Nutrient Management Research Database

The consumption of synthetic nitrogen fertilizer in agriculture has increased over the past several decades and will continue to increase to meet the food and fibre demands of the growing global population, which will no doubt result in the release of additional N₂O into the atmosphere. A wise use of synthetic fertilizer N is important to mitigate N₂O emissions. Outdoor pot experiments during the winter wheat (Triticum aestivum L.) growing season and field experiments during the maize (Zea mays L.) growing seasons were undertaken from 2006 to 2008 at Nanjing in eastern China to evaluate the potential of a range of typical slow-release fertilizers to mitigate N₂O emissions. Five slow-release N fertilizers, including physically altered (Ca-Mg-P-coated urea, polymer-coated urea and sulfur-coated urea), chemically altered (urea formaldehyde) and biochemically inhibited (urea with dicyandiamide and hydroquinone) nitrogen were applied in this experiment. In comparison with commercial urea, the urea formaldehyde treatment reduced N₂O emissions by ∼42% for the wheat growing season and 15-26% for the maize growing season, and the urea with dicyandiamide and hydroquinone treatment reduced N₂O emissions by 33-63% for the maize growing season. However, the treatments with Ca-Mg-P-coated urea, polymer-coated urea and sulfur-coated urea generally enhanced N₂O emissions in comparison to the emissions of the urea-treated fertilizer, especially when precipitation followed application. We conclude that the application of chemically altered or biochemically inhibited nitrogen fertilizers would have great potential to mitigate N₂O emissions, but the use of physically altered nitrogen fertilizers may have the opposite effect than desired.

Two experiments were performed, an outdoor pot grown wheat experiment and true field experiment in a corn cropping system. Nitrous oxide emissions were measured following the application of five types of slow release fertilizers. The fertilizers investigated were Ca-Mg-P coated urea, polymer-coated urea, sulfur-coated urea, urea formaldehyde, and urea with dycyandiamide (DCD) and hydroquinone (HQ).

Wheat Experiment

Wheat plants grown in pots were fertilized with all 5 fertilizers tested at a rate of 220 lbs N/ac along with 220 lbs P2O5 and K2O per acre. All fertilizers were broadcast applied in a single event, except for urea which was split into 3 applications. Nitrous oxide were measured from from sowing to harvest for a single season.

Corn Experiment

Corn plants were fertilized with 270 lbs N/acre of all 5 fertilizers along with 270 lbs P2O5 and K2O per acre. Urea applications were split between 108 lbs N/ac at plant emergence and the remainder during tasseling. Other fertilizers were applied entirely at plant emergence. Nitrous oxide were measured from from sowing to harvest for a single season.

Urea formaldehyde reduced nitrous oxide emissions bt 42% for wheat and 15-26% for corn.

Urea with DCD and HQ reduced emissions by 33-63% in the corn system.

The other fertilizers tested increased N2O emissions are compared to urea treatments.