1
Low-Soil Moisture Dramatically Drives Up Ammonia
Volatilization Guodong Liu1, Y.C. Li1 and A. K.
Alva2 1University of Florida-TREC, 18905 SW 280
St, Homestead, FL 33031, USA 2USDA-ARS 24106 N
Bunn Rd., Prosser, WA 93305, USA Phone
[phone]x355 FAX [phone] E-mail
gliu_at_ifas.ufl.edu
  ABSTRACT  
  RESULTS  
Ammonia volatilization is an important mechanism
of nitrogen (N) loss from soils which is
dependent on several soil and management factors.
This research was conducted with Biscayne Marl
Soil and Krome Gravelly Loam from Florida and
Quincy Fine Sand and Warden Silt Loam from
Washington to determine ammonia volatilization at
various temperatures and soil water regimes using
either KNO3, NH4NO3, (NH4)2SO4 or urea applied to
the soil at 75 kg N ha-1 rate. Soil water regime
was maintained at either 20 or 80 of field
capacity (FC), and incubated at either 11, 20 or
29 oC which represent the minimum, average and
maximum temperatures, respectively, during potato
growing season in Washington. Results indicated
that the ammonia volatilization rate at 20 FC
soil water regime was 2- to 3-fold greater than
that at 80 FC. The cumulative volatilization
loss over 28 days accounted for 0.21 loss of N
applied as NH4NO3. This loss increased to 25.7
for (NH4)2SO4. Results of this study demonstrate
that NH3 volatilization was significantly
accelerated at low soil water regimes. Thus,
maintaining near optimum soil water regime is
important to minimize volatilization loss of N
and to improve N uptake efficiency in addition to
its direct effects on plant growth and nutrient
uptake.
1. Dynamical rates of NH3 emission
3. Effects of soil pH and incubation
temperature on NH3 emission
 OBJECTIVES 

1. To estimate NH3 volatilization rates from soil
   for potato production
2. To quantify the effects of soil moisture and
   temperature on NH3 emission
3. To identify relationships among soil types, soil
   moisture levels and incubation temperatures on
   NH3 volatilization

 MATERIALS AND METHODS 
1. Soils tested
Figure 3. Higher soil pH quickly drives up
ammonia volatilization from different N sources
at 20 FC much more dramatically than that at 80
FC at either 11, 20 and 29 oC.
Figure 1. Dynamical rates of ammonia
volatilization from different N sources applied
to four soils incubated at 20 oC at either 20 or
80 FC soil water regimes. Vertical lines at each
data point represent the standard error of the
mean.
  CONCLUSIONS  
2. Cumulative NH3 emission
Results of this study revealed that N
volatilization loss was significantly influenced
by the effects of soil type, soil water content,
fertilizer, and temperature treatments. Across
all N sources, and soils used in this study
volatilization loss was greater at lower soil
water regime than that at near field capacity
soil water regime. Among the N source, NH3
volatilization was greater from ammonium sulfate
or urea as compared to that from either ammonium
nitrate or potassium nitrate source. Furthermore,
NH3 volatilization was greater from high pH soils
sampled from Florida as compared to that from the
slightly lower pH soil sampled from Washington.
This difference could also be influenced by other
soil properties including soil texture and
biological activities.
  ACKNOWLEDGEMENTS  
2. Incubation and sampling
This research was supported by the Florida
Agricultural Experiment Station and a grant from
USDA-ARS.
 REFERENCES 

1. Alpkem Corparation. 1989. RFA methodology for
   ammonia nitrogen. A303-S020. Alpkem Corporation,
   Clackamas, Oregon. P. 7
2. Cabrera ML, SC Tyson, TR Kelley, OC Pancorbo, WC
   Merka and SA Thompson. 1994. Soil Sci. Soc. Am.
   J. 58 367-372
3. FAO, 2001, Global estimates of gaseous emissions
   of NH3, NO and N2O from agricultural land.
4. Fenn, LB and LR Hossner. 1985. IN Advances in
   Soil Sciences (ed. BA Stewart). 1985.
   Springer-Verlag, New York, Berlin, Heidelberg,
   Tokyo. Pp 123-169 .
5. He, ZL, A.K. Alva, D.V. Calvert and D.J. Banks.
   1999. Soil Sci. 164 750-758

pH 7.27
pH 6.65
pH 6.46
pH 7.69
3. Ammonia analysis In AutoAlanyzer III
according to EPA, Method 350.1 (EPA, 1993).
Figure 2. Cumulative ammonia volatilization from
different N sources applied to four soils
incubated at 20 oC at either 20 or 80 FC soil
water regimes.