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Also see the Technical
Specifications page for a full product analysis.
Reactive Phosphate Rock (RPR)
The element of Phosphorous is a key element for all plant, animal
and human health, playing a pivotal role in the cells energy systems.
Australia has insufficient plant available phosphate, with phosphatic
fertilisers being applied to agricultural soils for over 100 years.
Most phosphorous has been applied within manufactured chemical
substances such as superphosphate, triple superphosphate, Mono
and Di ammonium phosphate. Whilst these and other chemicals have
contributed to increased productivity, there has been a corresponding
decline in soil carbon levels, micro-organisms and the quality
of soil structure. Modern farming techniques and the excessive
us of chemicals, appear to be contributing to this problem. Sodic,
acid soils and land reversion are threatening to put millions
of hectares of rural Australian out of production. Consequently
the interest in sustainable agriculture, eco farming, biological
farming, organic farming and bio-dynamic farming are testament
to the change in attitudes.
Phosphate rock was deposited on seabed's millions of years ago
and is the bi-product of sea life deposits and phosphorous absorbed
from seawater. These deposits high in Calcium and phosphorous
have been uplifted and subsequently made available for mining.
Importantly the structures of these deposits broadly referred
to as fluoro apatites, have different crystal structures. Usually
as a consequent of intense pressure and heat the deposits have
metamorphosed into extremely hard dense crystals, with reduced
porosity and surface area and are consequently very stable and
unreactive. Scientist determined during the 19th century that
treating the ground rock with sulphuric acid would produce water-soluble
phosphate salt, or "super"phosphate.
The African rock phosphate, as used in FMN's "Phoroc®" is
unusual, as it has not had the intense heat and pressure experience
of most phosphate rock and has a crumbly, porous texture with
a high surface area. In addition there is a replacement of some
phosphate PO4 ions with carbonate CO3, the latter creating a less
stable structure and therefore the rock is able to readily release
the phosphate ion when exposed to the weak soil acids produced
by microbes and plants. Because these phosphates are able to react
with the weak soil acids, they are called "reactive" rock phosphates
(RPR).
The measure of reactivity is a key variable and the most commonly
used extractants are 2% formic acid, neutral ammonium citrate
and 2% citric acid. The P solubility i.e. reactivity, as determined
by these techniques provides a qualitative index related to the
rate at which the Phosphate rock dissolves and the P becomes available
to the plant. "Reactive" phosphate rock will, by definition, realise
at least 30% of elemental phosphate after 30 minutes, following
treatment with 2% citric acid. Whilst reactive indexes have not
been established or published, for the Australian competitive
products, this information will be determined.
Phosphate Availability
Phosphate availability or reactivity as measured by the reactivity
index, assures that FMN "Phosroc" has 12.5 to 13% elemental phosphate
all of which is plant available over time. The NZ Ministry of
Agriculture and Fisheries and Massey University have conducted
trials since 1981 comparing RPR and superphosphate. The results
showed Superphosphate pasture produced 3.3% more dry matter in
year 1, 1.9% more in year 2, but RPR was producing 1.6% more by
year three and provided maintenance levels of RPR were applied
continued to outperform Superphosphate.
The NZ trials supported by many other trials throughout the
world clearly show RPR to be as effective as acidulated Superphosphate
in trials exceeding three years.
However the conditions required for RPR to release Phosphate
are the pH must be below 6.5 and the annual rainfall must exceed
about 650mm. Whilst RPR is not "lost" in dry conditions, the necessary
reactions will not take place and phosphate deficiency can occur,
until rainfall or irrigation conditions return.
FMN also markets "Phosroc-S" which is reactive phosphate rock
with elemental sulphur and a partially acidulated form of RPR,
which is more suitable for low rainfall soils as it has a higher
degree of solubility.
Phosphate rate of release
RPR relies on weak soil acids to release the P, whereas acidulated
phosphates, such as Superphosphate are immediately soluble in
water. Therefore RPR cannot be used as a seed dressing with planting
but may be used in conjunction with a soluble phosphatic fertiliser,
effectively providing a quick and slow release phosphorous source.
RPR on an acid soil, with a pH of less than 6.5 will typically
take 3 years to dissolve, releasing about 35% of the phosphorous
in the first year.
Reduced phosphate loss
The Phosphate progressively released from RPR is more likely
utilised by plants and microbes, whereas the highly soluble acidulated
forms tend to be bound into highly insoluble deposits with Fe,
Al or Ca. Furthermore trials show that the loss of phosphates
to leaching is significantly reduced by using RPR, protecting
the environment and reducing waste.
Reduce soil acidity
RPR is a significant source of Calcium, and does not acidify
the soil unlike some salt fertilisers. In fact RPR may raise the
soil pH and save the cost of liming with every kilo of RPR providing
about half its weight in natural lime and dolomite.
Microbe Friendly
RPR is non "salting" and therefore less harmful to plant roots
and soil micro-organisms. Mycorrhiza fungi have a symbiotic relationship
with plant roots, translocating phosphorous into plant roots.
RPR stimulates microbial performance, unlike acidulated fertilisers,
which destroy beneficial soil fungi.
Organic Certification
Phosroc has been approved as an organic farm input by Bio-Grow
New Zealand, and certified organic by Certenz.
RPR Derived Products
FMN is also marketing a Rapid Release Phosphate RPR, designed
for immediate plant available phosphorus, but also has the sustained
release P expected of the RPR.
Phosroc Reactive Phosphate Rock (0-13-0 + Ca 35%)
Highly reactive phosphate rock or RPR, is a natural soft rock,
with 13% phosphorus and 35% calcium. It will release a third of
the phosphorus in the first year and the balance over about 3
years, given reasonable moisture and a pH of 6.5 or below. The
calcium substitution in this soft rock provides half the liming
effect of Agricultural lime.
Farmers Marketing Network uses only the worlds best reactive
material, with proven phosphate and liming performance, is bio-friendly,
non-acidifying, and minimizes phosphate loss from leaching or
sorption.
The product has "Organic Farm Input Certification" under NZ certification
agency Bio-Gro New Zealand. Certenz, a Jas-Ans accredited certification
body, certifies the process.
Also see technical
specifications
Phosroc - S (0-11.5-0+Ca32%+S10%)
Highly reactive RPR with added elemental sulphur.
Also see technical
specifications
Super Phosroc (PAPR) (0-15-0 + S2.5%)
Reactive Phosphate Rock partially acidulated to provide a 50/50
quick and sustained release phosphate with 2.5% sulphur sufficient
to address deficiencies present in most Australian soils.
Packaging:
40 Kg bags, 25 per pallet. 25 Kg bags, 40 per pallet.
1 tonne bulka bags.
Application:
Normal spreader. Rate 1 bag(40kg) to 4 bag (160kg)
depending on crop or requirements.
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