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Combining restricted grazing and nitrification inhibitors to reduce nitrogen leaching on New Zealand dairy farms

journal contribution
posted on 2023-05-04, 10:13 authored by Alvaro RomeraAlvaro Romera, Rogerio Chicota, Pierre Beukes, Pablo Gregorini, Val SnowVal Snow, Iris Vogeler
Intensification of pastoral dairy systems often means more nitrogen (N) leaching. A number of mitigation strategies have been proposed to reduce or reverse this trend. The main strategies focus on reducing the urinary N load onto pastures or reducing the rate of nitrification once the urine has been deposited. Restricted grazing is an example of the former and the use of nitrification inhibitors an example of the latter. A relevant concern is the cost effectiveness of these strategies, independently and jointly. To address this concern, we employed a modeling approach to estimate N leaching with and without the use of these mitigation options from a typical grazing dairy farm in New Zealand. Three restricted grazing options were modeled with and without a nitrification inhibitor (dicyandiamide, DCD) and the results were compared with a baseline farm (no restricted grazing, no inhibitor). Applying DCD twice a year, closely following the cows after an autumn and winter grazing round, has the potential to reduce annualized and farm-scale N leaching by ∼12%, whereas restricted grazing had leaching reductions ranging from 23 to 32%, depending on the timing of restricted grazing. Combining the two strategies resulted in leaching reductions of 31 to 40%. The abatement cost per kilogram of N leaching reduction was NZ$50 with DCD, NZ$32 to 37 for restricted grazing, and NZ$40 to 46 when the two were combined. For the range analyzed, all treatments indicated similar cost per percentage unit of mitigated N leaching, demonstrating that restricted grazing and nitrification inhibitors can be effective when used concurrently.


Rights statement

Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.


  • English

Does this contain Māori information or data?

  • No



Journal title

Journal of Environmental Quality




Romera, A. J., Chicota, R., Beukes, P. C., Gregorini, P., Snow, V. O., & Vogeler, I. (2017). Combining restricted grazing and nitrification inhibitors to reduce nitrogen leaching on New Zealand dairy farms. Journal of Environmental Quality, 46(11), 72–79. doi:10.2134/jeq2016.08.0325

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