Controlled-Release Urea Commingled with Rice Seeds Reduced Emission of Ammonia and Nitrous Oxide in Rice Paddy Soil

2 O) emission and enhanced nitrogen (N) fertilizer use efficiency have been investigated with different N fertilizer management and application methods for irrigated rice production. Few studies have examined NH 3 and N 2 O emissions from rice paddy soil when commingling controlled release urea with rice seeds. The objective of this study was to assess NH 3 volatilization and N 2 O emission from a novel controlled-release urea formulation (CRU-180) when commingled at the full application rate with seeds in a single application during the preparation of plant plugs at the nursery stage. The experiment was conducted as a factorial design with two fertilizer sources (conventional urea and CRU-180), four rates (0, 100, 200, and 300 kg N ha -1 ), and three replicates. The entire amount of CRU-180 was incorporated into each plug with germinated seed. The conventional urea was split into four applications based on the standard practice for fertilizer application. The CRU-180 treatments reduced the NH 4 + and NO 3 concentration in the paddy flood water and paddy soil solution as compared with the conventional urea treatments. The percentage of applied N fertilizer emitted as NH 3 volatilization and N 2 O emission in the CRU-180 treatments was only about 10% of that from the conventional urea treatments at the same N application rate. The application of CRU-180 with seeds offers a novel N fertilizer management technique, a method to reduce environmental impacts associated with rice production and the cost of rice production.