AU2012216532A1

AU2012216532A1 - Improvements in and relating to soil treatments

Info

Publication number: AU2012216532A1
Application number: AU2012216532A
Authority: AU
Inventors: Robert Hamilton Hall
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-08-30
Filing date: 2012-08-30
Publication date: 2013-03-21
Anticipated expiration: 2032-08-30
Also published as: NZ594880A; AU2012216532B2

Abstract

Abstract This invention relates to improvements in and relating to soil treatments. The soil treatment includes a composition for usc as a fertiliser. The soil composition is in granular form. The composition includes particulate reactive phosphate rock (RPR). The RPR is finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns. The composition also includes Muriate of Potash (MOP) intimately combined and binding with the RPR. The MOP also acts as a dispersant and provides additional agronomic benefit to the composition. The composition also includes a fluid. The composition also optionally includes other active agents, including ground elemental sulphur, nitrogen and trace elements.

Description

5 IMPROVEMENTS IN AND RELATING TO SOIL TREATMENTS Technical Field This invention relates to improvements in and relating to soil treatments. 10 In particular, this invention is directed to providing a substantially improved fertiliser composition. In addition, the composition is further provided in a granular form for ease of application. Said fertiliser composition includes Reactive Rock Phosphate (RPR) finely ground to increase the reactivity of the RPR, yet at the same time effect a composition with low cadmium 15 content. Further, the composition also includes a binding agent. The binding agent is selected such that whether the composition is applied solely as a RPR composition in conjunction with the binding agent or is applied as a composition including RPR and binding agent along with other active agents, including ground elemental sulphur, nitrogen and various trace elements, the binding also acts as a dispersant and provides additional agronomic benefit to the composition. 20 It is envisaged the invention will be applicable to any situation, for example agricultural, horticultural, forestry, commercial, industrial or domestic situations where soil treatments are required. However, the invention may have applications outside this field. 25 Background Art Cadmium is a naturally-occurring, non-essential heavy metal which is present at low concentrations in air, water and soils. Cadmium naturally occurs in phosphate rock, from which phosphate fertiliser is made. Phosphate is essential for plant growth and maintaining the agricultural productivity of most countries, including New Zealand. 30 However, cadmium can accumulate in soils from ongoing phosphate-based fertiliser application. There is evidence that cadmium levels in New Zealand's soils are slowly increasing. Accumulation rates in soils vary between regions of New Zealand due to differences in land use history, phosphate fertiliser cadmium content, total fertiliser use, soil types, climate, and a 35 number of other variables. This raises the potential for higher cadmium concentrations in some food products grown on soils with elevated cadmium levels.

