The potential of using alternative pastures, forage crops and gibberellic acid to mitigate nitrous oxide emissions
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In grazed pastures, nitrous oxide (N2O), a powerful greenhouse gas and an ozone depletion substance, is mostly emitted from animal excreta, particularly animal urine-N returned to the soil during grazing. We conducted a series of four field lysimeter and plot experiments to assess the potential of using gibberellic acid (GA) and/or alternative pastures or forage crops to mitigate N2O emissions from outdoor dairy farming systems.
Materials and methods
Pasture and forage plants assessed in the experiments included Italian ryegrass (Lolium multiflorum L.), lucerne (Medicago sativa L.), diverse pastures (including plantain (Plantago lanceolata L.), chicory (Cichorium intybus L.), perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.)), fodder beet (Beta vulgaris L.), kale (Brassica oleracea L.), as well as the standard perennial ryegrass and white clover (RG/WC) pastures. N2O was determined using a standard static chamber method in the field either on top of lysimeters or field plots.
Results and discussion
The results showed that the application of GA to urine-treated lysimeters with Italian ryegrass, lucerne or RG/WC pastures did not result in lower N2O emissions. However, the use of diverse pastures which included plantain with a lower urine-N loading rate at about 500 kg N ha−1 significantly decreased N2O emissions by 46 % compared with standard RG/WC with a urine-N loading rate at 700 kg N ha−1. However, when urine-N was applied at the same rates (at 500 or 700 kg N ha−1), the N2O emissions were similar between the diverse and the standard RG/WC pastures. This would indicate that it is the N-loading rate in the urine from the different pastures that determines the N2O emissions from different pastures or forages, rather than the plants per se. The N2O emissions from cow urine from fodder beet were 39 % lower than from kale with the same urine-N application rate (300 kg N ha−1).
These results suggest that N2O emissions can potentially be reduced by incorporating diverse pastures and fodder beet into the grazed pasture farm system. Further studies on possible mechanisms for the lower N2O emissions from the different pastures or forages would be useful.
KeywordsDiverse pastures Fodder beet Forage crops Gibberellic acid Italian ryegrass Kale Nitrous oxide emissions Perennial ryegrass Plantain White clover
This work was funded by the New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC) and Ministry for Primary Industries (MPI). Permission for access to allied research programmes funded by the Pastoral 21 Consortium (including The Ministry of Business, Innovation and Employment (MBIE), Fonterra, DairyNZ, and Beef and Lamb New Zealand), DCANZ, and the research of Forages for Reduced Nitrate Leaching funded by MBIE and DairyNZ is gratefully acknowledged. We would like to thank Trevor Hendry, Roger Atkinson, Nigel Beale and Manjula Premaratne for technical support.
- Di HJ, Cameron KC (2002a) The use of a nitrification inhibitor, dicyandiamide (DCD), to reduce nitrate leaching and nitrous oxide emissions in a simulated grazed and irrigated grassland. Soil Use Manage 18:395–403Google Scholar
- Di HJ, Cameron KC (2002b) Nitrate leaching in temperate agroecosystems: sources, factors and mitigating strategies. Nutr Cycl Agroecosys 46:237–256Google Scholar
- Edwards GR, de Ruiter JM, Dalley DE, Pinxterhuis JB, Cameron KC, Bryant RH, Di HJ, Malcolm BJ, Chapman DF (2014a) Dry matter intake, body condition score change and urine nitrogen concentration of dairy cows grazing fodder beet, kale and kale-oat winter systems in winter. Proc NZ Grassland Assoc 76:81–88Google Scholar
- Edwards GR, de Ruiter JM, Dalley DE, Pinxterhuis JB, Cameron KC, Bryant RH, Di HJ, Malcolm BJ, Chapman DF (2014b) Urinary nitrogen concentration of cows grazing fodder beet, kale and kale-oat forage systems in winter. Aust Dairy Sci Symp Waikato, New Zealand, Nov 19–21(2014):144–147Google Scholar
- Edwards GR, Bryant R, Smith N, Hague H, Taylor S, Ferris A, Farrell L (2015) Milk production and urination behaviour of dairy cows grazing diverse and simple pastures. Proc NZ Soc An Prod 75:79–83Google Scholar
- FAO (2006) Livestock’s long shadow, environmental issues and options. Food and Agriculture Organization of the United Nations, RomeGoogle Scholar
- Ghani A, Ledgard S, Wyatt J, Catto W (2014) Agronomic assessment of gibberellic acid and cytokinin plant growth regulators with nitrogen fertiliser application for increasing dry matter production and reducing the environmental footprint. Proc NZ Grassland Assoc 76:177–182Google Scholar
- Jarvis SC, Scholefield D, Pain B (1995) Nitrogen cycling in grazing systems. In: Bacon PE (ed) Nitrogen fertilization in the environment. Marcel Dekker, New York, pp 381–419Google Scholar
- MFE (2015) New Zealand's greenhouse gas inventory 1990–2013. Ministry for the Environment, WellingtonGoogle Scholar
- Selbie DR, Buckthought LE, Shepherd MA (2014a) The challenge of the urine patch for managing nitrogen in grazed pasture systems. Adv Agron 129:229–292Google Scholar
- Selbie DR, Cameron KC, Di HJ, Moir JL, Lanigan G, Richards KG (2014b) The effect of urinary nitrogen loading rate and dicyandiamide nitrification inhibitor on nitrous oxide emissions from a temperate grassland soil. J Agric Sci Cam 152:S159–S171Google Scholar
- Soil Survey Staff (1998) Keys to soil taxonomy. 8th edition. Department of Agriculture, Washington DC, United States, US Government Print OfficeGoogle Scholar
- van Rossum MH, Bryant RH, Edwards GR (2013) Response of simple grass-white clover and multi-species pastures to gibberellic acid or nitrogen fertiliser in autumn. Proc NZ Grassland Assoc 75:145–150Google Scholar