DYNAMICS OF AMMONIA VOLATILIZATION FROM TURKEY MANURE AND UREA APPLIED TO SOIL

Field measurements of NH3 VolatiliZation from both surface-applied and incorporated turkey (Meleagris gallopavo) manure (20 g of N m-2, which compares with 16 Mg of manure ha-1) and urea (20 g of N m-2) were made using the forced-draft technique for a 6-d period in early June 1991. The soil (temperature and water potential) and atmospheric parameters (relative humidity, wind speed, and air temperature) affecting NH3 volatilization rate were also measured. Ammonia losses for manure and urea followed a diurnal pattern; maxima occurred shortly after midday (between 1200 and 1800 h), when soil temperature was nearing maximum and wind speed was highest, and minims occurred during midnight to early morning hours (between 2400 and 0600 h), when the soil temperature was lowest and relative humidity was highest. Significant positive correlations between rates of NH3 volatilization and soil temperature, atmospheric temperature, and wind speed were observed. Relative humidity was generally negatively correlated with NH3 volatilization. Ammonia volatilization from the surface-applied manure was highest immediately after application and gradually decreased with time, whereas ammonia volatilization from surface-applied urea did not start until Day 2 and reached a maximum on Day 6. The total NH3 loss from incorporated manure was 23 times lower than that from surface-applied manure (0.5 vs. 11.5 kg of N ha-1), whereas NH3 loss from urea was eight times lower when incorporated (0.2 vs. 1.5 kg N ha-1) during a 6-d period. Total N loss (6 d) from surface-applied urea was eight times lower than an equivalent amount of inorganic N in turkey manure (1.5 vs. 11.5 kg of N ha-1). Ammonia volatilization from turkey manure and urea was found to be influenced by a combination of environmental factors and the method of application.