Study on the losing of ammonia volatilization and its influencing factors on the protected vegetable fields' soil

Ammonia volatilization is largely due to the excessive input of organic and inorganic nitrogen. Characteristics of ammonia volatilization under different fertilization measures, such as conventional fertilization (CON), conventional fertilization added with wheat straws (CNC), recommend fertilization (REF), and fertilization of organic manure only (OM), was studied by means of intermittent ventilation chamber in the protected vegetable field. Results show that ammonia volatilization is significantly decreased by reducing nitrogen fertilizer and returning the wheat straw to field. Throughout the whole monitoring period, the amount of ammonia volatilization for all of treatments is generally quite low. The nitrogen volatilization under conventional fertilization was the highest and account for 0.73% of total nitrogen application. More than 70% of ammonia volatilization is originated from chemical nitrogen fertilizer. The order of ammonia volatilization under different treatments is as follows: CON>CNC>REF>OM. During the monitoring period, the tendency of topsoil (0-1 cm) pH is decreased first and then increased. The biggest dropping range of pH (about 0.5 units) was observed in the CON treatment. Both of the surface soil's (0-1 cm) pH value and content of NH+4-N are positively correlated with ammonia volatilization rate (P< 0.05).