Abstract: With venting method, this paper determined in situ the ammonia (NH3) volatilization from the soils of typical meadow Calamagrostis angustifolia wetland and marsh meadow C. angustifolia wetland in Sanjiang Plain, and analyzed its main affecting factors. The results showed that the change trends of the NH₃ volatilization rates of these two typical C. angustifolia wetland soils were basically the same, with two peaks and a valley before the middle ten days of July, and as a whole, strictly monotony downtrend afterwards. The NH₃ volatilization rate of marsh meadow C. angustifolia wetland was relatively high, with an average value being 1.35±0.53 folds of typical meadow C. angustifolia wetland. The change trends of cumulative NH₃ volatilization amounts were also basically the same, i.e., before the middle ten days of July, they increased rapidly and the values were relative proximity, but afterwards, the values increased slowly and marsh meadow C. angustifolia wetland had a much higher value. In growing season, the total NH₃ volatilization amount of typical meadow C. angustifolia wetland and marsh meadow C. angustifolia wetland soils was 6.35 and 6.87 kg N·hm^-2, respectively. The analysis of affecting factors indicated that the storage of soil nitrogenous compounds was not the limiting factor affecting the process of NH3 volatilization, while atmospheric temperature and its caused temperature fluctuation were the important factors affecting the changes of NH₃ volatilization rate. Precipitation and the fluctuation and evaporation of soil moisture were the important inducers of the partial fluctuation of NH₃ volatilization rate, soil pH and texture were the main factors inducing lower NH₃ volatilization rate, and the integrative action of all the factors induced the changes and differences of NH₃ volatilization　rates and NH₃ volatilization amounts of the two typical C. angustifolia wetland soils.

Key words: Wheat, Wet injury, Nutrition regulation