Emissions of NO and NH(3) from a Typical Vegetable-Land Soil after the Application of Chemical N Fertilizers in the Pearl River Delta

Cropland soil is an important source of atmospheric nitric oxide (NO) and ammonia (NH(3)). Chinese croplands are characterized by intensive management, but limited information is available with regard to NO emissions from croplands in China and NH(3) emissions in south China. In this study, a mesocosm experiment was conducted to measure NO and NH(3) emissions from a typical vegetable-land soil in the Pearl River Delta following the applications of 150 kg N ha(−1) as urea, ammonium nitrate (AN) and ammonium bicarbonate (ABC), respectively. Over the sampling period after fertilization (72 days for NO and 39 days for NH(3)), mean NO fluxes (± standard error of three replicates) in the control and urea, AN and ABC fertilized mesocosms were 10.9±0.9, 73.1±2.9, 63.9±1.8 and 66.0±4.0 ng N m(−2) s(−1), respectively; mean NH(3) fluxes were 8.9±0.2, 493.6±4.4, 144.8±0.1 and 684.7±8.4 ng N m(−2) s(−1), respectively. The fertilizer-induced NO emission factors for urea, AN and ABC were 2.6±0.1%, 2.2±0.1% and 2.3±0.2%, respectively. The fertilizer-induced NH(3) emission factors for the three fertilizers were 10.9±0.2%, 3.1±0.1% and 15.2±0.4%, respectively. From the perspective of air quality protection, it would be better to increase the proportion of AN application due to its lower emission factors for both NO and NH(3).