Fillery and Khimashia Ammonia Volatilisation Calculator
Fillery I R P and Khimashia N (2016) Procedure to estimate ammonia loss afer N fertiliser application to moist soil. Soil Research, 54, 1-10.
Fillery and Kamashita Ammonia Volatilisation calculator is a calculator  provides a simple and logical process whereby the extent of potential short term ammonia volatilsation loss from urea application can be explored. The output is in terms of a most likely  % N volatilised based on a range of important soil, water and application factors, and equations described in Fillery and Khimashias' 2016 Soil Research Journal paper  "Procedure to estimate ammonia loss after N fertiliser application to moist soil" .
General White cells  in the calculator with down arrows can be edited or changed. When cells are clicked  a drop down menu will appear. Select the closest value to best describe your situation. Should you wish to compare two different scenarios, enter relevant parameter selections in columns Scenario 1 and 2.
Soil pH Starting soil pH was found to have a relatively minor loss driver from urea as the ammonia  (and subsequent ammonium hydroxide) evolved  is generally sufficent to overcome soil buffering and create a pH around 9.5 in at the adsorption site and in the soil solution.  Future version will cater for ammonium sulfate in which case starting soil pH is and important driver of loss.
Clay content % Clay content is a key factor in adsorption as in this calculator it is used as a surrogate for cation exchange capacity (CEC). Ammonium  is highly water soluble and has high exchange affinity. It is strongly held and adsorbed in greater quantities in soils with higher CEC and water content reducing loss potential. Select a  soil clay % based on your knowledge of soils in your area or using infomation from apps such as SoilMapp.
Fertiliser product The original  research paper includes data for comparisons between urea, ammonium sulfate and UAN. Urea is the only product available at this time in this calculator.
Fertiliser rate Select N rate in kg/ha. Maximum rate is 200 kg/ha.
Soil texture/ rainfall Rainfall is a key factor that reduced urea content at the soil surface therby reducing N loss. The amount of rainfall needed to displace urea is dependant on clay content. This cell in combination with the" Days after application" describe the time till loss is minimised by either incorporation or loss rate is reduced by a lower urea concentration remaining. In this cell select the combination of soil texture group and rainfal quantity that best describes your situation.
Days after application Select the estimate number of days till a significant rainfall (selected in  Soil texture/ rainfall )event after the soil surface. first becomes moist
Crop stage Speed of air flow is a significant factor that modifies volatilisation loss. Lower airspeed occurs at the soil surface when a crop canopy is presen,t hence loss is reduced. Select appropriate crop stage if applying N in crop.
Fertiliser placement Volatilisation loss is geater where the soil fertiliser contact is minimal. Select the likely location of the product after application from the list of options.
% hung up in stubble Crop stubbles generally have high urease content and very little CEC hence are a location that has greater loss potential than soil. This factor was not described in the original research paper but has been included for use on the basis that all N in stubble will be lost in addition to soil losses. 
N cost ($/kg N) Select an N cost that is most recent. Inputting N cost will help in assessing the cost or savings potentially availabe from different application strategies.
Output Calculated emission factor (%) is the percentage of N loss via ammonia volatilisation calcated from the input paramenters and ther relationships described in the journal paper.
Estimated N  loss (kg/ha) is  the quantity of N loss calculated fron the emission factor and the application rate selected.
Estimated value of loss ($/ha) is the value of N loss based on the Estamate N loss and the N cost selected.
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1. I should not make significant decisions in reliance on the Fillery and Khimashia Volatilisation Calculator or information obtained from this application, but should consider the information along with other available information.
2. I accept all risk and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this site, this application, or any information from them, and
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Fillery and Khimashia Ammonia Volatilisation Calculator
  Scenario 1 Scenario 2  
Soil pH - soil pH is mostly overwhelmed by the alkalinity created by the ammonium created at the site of soil contact with urea hence starting soil pH is a minor factor in ammonia loss process. Soil pH is very a important modifier of loss from ammonium sulfate.
Soil pH (water)
Soil CEC and hence clay content is a key factor in ammonia volatilisation loss.
Higher clay soils provide more adsorption capacity for ammonia thereby reducing loss potential.
Soil clay content (%)
Ammonia volatilisation potential for UAN and ammonium sulfate to be added at a later date.
Fertiliser product
Maximum rate is 200 kg/ha of N
Fertiliser N rate (kg/ha)
Soil texture/ rainfall
Number of days after the soil initially becomes moist enough to promote urea granule slumping and before rainfall equal or more than the quanity indicated above or cultivation to 5 cm.
Days after application
Crop  stage
Fertiliser placement
% hung up in stubble
N cost ($/kg N)
Calculated Emission Factor  
Estimated N Loss (kg/ha)  
Estimated Value of N loss ($/ha)