On 6/8/06 6:50 PM, "Noel Pattinson" <noel@netspace.net.au> wrote:
> I am puzzled as to why the ryegrass in my district is so much slower to
> reach 3 leaves than elsewhere.
> Noel Pattinson
> Greenacres
> Willung
> Gippsland
Noel, you could have high aluminium (Al) and/or low molybdenum (Mo) levels.
Mo is seldom low in New Zealand, but in central NSW applying Sodium
Molybdate at one kg/ha has greened up the whole farm. MEASURE Al and Mo in
pastures before applying any because too much is just as bad.
If the pasture level is below 0.5 ppm applying Sodium Molybdate at 1 kg/ha
can help.
Symptoms of low Mo include weak clovers with poor nodulation. In animals -
copper toxicity, low iron uptake and nitrate toxicity.
Where Al is high and Mo low, lime has a greater effect on increasing pasture
and animal production than Mo, so Mo should not be applied if Al is high or
if pH or calcium are low. Mo should not be used until adequate lime has been
applied.
Several farmers who have been wrongly advised to apply Mo and then had to
apply lime to correct the pH and calcium levels ended up with toxic pasture
Mo levels of over 10 ppm. Once up it is very, very difficult to reduce.
Adequate copper and sulphur help.
I¹ve updated the following from a book I¹m writing. Comments on it are
welcome.
Reasons for slow ryegrass growth
All times of year -
€ Low (< 5%) organic matter levels in soils that can be a reason for
ryegrass dying out.
€ Nitrogen levels too low because of clover deficiencies and/or leaching
from excess rain. See chapter on Pastures > Legumes.
€ Tight soils - lack of earthworms.
€ Pugging - even two or three months prior, depending on the severity.
€ Grazing too short and/or too many times. Ryegrasses tiller from the stems,
not the base so grazing short reduces tillers.
€ High aluminium (Al) levels. Al stops ryegrass (in particular) roots going
down so it grows less and is pulled out by cattle more easily. Velvet grass
(Yorkshire Fog) is not affected by Al. High Al (> 100 ppm in pasture) can be
a cause of perennial ryegrass pulling out as can high potassium (> 3.5%).
€ Lack of Ca and P both of which make aluminium less available.
Pasture analyses levels should be close to these below which are based on a
balance of pasture and animal requirements in 75% ryegrass & 25% white
clover. See Pasture Analyses spreadsheet for levels of other grasses.
Nitrogen N 4.50% Too high for animals, but necessary for optimum
pasture growth.
Phosphorus P 0.45%
Potassium K 2.80% Too high for animals, but necessary for optimum
pasture growth.
Sulphur S 0.40%
Calcium Ca 0.80%
Magnesium Mg 0.24% or higher for animals - expensive to keep there
except in high Mg soils.
Sodium Na 0.20% or higher for animals, but is expensive and hard to
keep up except near the coast. Feed salt in water or with grain.
ppm
Iron Fe 150
Manganese Mn 50
Zinc Zn 45
Copper Cu 13 Lower for sheep, but higher for cattle which may need
supplementing.
Boron B 22
Molybdenum Mo 1.5
Cobalt Co 0.13
Selenium Se 0.2 Should be higher, but hard to keep up. Feed in water
or with grain.
Aluminium Al <100
Iodine I 0.5 Expensive to achieve and leaches. Better to feed in
a soluble mineral mix in the drinking water through a dispenser.
See the chapters on Minerals for more details on each.
Best wishes,
Vaughan Jones
Hamilton
Waikato
New Zealand
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