5 Phosphate based fertilisers are essential to New Zealand agriculture. The fertiliser industry needs to find ways to reduce the amount of cadmium entering the environment. For example, the European Commission has issued the following guidelines in regard to cadmium levels in fertiliser. - For low fertiliser cadmium concentrations (between 1 to 20 mg Cd/kg PzO), cadmium in 10 soil tends to accumulate relatively slowly, or decreases after 100 years of application due to net removal rates (leaching, crop uptake) exceeding inputs; For fertiliser with Cd concentrations of 60 mg/kg P 2 0s and above, accumulation in agricultural soils over 100 years is relatively high. Due to the combined effect of minor losses, soil accumulation was not expected to occur where 1-5 fertilisers contain 20 mg Cd/kg P 2 0 5 (4 mg/kg as superphosphate), or less. Ideally a phosphate fertiliser with less than 20 mg cadmium/kg P 2 0 5 (6ppm) should be used in Ncw Zealand. However, most superphosphate fertilisers have at least 24 ppm cadmium content. The >24ppm cadmium content is well over the 6ppm level required to prevent accumulation in the environment and as, such, superphosphate fertiliser is, at present, the main. (99%), source of new 20 cadmium introduced to agricultural catchments. Currently, it is difficult and expensive to remove the cadmium from superphosphate. The maximum concentration of cadmium allowable in phosphate fertilisers varies from country to-country. New Zealand has a voluntary limit of 120 md Cd / kg P205. As mentioned above .25 this level is not sustainable and will see an increase in cadmium in the environment, eventually to levels dangerous to human health. An alternative phosphate fertiliser to superphosphate is reactive rock phosphate (RPR). There are many grades of rock phosphate available around the world. The agronomic value of rock 30 phosphate is dependent on the following parameters: total phosphorus pentoxide (P2 0 5) content, particle size distribution, and solubility. Solubility and hence the rate of reactivity in the soil is measured by tests known in the prior art, such as the 2% citric acid test. If the solubility of the phosphorus in a phosphate rock in the citric 35 acid laboratory test is at least 30% of the total, such a product is labeled a 'Reactive Phosphate Rock', and the majority will have typically become plant available within two years of application. Solubility can also be measured as percentage phosphorus pentoxide (% P 2 0 5 ). In 2 5 this case a figure of >9.4 (soluble P 2 0s as a percentage of the rock phosphate) indicates a reactive rock phosphate. Fine grinding has also been used as a method to increase the reactivity of phosphate rock. Grinding provides 'fresh' particle surfaces, increases geometric surface area, and increases 10 solubility measurements. The problem with finely ground rock phosphate is fine dust and the cost of fine grinding. Studies by the International Fertiliser Development Center (IFDC) of two (phosphate rocks) PRs with high VAC solubilities indicated that grinding f-om plus 200 mesh Tyler (75 pm) to 100-percent minus 200 mesh increased specific surface area from 40 to 50 15 percent. The NAC P;Oj solubilities of these PRs and a third rock increased from about 60 to 120 percent with grinding to minus 200 mesh. (1) The solubility of phosphate rock (PR) increases with decreasing particle size (Chien, 1993, 1995), However; a very fine grinding of a low-reactivity PR cannot increase its solubility significantly enough to compensate for the nature of its low reactivity owing to 20 low CO 3 substitution/or P04 in the apatite structure. It is possible to find "medium" classified phosphate rock and, through fine grinding, increase the solubility to the point where it can be classified as "high" reactivity. A range of phosphate rocks are available from around the world where the cadmium content varies dramatically. There are 25 several sources of "medium" reactivity phosphate rocks with suitably low cadmium levels. It is also relevant to this discussion to be aware that studies have shown at least 50% of the cadmium in rock phosphate is not water soluble in comparison to superphosphate. Potash is the common name for various mined and manufactured salts that contain potassium in a 30 water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains. Potash is produced worldwide at amounts exceeding 30 million tonnes per year, mostly for use in fertilisers. Worldwide 90% of processed potassium is used as fertilisers. Muck, peat and sand based soils are typically potassium deficient. Potassium salts can be applied 35 to all soils and crops that are not sensitive to chlorides. Soluble soil-potassium is absorbed and retained by soil colloids. This characteristic helps prevent leaching from the soil. The roots are then able to usc the potassium in ionic form. 3 5 Muriate of Potash (MOP) typically contains 50 - 60% potash. Muriate of Potash is also called Potassium Chloride, chemically KC1, yet having a composition of KCI:NaCI (95:5 or higher). In its pure state, MOP is a white crystalline solid but, MOP varies in colour from pink/brown or red to white depending on the mining and recovery process used. Commercially MOP is available in fine, coarse and granular grades. 