The Nitrogen Dynamics of Newly Developed Lignite-Based Controlled-Release Fertilisers in the Soil-Plant Cycle.

The effect of newly developed controlled-release fertilisers (CRFs); Epox5 and Ver-1 and two levels of Fe 2+ applications (478 and 239 kg-FeSO 4 ha -1 ) on controlling nitrogen (N) losses, were tested on ryegrass, in a climate-controlled lysimeter system. The Epox5 and Ver-1 effectively decreased the total N losses by 37 and 47%, respectively, compared to urea. Nitrous oxide (N 2 O) emissions by Ver-1 were comparable to urea. However, Epox5 showed significantly higher ( p < 0.05) N 2 O emissions (0.5 kg-N ha -1 ), compared to other treatments, possibly due to the lock-off nitrogen in Epox5. The application of Fe 2+ did not show a significant effect in controlling the N leaching loss and N 2 O emission. Therefore, a dissimilatory nitrate reduction and chemodenitrification pathways were not pronounced in this study. The total dry matter yield, N accumulation, N use efficiency and soil residual N were not significantly different among any N treatments. Nevertheless, the N accumulation of CRFs was lower in the first month, possibly due to the slow release of urea. The total root biomass was significantly ( p < 0.05) lower for Epox5 (35%), compared to urea. The hierarchical clustering of all treatments revealed that Ver-1 outperformed other treatments, followed by Epox5. Further studies are merited to identify the potential of Fe 2+ as a controlling agent for N losses.