstern U (2019) The influence of unsaturated zone drainage status on denitrification and the redox succession in shallow groundwater. The Science of the Total Environment 660, 1232–1244.
| The influence of unsaturated zone drainage status on denitrification and the redox succession in shallow groundwater.Crossref | GoogleScholarGoogle Scholar | 30743918PubMed |
Clark M, Roygard J (2008) Land use and land use capability in the Manawatu–Wanganui region: Technical report to support policy development. Report no. 2008/INT/616, Horizons Regional Council, Palmerston North, New Zealand.
Clark DA, Macdonald KA, Glassey CB, Roach CG, Woodward SL, Griffiths WM, Neal MB, Shepherd MA (2019) Production and profit of current and future dairy systems using differing nitrogen leaching mitigation methods: the Pastoral 21 experience in Waikato. New Zealand Journal of Agricultural Research.
| Production and profit of current and future dairy systems using differing nitrogen leaching mitigation methods: the Pastoral 21 experience in Waikato.Crossref | GoogleScholarGoogle Scholar |
Collins R, McLeod M, Hedley M, Donnison A, Close M, Hanly J, Horne D, Ross C, Davies-Colley R, Bagshaw C, Mathews L (2007) Best management practices to mitigate faecal contamination by livestock of New Zealand waters. New Zealand Journal of Agricultural Research 50, 267–278.
| Best management practices to mitigate faecal contamination by livestock of New Zealand waters.Crossref | GoogleScholarGoogle Scholar |
Collins S, Singh R, Rivas A, Palmer A, Horne D, Manderson A, Roygard J, Matthews A (2017) Transport and potential attenuation of nitrogen in shallow groundwater in the lower Rangitikei catchment, New Zealand. Journal of Contaminant Hydrology 206, 55–66.
| Transport and potential attenuation of nitrogen in shallow groundwater in the lower Rangitikei catchment, New Zealand.Crossref | GoogleScholarGoogle Scholar | 29033220PubMed |
Dairy NZ (2018) ‘New Zealand dairy statistics 2017–18.’ (DairyNZ: Hamilton, New Zealand) Available at https://www.dairynz.co.nz/media/5790451/nz-dairy-statistics-2017-18.pdf [Verified 21 February 2018]
Davies-Colley RJ (2013) River water quality in New Zealand: an introduction and overview. In ‘Ecosystem services in New Zealand: conditions and trends’. (Ed. JR Dymond) pp. 432–447. (Manaaki Whenua Press: Lincoln, New Zealand)
Davis JR, Koop K (2006) Eutrophication in Australian rivers, reservoirs and estuaries: a southern hemisphere perspective on the science and its implication. Hydrobiologia 559, 23–76.
| Eutrophication in Australian rivers, reservoirs and estuaries: a southern hemisphere perspective on the science and its implication.Crossref | GoogleScholarGoogle Scholar |
Di H, Cameron K (2002) Nitrate leaching in temperate agroecosystems: sources, factors, and mitigating strategies. Nutrient Cycling in Agroecosystems 64, 237–256.
| Nitrate leaching in temperate agroecosystems: sources, factors, and mitigating strategies.Crossref | GoogleScholarGoogle Scholar |
Drury CF, Oloya TO, Gaynor JD, Welacky TW, Tan CS, Reynolds WD (2009) Managing tile drainage, subirrigation, and nitrogen fertilization to enhance crop yields and reduce nitrate loss. Journal of Environmental Quality 38, 1193–1204.
| Managing tile drainage, subirrigation, and nitrogen fertilization to enhance crop yields and reduce nitrate loss.Crossref | GoogleScholarGoogle Scholar | 19398517PubMed |
Elliott AH, Alexander RB, Schwarz GE, Shankar U, Sukias JPS, McBride GB (2005) Estimation of nutrient transport and sources for New Zealand using the hybrid mechanistic-statistical model SPARROW. Journal of Hydrology. New Zealand 44, 1–27.
