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Forage & Nutrition
Guide 2018
mineral soils is 6.3 and on organic (peat) soils is 5.5. On
grassland soils with high molybdenum (Mo) levels, increasing
soil pH above 6.2 can lead to increased Mo levels in the
herbage. High intakes of Mo in ruminant animals can lead
to an increased risk of copper deficiency. It is therefore
recommended to maintain soil pH at 6.2 on these soils or
consider supplementing animals with copper. Apply lime
based on the soil test report. Where lime recommendations
exceed 7.5 t/ha, it is best to split the application rate and
apply up to 7.5 t/ha initially and the remainder in year
three. Lime can be applied at any time of the year, however,
mid-summer and autumn are ideal as soils are still firm
and there are increased spreading opportunities following
silage harvesting and grazing. Ground limestone is the
most cost effective source of lime. It will start to work once
it is applied and washed into the soil. Use magnesium (Mg)
limestone where soil Mg levels are low to replenish it in the
soil. Granulated limes are a finely ground limestone (<0.1mm)
hastening the reaction with soil acidity to increase soil pH in
the shorter term. Recent research shows that these products
are more suitable for maintaining soil pH (i.e. where the initial
soil pH is close to the target ie. 6). Maintaining soil pH will
result in increased release of soil N from organic matter up to
a value of 80/ha per year."
LITTLE AND OFTEN ON HEAVY SOILS
The advice on some heavier and organic soils is that it is best
to apply a reduced rate of lime on a more regular basis to
control soil acidity rather than as one large application as this
avoids 'softening' the soil. It is also recommended to leave at
least three months between liming and the application of urea
or slurry to reduce the risk of N loss through volatilisation. To
overcome this, apply urea/slurry first and apply lime 10 days
later.
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