I believe that the K and S are much too high and here I would apply a lot
more reactive phosphate P, unless soils are alkaline.
If sulphate S in not used, Ca (agricultural lime) is applied regularly and
40 kg of agricultural salt/ha pa (except on coasts and high Na areas), K may
not be needed for years, saving a lot of money, bloat and perennial ryegrass
pulling (K makes grasses hard).
I first read about this from Dr Max Turnerıs work at Massey University in
Palmerston North, NZ, decades ago and then in Indian research 15 years ago.
Massey then repeated the trials twice with the same results.
The most important source of S for pastures is elemental sulphur (S). It is
not water soluble like the sulphuric acid (H2SO4) made sulphate sulphur in
single superphosphate, so is therefore not leached from the soil. Elemental
sulphur relies on acidity, moisture and soil bacteria which grazed pasture
soils usually have plenty of break it down before plants can use it.
Elemental sulphur doesn't leach, but must be finely ground - to less than
0.5 mm, or be in a small pelleted form which will dissolve, to be released
within a year, when more should be applied.
Researcher WMH Saunders of Massey University pointed out that savings on
many soil types by using good reactive phosphate with elemental sulphur
could amount to between $15 and $50 million a year, compared with using
superphosphate.
Note:
Elemental S can be dangerous so must be handled with care. Mixing it with
other items can cause dust and an explosion if more than 20% is elemental S.
Sulphate S must not be used because it leaches many items and lowers
selenium availability to animals. Elemental S should be used at about
between 10 and 20 depending on pasture levels.
Pastures are best fertilised with elemental sulphur rather than sulphate S
because elemental releases S gradually and doesnıt leach and take other
elements with it. In some cases deficiencies in pastures (yellowing of
clovers) can be seen six months after applying superphosphate (0-9-0-11)
because water-soluble sulphate S leaches. Elemental S should not be applied
if Superphosphate has been applied recently because the soil will already
have much more S than is necessary.
Information from the Massey University Fertilizer and Lime research showed
the loss of calcium, chlorine, magnesium, nitrogen, potassium, sodium and
sulphur after applying 450kg /ha of Superphosphate that has 50kg/ha of
sulphate sulphur. The nutrients were measured in field tiles.
Leaching of Nutrients by Sulphate S in kg/ha
1988 1989
Sulphate S Elemental S Sulphate S Elemental S
Element Paddock A Paddock B Paddock A Paddock B
Chlorine 117.8 92.8 76.3 71.9
Sulphur 17.0 3.4 9.4 3.5
Nitrogen 12.6 8.6 19.1 14.9
Calcium 52.5 35.2 40.8 30.7
Potassium 10.8 5.7 7.1 3.3
Magnesium 15.0 10.8 11.3 9.1
Sodium 64.5 50.8 31.9 31.1
Using good (not all AR good) reactive phosphate and elemental S saves money
and reduces pollution.
On 11/8/06 7:54 AM, "Frank Tyndall" <ftyndall@ozemail.com.au> wrote:
> Dear all,
> Can I do a little survey please?
> How much N P K S element per year are people applying?
> Or for the experts, how much should people be applying (assuming an
> average sort of soil fertility currently, and wanting to do, say, 12 plus
> tonne grass)?
> Like, I reckon: 300:60:120:40. Am I anywhere near the mark?
> Regards
> Frank Tyndall
>
Best wishes,
Vaughan Jones
Agricultural consultant
Hamilton
Waikato
New Zealand
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