Elwan A, Singh R, Horne D, Roygard J, Clothier B (2015) Nitrogen attenuation factor: can it tell a story about nutrients in different subsurface environments? In ‘Moving farm systems to improved nutrient attenuation’. Occasional report no. 28. (Eds LD Currie LD, LL Burkitt) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand). Available at http://flrc.massey.ac.nz/publications.html [Verified 15 March 2019]
Elwan A, Singh R, Horne D, Manderson A, Roygard J, Clothier B, Jones G (2019) Spatial modelling of nitrogen attenuation capacity and land-based nitrogen loads to rivers. Journal of Environmental Management.
Fausey NR, Allred BJ, Clevenger WB, Brown LC (2003) Recycling runoff and drainage water. Paper number 032166. In ‘2003 ASAE annual meeting’, St Joseph, MI, USA.
Gachango FG, Pedersen SM, Kjaergarard C (2015) Cost-effectiveness analysis of surface flow constructed wetlands (SFCW) for nutrient reduction in drainage discharge from agricultural fields in Denmark. Environmental Management 56, 1478–1486.
| Cost-effectiveness analysis of surface flow constructed wetlands (SFCW) for nutrient reduction in drainage discharge from agricultural fields in Denmark.Crossref | GoogleScholarGoogle Scholar | 26239649PubMed |
Gilliam JW, Skaggs RW, Weed SB (1979) Drainage control to diminish nitrate loss from agricultural fields. Journal of Environmental Quality 8, 137–142.
| Drainage control to diminish nitrate loss from agricultural fields.Crossref | GoogleScholarGoogle Scholar |
Gillingham AG, Thorrold BS (2000) A review of New Zealand research measuring phosphorus in runoff from pasture. Journal of Environmental Quality 29, 88–96.
| A review of New Zealand research measuring phosphorus in runoff from pasture.Crossref | GoogleScholarGoogle Scholar |
Goeller BC, Febria MC, Warburton HJ, Hogsden KL, Collins KE, Devlin HS, Harding JS, McIntosh AR (2019) (2019. Springs drive downstream nitrate export from artificially-drained agricultural headwater catchments. The Science of the Total Environment 671, 119–128.
| (2019. Springs drive downstream nitrate export from artificially-drained agricultural headwater catchments.Crossref | GoogleScholarGoogle Scholar | 30928741PubMed |
Haynes RJ, Williams PH (1993) Nutrient cycling and soil fertility in the grazed pasture ecosystem. Advances in Agronomy 49, 119–199.
| Nutrient cycling and soil fertility in the grazed pasture ecosystem.Crossref | GoogleScholarGoogle Scholar |
Heron DW (custodian) (2014) ‘Geological map of New Zealand 1 : 250 000.’ (GNS Science Geological Map 1: Lower Hutt, New Zealand)
Hickey CW, Martin ML (2009) A review of nitrate toxicity to freshwater species. Report no. R09/57A. Technical report prepared for Environment Canterbury, Christchurch, New Zealand.
Højberg AL, Hansen AL, Wachniew P, Żurek AJ, Virtanen S, Arustiene J, Strömqvist J, Rankinen K, Refsgaard JC (2017) Review and assessment of nitrate reduction in groundwater in the Baltic Sea Basin. Journal of Hydrology. Regional Studies 12, 50–68.
| Review and assessment of nitrate reduction in groundwater in the Baltic Sea Basin.Crossref | GoogleScholarGoogle Scholar |
Hudson N, McKergow L, Tanner C, Baddock E, Burger D, Scandrett J (2018) Denitrification bioreactor work in Waituna Lagoon catchment, Southland. In ‘Farm environmental planning: science, policy and practice’. Occasional report no. 31. (Eds LD Currie LD, CL Christensen) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand) Available at http://flrc.massey.ac.nz/publications.html [Verified 15 March 2019]
Jahangir MMR, Johnston P, Khalil M, Richards K (2012) Linking hydrogeochemistry to nitrate abundance in groundwater in agricultural settings in Ireland. Journal of Hydrology 448–449, 212–222.
