1 Nitrate is mobile in the soil and rapidly
absorbed by plants. Ammonium has limited
mobility and is not at risk of leaching.
2 Soil microbes compete with plants for
nitrogen and immobilize part of it in
soil organic matter. The nitrogen in soil
organic matter is not lost, but it needs to
be mineralized before it can be taken up
by plants. Part of immobilized nitrogen is
mineralized during the growing season.
Part of it is mineralized later. Split nitrogen
application would ensure rapid uptake of
available nitrogen by plants and thus reduce
immobilization.
3 With good agricultural practice, only a very
small portion of applied fertilizer nitrogen
can be found in the residual nitrate pool upon
harvesting.
4 Manure contains nitrogen mainly as organic
compounds, building up soil organic matter.
This nitrogen is not immediately available.
5 Manure, especially slurry, also contains some
mineral nitrogen, mainly as ammonium.
The proportion of mineral nitrogen in manure
varies depending on its sources.
6 Mineralization of soil organic matter
contributes to soil nitrogen supply.
Mineralization rates are variable. For
example, mineralized nitrogen for grassland
can exceed 300 kg/ha. After harvest,
however, microbes find optimum conditions
in the humid and warm autumn soil.
Since there are no more plants to use the
nitrate produced, it is prone to leaching.
7 During the growth period, mineralized
nitrogen contributes to plant nitrogen uptake.
Determining soil nitrogen supply accurately by
sampling and use of precision farming tools
avoids over-fertilization and reduces leaching.
8 Autum and winter rainfall stocks up the
water table. Most of the residual nitrate is
leached in these two seasons. During spring
and summer there’s usually little rain, and
evaporation from the plough layer counteracts
leaching. Keeping the residual nitrate pool as
small as possible is the best strategy against
leaching.
Conclusion
Nitrogen can be applied as manure
or mineral fertilizer. Manure mainly
augments the soil organic matter pool,
which needs to be mineralized first before
plants can take it up.
Leaching occurs when un-used mineralized
nitrogen is washed out in ground water
during winter time.
Nitrogen from mineral fertilizer, especially
when applied as nitrate, is immediately
available for plants. Tailored and split
application of mineral fertilizer reduces the
residual nitrate pool after harvest and thus
prevents leaching.
AN
UAN
UREA
Yield or Environment ?
Let’s care for both !
Optimizing yields while preserving the environment
– this is the challenging claim of agriculture today.
Undesirable ecological impact from nitrogen fertilizer
is observed when nitrogen is lost into the environment.
Nitrate-based fertilizers are pure nutrients offering the
required precision, efficiency and reliability to keep such
losses at a minimum.
Nitrate-based fertilizers meet the agronomic and
ecological requirements of modern agriculture.
They are the natural choice for farmers who care for
both, yield and the environment.
YaraBela®
Yara’s nitrate-based fertilizer containing 50 % nitrate:
Manure
Mineral
Nitrogen
YaraBela®
EXTRAN® 33,5
Quality ammonium nitrate
with 33,5% N.
Soil Organic
Matter
Mineral
Nitrogen
NH4+ )
(NO3,
Organic
Nitrogen
Mineral
Nitrogen
YaraBela®
SULFAN®
Quality sulphur fertilizer with
optimum N/S ratio.
Universally applicable for all crops.
With 24% N and 6% soluble
sulphur.
YaraBela®
OPTIMAG® 24
The fertilizer for soils and crops
needing magnesium.
With 24% N, 6% soluble sulphur
and additional 8% soluble
magnesium (MgO).
Nitrogen Leaching
Yara International ASA
Bygdøy Allé 2,
P.O. Box 2464, Solli
N-0202 Oslo, Norway
www.yara.com