Field studies assessing the effect of dicyandiamide (DCD) on N transformations, pasture yields, N2O emissions and N-leaching in the Manawatu region

• Published in: New Zealand journal of agricultural research 2014-10, Vol.57 (4), p.271-293
• Main Authors: Kim, D-G, Giltrap, DL, Saggar, S, Hanly, JA
• Format: Article
• Language: English
• Subjects: autumn; dairy farming; DCD; dicyandiamide; drainage; drainage water; Emissions; field experimentation; greenhouse gas emissions; half life; Leaching; nitrates; nitrification; nitrification inhibitor; nitrification inhibitors; Nitrogen; nitrogen leaching; Nitrous oxide; nitrous oxide emission; pasture yield; pastures; soil; urine; winter; yields
• ISSN: 1175-8775; 0028-8233; 1175-8775
• DOI: 10.1080/00288233.2013.855244

Nitrification inhibitors (NI) allow retention of soil nitrogen (N) in the ammonium (NH ₄⁺) form for longer periods. Therefore, they can potentially increase pasture yields by decreasing N losses via nitrous oxide (N ₂O) emissions and nitrate (NO ₃⁻) leaching. Multiple field experiments were conducted over 3 years at a Massey University dairy farm in the Manawatu region to determine the effect of the NI dicyandiamide (DCD) on soil N transformations, N ₂O emissions, pasture yields and NO ₃⁻ leaching. Over the study period, DCD applied in autumn and winter had a half-life of 12–17 days and persisted in the soils between 42 and 84 days. Application of DCD inhibited the nitrification process, resulting in lower N ₂O emissions (54%–78% from urine patches). N ₂O emissions were further reduced using two applications of DCD, but more than two applications had no additional effect. Although the influence of DCD on pasture accumulation or NO ₃⁻ leaching was not consistent, three applications of DCD increased pasture accumulation by 9% and reduced NO ₃⁻ leaching by 22% in one of 2 years of the grazed drainage trial. However, the latter was largely influenced by lower drainage water volumes, rather than lower NO ₃⁻ concentrations.