The effect of the nitrification inhibitor dicyandiamide (DCD) on herbage production when applied at different times and rates in the autumn and winter

Abstract

The high rate of urine excreted during animal grazing in late autumn provides a source of nitrogen (N) to the growing sward and also provides the potential for losses of N over the winter months. This study was established to evaluate the potential of applying a nitrification inhibitor, dicyandiamide (DCD), to urine patches to increase N use efficiency in grassland. Four simulated grazing plot experiments were undertaken across two experimental sites, one a free-draining acid brown earth (Experiments 1 and 3) and the other a moderate to heavy brown earth soil (Experiments 2 and 4). Experiments 1 and 2 received no fertiliser N application, and Experiments 3 and 4 received a split application of 350 kg N fertiliser ha −1 year −1. The effect of applying the nitrification inhibitor dicyandiamide (DCD) at 5 or 10 kg DCD ha −1 in autumn and winter to plots receiving synthetic urine or zero urine on spring and annual herbage production was examined in all experiments. The application of DCD did not increase spring herbage production in any of the experiments. Over the two years, the application of 5 or 10 kg DCD ha −1 increased annual herbage production in Experiment 1 when applied to October and November deposited urine patches. Urine application increased herbage production in spring and annually in Experiments 1 and 2, and increased herbage crude protein content and herbage N uptake in all experiments. The application of urine increased soil ammonium and TON content in the 0-100 mm horizon at both sites. The application of 10 kg DCD ha −1 reduced surplus N in Experiment 1 when applied to October and November deposited urine. Overall the effects of DCD on herbage production, surplus N and other parameters in this study were not consistent.

A 2-yr field assessment of the effects of chemical and biological nitrification inhibitors on nitrous oxide emissions and nitrogen use efficiency in an intensively managed vegetable cropping system

“…However, some previous studies have shown a shorter longevity and lower mobility of DCD compared with other NIs (Zerulla et al, 2001). In addition, The extent to which NIs inhibit N 2 O emissions and NO 3 À leaching is also primarily dependent on factors such as the application rate, time and method of NIs application (Barth et al, 2008;Verma et al, 2008;Zaman and Nguyen, 2012;O'Connor et al, 2012); field management practices (irrigation type, geometry and application method of NH 4 + -based fertilizers, Sanz-Cobena et al, 2012); climate (precipitation and temperature, Shepherd et al, 2012); and soil properties (moisture, pH, texture, organic carbon and mineral N, Barth et al, 2001;Shepherd et al, 2012). However, further research is required to verify this hypothesis.…”

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

“…Other studies have found a significant increase in pasture yield when DCD is applied in some seasons but not in others (e.g. Menneer et al 2008;O'Connor et al 2012;Zaman & Nguyen 2012), whereas some studies (e.g. Cookson & Cornforth 2002;Monaghan et al 2009) found no effect of DCD on pasture growth.…”

The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N<sub>2</sub>O emissions from an intensively managed vegetable field in southeastern China

“…Possible explanations for higher crop yields obtained with NH + 4 -containing fertilizers supplemented with nitrapyrin (Fig. 3) include the reduction of N losses by leaching and volatilization and the improved bioavailability of N and N uptake of the crops (O'Connor et al, 2012) in the vegetable soil. Ma et al (2013) reported that two types of NIs (nitrapyrin and DCD) increased average wheat yield by 9.7 % under conventional and no-till practices during the winter wheat-growing season.…”