| Linking hydrogeochemistry to nitrate abundance in groundwater in agricultural settings in Ireland.Crossref | GoogleScholarGoogle Scholar |
Jahangir MMR, Johnston P, Addy K, Khalil M, Groffman P, Richards K (2013) Quantification of in situ denitrification rates in groundwater below an arable and a grassland system. Water, Air, and Soil Pollution 224, 1693
| Quantification of in situ denitrification rates in groundwater below an arable and a grassland system.Crossref | GoogleScholarGoogle Scholar |
Jha N, Singh R, McMillan AMS (2018) Efficacy of subsurface denitrification to attenuate nitrate in shallow groundwater. In ‘Farm environment planning: science, policy and practice’. Occasional report no. 31. (Eds LD Currie, CL Christensen) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand) Available at http://flrc.massey.ac.nz/publications.html [Verified 15 March 2019]
Joel A, Wesstrom I, Messing I (2009) Mapping suitability of controlled drainage using spatial information of topography, land use and soil type, and validation using detailed mapping, questionnaire and field survey. Hydrology Research 40, 406–419.
| Mapping suitability of controlled drainage using spatial information of topography, land use and soil type, and validation using detailed mapping, questionnaire and field survey.Crossref | GoogleScholarGoogle Scholar |
Kliewer BA, Gilliam JW (1995) Water table management effects on denitrification and nitrous oxide evolution. Soil Science Society of America Journal 59, 1694–1701.
| Water table management effects on denitrification and nitrous oxide evolution.Crossref | GoogleScholarGoogle Scholar |
Korom S (1992) Natural denitrification in the saturated zone: a review. Water Resources Research 28, 1657–1668.
| Natural denitrification in the saturated zone: a review.Crossref | GoogleScholarGoogle Scholar |
Ledgard SF, Penno JW, Sprosen MS (1999) Nitrogen inputs and losses from clover/grass pastures grazed by dairy cows, as affected by nitrogen fertilizer application. Journal of Agricultural Science, Cambridge 132, 215–225.
| Nitrogen inputs and losses from clover/grass pastures grazed by dairy cows, as affected by nitrogen fertilizer application.Crossref | GoogleScholarGoogle Scholar |
Mackay AD, Budding PJ, Morton J (2008) Impact of irrigation on pasture production on two sheep and beef farms in the central Wairarapa. Proceedings of the New Zealand Grassland Association 70, 189–195.
Manderson A (2018) Mapping the extent of artificial drainage in New Zealand. Report prepared for Lincoln Agritech. Contract report LC2690, Manaaki Whenua Landcare Research, Palmerston North, New Zealand.
Martin T, Kaushik N, Trevors J, Whiteley H (1999) Review: denitrification in temperate climate riparian zones. Water, Air, and Soil Pollution 111, 171–186.
| Review: denitrification in temperate climate riparian zones.Crossref | GoogleScholarGoogle Scholar |
McAleer EB, Coxon CE, Richards KG, Jahangir MMR, Grant J, Mellander PE (2017) Groundwater nitrate reduction versus dissolved gas production: a tale of two catchments. The Science of the Total Environment 586, 372–389.
| Groundwater nitrate reduction versus dissolved gas production: a tale of two catchments.Crossref | GoogleScholarGoogle Scholar | 28228237PubMed |
McDowell R, Wilcock B, Hamilton D (2013) Assessment of strategies to mitigate the impact or loss of contaminants from agricultural land to fresh waters. A technical report prepared from Ministry for Environment, RE500/2013/066, Wellington, New Zealand.
McDowell RW, Hedley MJ, Pletnyakov P, Rissmann C, Catto W, Patrick W (2019) Why are median phosphorus concentrations improving in New Zealand streams and rivers? Journal of the Royal Society of New Zealand.
| Why are median phosphorus concentrations improving in New Zealand streams and rivers?Crossref | GoogleScholarGoogle Scholar |
Monaghan RM, Smith LC (2004) Minimising surface water pollution resulting from farm-dairy effluent application to mole-pipe drained soils. II. The contribution of preferential flow of effluent to whole-farm pollutant losses in subsurface drainage from a West Otago dairy farm. New Zealand Journal of Agricultural Research 47, 417–428.
| Minimising surface water pollution resulting from farm-dairy effluent application to mole-pipe drained soils. II. The contribution of preferential flow of effluent to whole-farm pollutant losses in subsurface drainage from a West Otago dairy farm.Crossref | GoogleScholarGoogle Scholar |
Monaghan RM, Paton RJ, Smith LC, Binet C (2000) Nutrient losses in drainage and surface runoff from a cattle-grazed pasture in Southland. Proceedings of the New Zealand Grassland Association 62, 99–104.