10 Muriate of Potash (MOP) is produced in a granulated and in a non-granulated fbrin (MOP 'fines'). The majority is then dry blended with other fertilisers to make a multi-nutrient fertiliser For example: " Superphosphate 15 - Sulphate of Ammonia e Urea Coarser MOP blends well with N-P compounds to form NPK-blended multi-nutrient fertilisers. In any agricultural, horticultural, forestry, commercial, industrial or domestic situation where at 20 least optimal growth of vegetation is required or desired a number of factors interplay. Not the least of such factors is soil type/structure and nutrient availability. Soil structure has a major influence on water and air movement, biological activity, root growth, seedling emergence and plant retention. Soil structure is determined by how individual soil granules clump and thus the arrangement of soil pores between them. 25 Soils also differ in nutrient profile. For example, most soils in South Africa are poor in phosphorus and do not contain enough to sustain normal plant growth. Phosphorus deficiencies by extension therefore occur in ruminants grazing on phosphorus-deficient pastures. By comparison, soils in Western Australia are very old, highly weathered and deficient in many of 30 the major nutrients and trace elements zinc, copper, manganese, iron and molybdenum. Accordingly, fertilisers are routinely applied to such soils to achieve the nutrient profile desired to sustain plant growth for harvest and/or to provide nutrients to grazing stock animals. Fertilisers are nutritional compounds given to plants to promote growth. Fertilisers typically 35 provide macro and/or micronutrients in varying proportions. Those required in large quantities for plant growth include nitrogen, phosphorus, potassium, sulphur, calcium and magnesium (macro-plant-nutrients), and those required in much smaller quantities include copper, zinc, manganese, boron, iron and molybdenum (micronutrients). The most commonly available 4 5 fertilisers provide the three major macronutrients (nitrogen, phosphorus, and potassium). For example, an 18-51-20 NPK fertiliser would contain by weight, 18% elemental nitrogen (N), 22% elemental phosphorus (P) and 16% elemental potassium (K). Fertilisers may be applied as organic or inorganic fertilisers. Organic fertilisers include manure, to slurry, worm castings, peat, seaweed, sewage, guano, green manure crops, compost, blood meal, bone meal, seaweed extracts, natural enzyme digested proteins, fish meal, and featber meal. Naturally occurring minerals such as mine rock phosphate, sulfate of potash and limestone may also be considered to be organic fertilisers. A range of manufactured fertilisers are also available For example, nitrogen fertiliser is often synthesized using the Haber-Bosch process, which 15 produces ammonia. This ammonia is applied directly to the soil or used to produce other compounds, notably ammonium nitrate and urea, both dry, concentrated products that may be used as fertiliser materials or mixed with water to form a concentrated liquid nitrogen fertiliser. Ammonia can also be used in the Odda Process in combination with rock phosphate and potassium to produce compound NPK fertilisers. 20 Fertilisers may be water-soluble (instant release) or relatively insoluble (controlled/sustained/timed release). However, whilst fertilisers may be applied to meet nutritional needs of plants, they are less likely 25 to be tailor-made in respect of particle distribution to suit the soils to which they are applied. Further, whilst various applications may be tailored with respect to the dispersal as fast, slow, medium release products over time, they are typically less tailored in respect of particle distribution to suit climatic conditions as required. 30 This can lead to the problem of over-fertilisation which is primarily associated with the use of artificial fertilisers and results from the massive quantities applied and the destructive nature of chemical fertilisers on soil nutrient holding structures. The high solubilities of chemical fertilisers also exacerbate their tendency to degrade ecosystems. 35 There are also problems associated with storage and application of some soil treatment products and fertilisers. For example, fine elemental sulphur is both explosive and a health hazard. Nitrogen fertilisers in some weather or soil conditions can cause emissions of the greenhouse gas, nitrous oxide (N 2 0). Ammonia gas (NH 3 ) may be emitted following application of inorganic 5 5 fertilisers, or manure or slurry; and ammonia can also increase soil acidity (lowering of soil pH). Excessive nitrogen fertiliser applications can also lead to pest problems by increasing the birth rate, longevity and overall fitness of certain pests. Whilst is also possible to over-apply organic fertilisers; their nutrient content, their solubility and 10 their release rates are typically much lower than chemical fertilisers. By their nature, most organic fertilisers also provide increased physical and biological storage mechanisms to soils, which tend to mitigate their risks. However, again the application of such fertilisers is not typically geared to being tailored made for specific soil types. 15 For these reasons, it is important to know the soil type, the nutrient content of the soil and nutrient requirements of the crop, so that desired outcomes can be carefully balanced with the application of soil conditioning and/or fertiliser products. By careful monitoring of soil, climatic conditions and crop requirements, wastage of expensive fertilisers and potential costs of cleaning up any pollution created can be avoided. 