AMMONIA VOLATILIZATION FROM LIQUID DAIRY CATTLE MANURE IN THE FIELD

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Abstract
The volatilization of ammonia from applied liquid dairy cattle manure was measured in the field during 6- to 7- day periods in early May of 4 yr. An "open" system involving an aerodynamic diffusion method was employed for these measurements. Ammonia flux followed a diurnal pattern with maxima occurring shortly after midday and minima occurring during the early morning hours. The magnitude of daily flux values tended to decrease with time. However, both temperature and rainfall influenced the magnitude of ammonia flux. Generally, ammonia flux values increased with temperature but were suppressed by rainfall. Over periods of 6 or 7 days following the time of manure application, between 24 and 33% of the ammoniacal N applied in the manure was lost by volatilization. Samples of manure taken immediately following application and 5 days later showed a decrease in ammoniacal N concentration during this period. Although some ammonium moved into the 0- to 2- cm soil layer, immediately following application, most appeared to remain in the manure layer in spite of rainfalls which occurred during the experimental periods. Five days following manure application, the relatively large quantities of ammoniacal N remaining in the manure layer were subject to potential volatilization.