graze-l April 2006: [SPAM] - Re: [SPAM] - RE: [SPAM] -
Re: [Graze-l] increased need for minerals in spring? - Email found in subject -
Email found in subject - Email found in subject
On 23/4/06 09:39, "AgriSolutions" <seagrow@dcsi.net.au> wrote:
> Hmmmmmmmm.......so why is N applied so prolifically across the season when
> it is known that there is less mineral uptake at times of faster growth? Is
> it not the minerals for which the cows eat the grass?
>
> Best regards,
>
> Gerhard
Reasons -
1. In New Zealand, because a fertiliser company owns the urea manufaturing
plant and sponsors research which is then promoted. Our government
contributes little to actual research now, whereas pre our stupid
Rogernomics (extreme USA capitalism that USA gave up decades ago) all
research was government sponsored so unbiased.
If our research people compared urea with sulphate of ammonia on an equal
dollar per hectare basis in the Waikato they�d find that SoA would win every
time as it has for me and dozens on my clients. Also there is less N loss by
volatilisation from SoA than from urea.
N needs S to work and in spring after our typical heavy winter rains and use
of single superphosphate in the autumn, S is low. Urea has none, while SoA
has 24%. Farmers who apply reactive phosphate and elemental sulphur in
autumn don�t lose all the S over winter and are better off financially and
animal health is far better which is a different subject. S is also
essential for the fixation of nitrogen by legumes.
2. N grows more grass, more crude protein and more total feed value, but
grows less clover so the pasture quality per kg is lower.
3. Clover Root Weevil is now in the Waikato and it reduces clover�s N
production so N helps keep the grass growing. Ca is too low in most Waikato
pastures (and many others) and if the correct amount of agricultural lime
were applied, less artificial N would be required and more pasture would
grow.
4. When establishing new pastures, applying N a few times until clovers are
producing it is very profitable and reduces new grass plant deaths through a
lack of N.
5. Modern high producing grasses respond to extra N even in perfect clover
based pastures on perfect soils. How much profit N makes depends on its
type, cost, animal returns, time of year, ability of the pasture to respond,
and most importantly, how profitably the extra grass is utilised.
Reasons for insufficient natural N in soils
� Poor drainage.
� Anaerobic, dead, tight, compact soils.
� Low organic matter (OM).
� N leaching out of low organic matter and sandy soils.
� Harvesting (rather than grazing crops and pastures) which lowers soil
OM.
� Low pH and/or low calcium levels.
� Inadequate balanced fertilisers applied.
� Poor pasture management such as pugging and allowing camping areas.
� Insufficient earthworms, or inactive ones. (See Earthworms)
� Insufficient legumes, or old low-N producing ones.
� Legumes not having the right N-fixing rhizobia.
Reasons why clovers don�t make sufficient N
� The manufacturing of nitrogen by clovers is relative to many things, but
mostly to the clover's own requirement for N, so, if artificial N is
applied, the clover promptly makes less, at the expense of the grasses
around it, so what happens eventually where artificial N is used repeatedly
at high rates, is clovers disappear and grasses take over. Small regular
applications with controlled grazing to prevent shading clovers doesn�t
adversely affect clovers to the same degree, but still does reduce the
amount of N they produce.
� Low-N producing clover varieties. Tahora makes twice as much N as the old
NZ white clover cultivars such as Huia which is in most New Zealand hill
pastures. Kopu 2 also makes a lot more than Huia and yields about twice as
much.
� The correct rhizobium is not present because clovers were not inoculated,
or not inoculated correctly because a wrong or expired inoculant was used,
and/or sun or heat killed the inoculant before or after inoculating the
seed. Clovers then have nodules that are white so contain no N. They should
be pink or brown inside. A white nodule also indicates low molybdenum in
soils.
� Insufficient Ca, P, K, S, Na, cobalt, copper, boron, molybdenum and/or
elements we don�t even know about. This latter statement is based on the
fact that after deep chisel ploughing, over trenches and next to gravel
roads, legumes frequently grow much better, possibly because of elements in
the subsoil. Marine RP also grows more clover than superphosphate (Winchmore
Research, NZ, trials) and many on farm comparisons and observations,
provided rainfall exceeds 800 mm (30 inches). Also pH must not be too much
above 6 and the soil must not be dead. RP�s don�t grow much pasture in dead
soils, even if it is acid which makes the RP available.
� Over-grazing which pulls up white clover stolons (surface runners) so that
the mother plant doesn't spread. Check white clovers when stolons are
spreading (some by a metre a year if not over-grazed) and you'll see that
90% of the clover nodules are on the stolons, not on the mother plant. In
Prince Edward Island, Canada, after winter snow and freezing, I noticed that
the only surviving white clovers were the stolons, not the mother plants
which had been heaved out.
� Cold temperature and low sunshine.
� Prolonged and/or excessive artificial N use which uses up soil organic
matter, so can create low humus soils. Depending on soil and other factors,
300 kg N/ha pa can do this under grazing where animal manure is also
returned to pasture. Lower amounts can do it when harvesting pasture. Clover
N fixation usually decreases by 50% of the amount of artificial N applied.
This increases the effective cost of applied N by more than 50%, because the
clover leaf percentage also decreases which lowers the feed value of pasture
and the animal production.
� As soils and pastures improve under controlled grazing the percentage of
grass increases resulting in fewer clovers to make N.
Best wishes,
Vaughan Jones
Hamilton
New Zealand
