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MARCH 2018
Tillage Focus
MARCH 2018
Tillage Focus
or breakdown of organically bound S is dependent on a soil's
biological activity and, therefore, the health of a soil will have a
major impact on the supply of plant-available S. Because of the
leachable nature of available S or sulphate in the soil, the build-
up of S through this route is not possible. Up to 50kg of S/ha
can be leached from intensive grassland systems. The rate of S
mineralisation from organic matter is very slow in spring, and this
supply alone is not enough to meet the demands of the grass crop
on intensively grazed farms or for first-cut silage. Work carried out
by the Agri-Food and Biosciences Institute (AFBI) in Northern
Ireland over 10 years ago, where they surveyed the S status of first-
cut and second-cut silages on 67 dairy farms in Northern Ireland,
showed that 33 per cent and 58 per cent of first-cut silage fields on
heavy textured and moderately textured soil types, respectively,
were considered S-deficient. There was a reduction in S deficiency
rates on second cuts, with 8 per cent and 39 per cent rates of
deficiency on the heavy textured and moderately textured soil
types, respectively. This indicates that the supply of mineralised
S from organic matter is very low in spring and will only supply
appreciable amounts of available S for plant uptake from June
onwards. It is highly likely that if this survey was undertaken by
AFBI now, the deficiency rates would be higher.
We can test our soils and grass for S, with grass being the most
accurate indicator of soil S supply. We should not look at the
S levels alone but look at the ratio of N:S in your grass analysis
report. The S levels in grass should be at or above 0.2 per cent of
dry matter (DM) and the N:S ratio should be less than 14:1.
Will there be enough S in slurry to meet grass requirements? The
answer is no, because the S in slurry and dung is organically bound
and will require a period of time before this will be mineralised
into a plant available form, which is likely to be in the latter half of
the growing season. This is a valuable source of S but should not
be counted on to meet grass demand from early spring to June.
The S content of cattle slurry varies considerably and Teagasc has
estimated it to be 0.3kg/t.
We should look to apply 20kg/ha of chemical S over the course
of the grazing season depending on your chemical N use and we
would like to supply the greater proportion of this 20kg in the first
half of the grazing season with S applied with each N split. Applying
your entire S requirement in one or two applications is not advised
due to the leachable nature of sulphate in the soil and when
sulphate leaches from the soil it also takes valuable nutrients with
it such as calcium, magnesium and potassium. High application
rates of AS and ASN have a greater acidification effect on soil. This
effect is greatest on lighter textured soils or soils with low buffering
For silage, it is recommended to apply 20kg/ha of S prior to closing
on first-cut silage swards. For the second cut an application rate of
15kg/ha is sufficient, as mineralised S from soil organic matter and
slurry will contribute to the overall supply of plant-available S.
When choosing a fertiliser product, take into account if it
contains S and attribute a value to this as this is regularly
overlooked because fertiliser is often valued solely on its N
Cavello Apollo Stainless
Steel Twin Disc Fertilizer
18 meter spreading width.
Basic model 12cwt capacity
with extensions available to
increase capacity to either
19cwt or 26cwt, Stainless
Steel Disc, vanes and filtering
pans, Loading height from
0.94 metres for basic model
to 1.24 metres for 26cwt
Cavallo Zeus Stainless Steel
Fertilizer Spreader
Basic model 18cwt with
stainless steel extensions
available to increase capacity
to 1.5 tons or 2 tons,
Stainless steel spinning disc,
vanes and vibrating pans,
Filtering grids, PVC covers
are optional extras, Hydraulic
shut off on either side as
standard, Protection bars
Cavello Compact 590 Twin
Disc Fertilizer Spreader
Available in painted and
stainless steel versions, 14cwt
capacity in basic model
with extension available to
increase capacity to 18cwt,
Stainless steel spinning discs,
vanes and vibrating pans.
Cavallo 890PXT
16cwt Capacity Wagtail
spreader c/w Stainless Steel
Hopper, protection bar,
filtering grid and hydraulic
controlled opening/closing.
Hopper can be tilted for
ease of cleaning machine.
Stainless steel extension to
increase capacity to 24cwt
can be fitted at additional
Dublin Road, Cavan, Ireland
Tel: 00353 437 5900
Mob:00353 87 681 10 85
00353 87 2111540
Fax 00353 49 433 16 42