M G. Mason

Publication Date


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DPIRD Collections

Grains and field crops


Ammonium nitrate is a source of nitrogen containing half

its nitrogen in the ammonium form and half in the nitrate form.

Some properties are set out in comparison with urea in the

following table.

Ammonium nitrate has an advantage over urea in that it can

be topdressed onto the surface of the soil and left uncovered

without a danger of loss of nitrogen to the atmosphere. When urea

is left uncovered on the surface of the soil losses of nitrogen occur

through volatilisation of ammonia during the hydrolysis of the urea.

Such losses with ammonium nitrate are only likely to occur on highly

calcareous soils. The loss from urea can be largely avoided if the

urea is covered with a layer of soil e.g. by topdressing in front of

the seeding tines or discs. Also there is not likely to be much

loss from the urea topdressed onto the soil surface if the application

is followed closely by heavy rain which will wash the urea into

the soil.

On the other hand freight will be a little higher for

ammonium nitrate because of its lower nitrogen content than urea.

Number of Pages



Western Australia, Fertiliser, Application rates, Ammonium Nitrate, Urea


Agronomy and Crop Sciences | Soil Science

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