Monaghan RM, Hedley MJ, Di HJ, McDowell RW, Cameron KC, Ledgard SF (2007) Nutrient management in New Zealand pastures: recent developments and future issues. New Zealand Journal of Agricultural Research 50, 181–201.
| Nutrient management in New Zealand pastures: recent developments and future issues.Crossref | GoogleScholarGoogle Scholar |
Monaghan RM, Smith LC, Muirhead RW (2016) Pathways of contaminant transfers to water from an artificially-drained soil under intensive grazing by dairy cows. Agriculture, Ecosystems & Environment 220, 76–88.
| Pathways of contaminant transfers to water from an artificially-drained soil under intensive grazing by dairy cows.Crossref | GoogleScholarGoogle Scholar |
Newsome PFJ, Wilde RH, Willoughby EJ (2008) ‘Land and resource information system spatial data layers: data dictionary.’ (Landcare Research: Palmerston North, New Zealand)
NPS–FM (2017) ‘National policy statement for freshwater management 2014 (amended 2017).’ (Ministry for the Environment: Wellington, New Zealand) Available at http://www.mfe.govt.nz/sites/default/files/media/Fresh%20water/nps-freshwater-ameneded-2017_0.pdf [Verified 22 February 2019]
PCE NZ (2013) ‘Water quality in New Zealand: land use and nutrient pollution.’ (Parliamentary Commissioner for the Environment: Wellington, New Zealand). Available at https://www.pce.parliament.nz/media/1275/pce-water-quality-land-use-web-amended.pdf [Verified 20 February 2019]
PCE NZ (2012) ‘Water quality in New Zealand: understanding the science.’ (Parliamentary Commissioner for the Environment: Wellington, New Zealand). Available at https://www.pce.parliament.nz/publications/water-quality-in-new-zealand-understanding-the-science [Verified 20 February 2019]
Pearson L (2015) Artificial subsurface drainage in Southland. Technical report, publication no. 2015-07, Environment Southland, Invercargill, New Zealand.
Rivas A, Singh R, Horne D, Roygard J, Matthews A, Hedley MJ (2017) Denitrification potential in the subsurface environment in the Manawatu River catchment, New Zealand: indications from oxidation-reduction conditions, hydrogeological factors, and implications for nutrient management. Journal of Environmental Management 197, 476–489.
| Denitrification potential in the subsurface environment in the Manawatu River catchment, New Zealand: indications from oxidation-reduction conditions, hydrogeological factors, and implications for nutrient management.Crossref | GoogleScholarGoogle Scholar | 28412619PubMed |
Rivas A, Barkle G, Moorhead B, Clague J, Stenger R (2019) Nitrate removal efficiency and secondary effects of a woodchip bioreactor for the treatment of agricultural drainage. In ‘Nutrient loss mitigations for compliance in agriculture’. Occasional report no. 32. (Eds LD Currie, CL Christensen) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand) Available at http://flrc.massey.ac.nz/publications.html [Verified 15 March 2019]
Rivett M, Buss S, Morgan P, Smith J, Bemment C (2008) Nitrate attenuation in groundwater: a review of biogeochemical controlling processes. Water Research 42, 4215–4232.
| Nitrate attenuation in groundwater: a review of biogeochemical controlling processes.Crossref | GoogleScholarGoogle Scholar | 18721996PubMed |
Roygard JKF, McArthur KJ, Clark ME (2012) Diffuse contributions dominate over point sources of soluble nutrients in two sub-catchments of the Manawatu River, New Zealand. New Zealand Journal of Marine and Freshwater Research 46, 219–241.
| Diffuse contributions dominate over point sources of soluble nutrients in two sub-catchments of the Manawatu River, New Zealand.Crossref | GoogleScholarGoogle Scholar |
Scarsbrook MR, Melland AR (2015) Dairying and water quality issues in Australia and New Zealand. Animal Production Science 55, 856–868.
| Dairying and water quality issues in Australia and New Zealand.Crossref | GoogleScholarGoogle Scholar |
Schipper LA, Vojvodic-Vukovic M (2001) Five years of nitrate removal, denitrification, and carbon dynamics in a denitrification wall. Water Research 35, 3473–3477.
| Five years of nitrate removal, denitrification, and carbon dynamics in a denitrification wall.Crossref | GoogleScholarGoogle Scholar | 11547870PubMed |
Seitzinger S, Harrison JA, Bohlke JK, Bouwman AF, Lowrance R, Peterson B, Tobias C, Van Drecht G (2006) Denitrification across landscapes and waterscapes: a synthesis. Ecological Applications 16, 2064–2090.
| Denitrification across landscapes and waterscapes: a synthesis.Crossref | GoogleScholarGoogle Scholar | 17205890PubMed |
Selbie DR, Buckthought LE, Shepherd MA (2015) The challenge of the urine patch for managing nitrogen in grazed pasture systems. Advances in Agronomy 129, 229–292.
| The challenge of the urine patch for managing nitrogen in grazed pasture systems.Crossref | GoogleScholarGoogle Scholar |
Shepherd M, Phillips P, Snow V, Glassey C (2010) Mitigating nitrate leaching in dairy systems: which periods of urine deposition should we be targeting? In ‘Farming’s future: minimising footprints and maximising margins’. Occasional report no. 23. (Eds LD Currie, CL Lindsay) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand)
Singh R, Elwan A, Horne D, Manderson A, Patterson M, Roygard J (2017a) Predicting land-based nitrogen loads and attenuation in the Rangitikei River catchment: the model development. In ‘Science and policy: nutrient management challenges for the next generation’. Occasional report no. 30. (Eds LD Currie, MJ Hedley) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand). Available at http://flrc.massey.ac.nz/publications.html [Verified 15 March 2019]
Singh R, Elwan A, Horne D (2017b) Nitrogen accounting in the Rangitikei catchment. A technical report prepared for the Horizons Regional Council, Fertilizer and Lime Research Centre, Massey University, Palmerston North, New Zealand.
Singleton PL, McLay CDA, Barkle GF (2001) Nitrogen leaching from soil lysimeters irrigated with dairy shed effluent and with managed drainage. Australian Journal of Soil Research 39, 385–396.
| Nitrogen leaching from soil lysimeters irrigated with dairy shed effluent and with managed drainage.Crossref | GoogleScholarGoogle Scholar |
Skaggs RW, Brevé MA, Gilliam JW (1994) Hydrologic and water quality impacts of agricultural drainage. Critical Reviews in Environmental Science and Technology 24, 1–32.
| Hydrologic and water quality impacts of agricultural drainage.Crossref | GoogleScholarGoogle Scholar |
Smith G, Singh R, Matthews A (2017) Assessing farm-scale nutrient flow pathways and nitrate attenuation in Rangitikei Sand Country. In ‘Science and policy: nutrient management challenges for the next generation’. Occasional report no. 30. (Eds LD Currie, MJ Hedley) (Fertilizer and Lime Research Centre, Massey University: Palmerston North, New Zealand) Available at http://flrc.massey.ac.nz/publications.html [Verified 15 March 2019]
Spalding RF, Parrott JD (1994) Shallow groundwater denitrification. The Science of the Total Environment 141, 17–25.
| Shallow groundwater denitrification.Crossref | GoogleScholarGoogle Scholar |
Starr RC, Gillham RW (1993) Denitrification and organic carbon availability in two aquifers. Ground Water 31, 934–947.
| Denitrification and organic carbon availability in two aquifers.Crossref | GoogleScholarGoogle Scholar |
Stenger R, Barkle G, Burgess C, Wall A, Clague J (2008) Low nitrate contamination of shallow groundwater in spite of intensive dairying: the effect of reducing conditions in the vadose zone-aquifer continuum. Journal of Hydrology. New Zealand 47, 1–24.
Stenger R, Clague JC, Morgenstern U, Clough TJ (2018) Vertical stratification of redox conditions, denitrification and recharge in shallow groundwater on a volcanic hillslope containing relict organic matter. The Science of the Total Environment 639, 1205–1219.
| Vertical stratification of redox conditions, denitrification and recharge in shallow groundwater on a volcanic hillslope containing relict organic matter.Crossref | GoogleScholarGoogle Scholar | 29929288PubMed |
Tan CS, Zhang TQ, Drury CF, Reynolds WD, Oloya T, Gaynor JD (2007) Water quality and crop production improvement using a wetland-reservoir and draining/subsurface irrigation system. Canadian Water Resources Journal 32, 129–136.
| Water quality and crop production improvement using a wetland-reservoir and draining/subsurface irrigation system.Crossref | GoogleScholarGoogle Scholar |
Tanner CC, Sukias JPS (2011) Multi-year nutrient removal performance of three constructed wetlands intercepting drainage flows from intensively grazed pastures. Journal of Environmental Quality 40, 620–633.
| Multi-year nutrient removal performance of three constructed wetlands intercepting drainage flows from intensively grazed pastures.Crossref | GoogleScholarGoogle Scholar | 21520769PubMed |
Tanner CC, Nguyen ML, Sukias JPS (2005a) Nutrient removal by a constructed wetland treating subsurface drainage from grazed dairy pasture. Agriculture, Ecosystems & Environment 105, 145–162.
| Nutrient removal by a constructed wetland treating subsurface drainage from grazed dairy pasture.Crossref | GoogleScholarGoogle Scholar |
Tanner CC, Nguyen ML, Sukias JPS (2005b) Constructed wetland attenuation of nitrogen exported in subsurface drainage from irrigated and rain-fed dairy pastures. Water Science and Technology 51, 55–61.
| Constructed wetland attenuation of nitrogen exported in subsurface drainage from irrigated and rain-fed dairy pastures.Crossref | GoogleScholarGoogle Scholar | 16042243PubMed |
Thayalakumaran T, Bristow K, Charlesworth P, Fass T (2008) Geochemical conditions in groundwater systems: implications for the attenuation of agricultural nitrate. Agricultural Water Management 95, 103–115.
| Geochemical conditions in groundwater systems: implications for the attenuation of agricultural nitrate.Crossref | GoogleScholarGoogle Scholar |
Thornton PK (2010) Livestock production: recent trends, future prospects. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 365, 2853–2867.
| Livestock production: recent trends, future prospects.Crossref | GoogleScholarGoogle Scholar | 20713389PubMed |
United Nations (UN) (2016) ‘Towards a worldwide assessment of freshwater quality: a UN-water analytical brief.’ (UN-Water Technical Advisor Unit: Geneva, Switzerland)
Wales WJ, Kolver ES (2017) Challenges of feeding dairy cows in Australia and New Zealand. Animal Production Science 57, 1366–1383.
| Challenges of feeding dairy cows in Australia and New Zealand.Crossref | GoogleScholarGoogle Scholar |
Ward MH, Jones RR, Brender JD, de Kok TM, Weyer PJ, Nolan BT, Villanueva CM, van Breda SG (2018) Drinking water nitrate and human health: an updated review. International Journal of Environmental Research and Public Health 15, 1557
| Drinking water nitrate and human health: an updated review.Crossref | GoogleScholarGoogle Scholar |
Wesström I, Joel A (2010) Storage and reuse of drainage water. In ‘Proceedings of the 9th international drainage symposium’, 13–16 July 2010, Quebec City, Canada. Paper no. IDS-CSBE-100159. Available at https://elibrary.asabe.org/azdez.asp?JID=5&AID=32140&CID=ids2010&T=1 [Verified 3 September 2019]
Wheeler DM, Ledgard SF, de Klein CAM, Monaghan RM, Carey PL, McDowell RW, Johns KL (2003) OVERSEER® nutrient budgets: moving towards on-farm resource accounting. Proceedings of the New Zealand Grassland Association 65, 191–194.
Wilcock RJ, Monaghan RM, Quinn JM, Srinivasan MS, Houlbrooke DJ, Duncan MJ, Wright-Stow AW, Scarsbrook MR (2013) Trends in water quality of five dairy farming streams in response to adoption of best practice and benefits of long term monitoring at the catchment scale. Marine and Freshwater Research 64, 401–412.
| Trends in water quality of five dairy farming streams in response to adoption of best practice and benefits of long term monitoring at the catchment scale.Crossref | GoogleScholarGoogle Scholar |