20 While the present invention has a number of potentially realisable applications, it is in relation to problems associated with existing soil treatment and fertilising systems that the present invention was developed. More specifically, it was with regard to the issues of providing a treatment system more appropriately tailored to specifically suit the specific application, soil conditions and 25 climatic conditions, including temperature. It was also developed with safety and health issues typically associated with such systems, that the present invention was developed. Finally, it was having regard to the need to provide a treatment system that would easily disperse in the soil, provide the desired effect, had sufficient compressive strength to ensure that the product did not break-up during storage, transport and handling and that would minimise waste of product when 30 applied. It would be useful therefore, to have a soil treatment system that: 1. Could be tailor-made to specifically suit the specific application, soil conditions and 35 climatic conditions including temperature; and 2. Considered and improved on safety and health issues of existing systems; and 3. Was effective at mobilising nutrients and/or soil enhancing components so that good plant growth could be achieved with lower nutrient densities; and 6 5 Effected less wastage of nutrients and/or soil enhancing components through run-off, air dispersal and so forth; and 5. Minimised the build-up of potentially toxic products in soils and plants; and 6. Released nutrients at a determined, more consistent rate, helping to avoid boom-and bust patterns; and 10 7. Helped, where applicable, to retain soil moisture, reducing the stress to plants and soil structures due to temporary moisture stress; and 8. Contributed where appropriate to improving the soil structure; and 9. Minimised the possibility of "burning" plants with concentrated chemicals due to an over supply of some nutrients; and 15 10, Provided a more cost effective alternative to present systems employed; including costs of handling, transportation and application costs, and 11- Provided a consistent product, so that accurate application of nutrients to match soil type and plant production was possible.; and 12. Would be easy to use. 20 It would therefore be advantageous to have an invention that offered at least some, if not all, of the potential advantages of the above proposed treatment system. It is therefore an object of the present invention to consider the above problems and provide at least one solution which addresses a plurality of these problems. 25 It is another object of the present invention to at least provide the public with a useful choice or alternative system. Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. It should be appreciated that variations to the 30 described embodiments are possible and would fall within the scope of the present invention. Disclosure of Invention The present invention is directed to using improved grinding and granular compaction techniques 35 to increase the reactivity of RPR. The RPR is preferably selected with the first sclcction criteria being low-cadmium (<6ppm) rock phosphate. 7 5 An example of a "medium" reactivity phosphate rock with a low cadmium level (5.2ppm) is Egyptian phosphate rock. This invention will enable such low cadmium phosphate rock (PR) to be widely used in New Zealand. The RPR is preferably finely ground to improve its "reactivity", 10 The RPR is preferably combined with at least one other agent. The at least one other agent preferably operates as a binding agent 15 The at least one other agent also preferably operates as a dispersing agent The at least one other agent, in terms of a binding agent and a dispersing agent, is preferably Muriate of Potash. 20 The resultant composition of finely ground reactive rock phosphate and the at least one other agent preferably provides a resultant composition capable of being manufactured in granular form. Preferably, the granules can then be applied to soils as a "high" reactivity reactive phosphate rock 25 (RPR) with very low cadmium, thus preferably mitigating the agricultural system accumulation problem. The present invention is specifically directed to applying finely grinding and compacting techniques to utilise lower cadmium rock phosphate. 30 This invention enables an RPR granule with less than 6ppm cadmium, that has a soluble Phosphate content of greater than 30% (as measured by the 2% citric test) and that is also able to be accurately spread and safely handled. 35 At the present time, there is no known granular RPR manufactured today with less than 6ppm cadmium content, which also passes the 30% Citric Acid Solubility Test S In addition, cadmium is typically softer than the phosphate rock and therefore the cadmium is typically found in the finer portion of the ground phosphate rock. Cadmium can be removed by heat treatment (typically 900*C). This is achieved by separating out the finer fraction and heating only this material, In this way large cost savings can be made. 10 The present invention is therefore also based on using, the grinding technique to achieve finely ground phosphate rock particles in combination with the use of low cadmium phosphate rock and the method of separating fines, the heating of the fines and reducing the cadmium to a level of preferably less than 6ppm. This would open up many more sources of RPR, which can safely be used without further exacerbating the cadmium problem in soils to which phosphate fertilisers are 15 applied. A further advantage of these fines is that the size is suited to flash calcining. Flash calcining is a simple cost effective method of heating the fines to +900 0 C and removing the cadmium in the gas flow. 20 Grinding of RPR can be undertaken by a variety of means. Preferably the use of a hammer-mill enables the selective grinding of softer material. This would aid in the selective grinding of the softer cadmium fraction, 25 Preferably, the phosphate rock granules would be ground to particle sizes where at least a significant proportion less that 75 micron. However, a range of particle sizes will be achieved. Preferably a the finer fraction will include particles having sizes of less than 75 micron, and even less than 45 micron. The fine grinding technique employed will result in particles having sizes 2mm to submicron. 30 Preferably, the present invention will provide RPR ground to produce granules which: 1. Meet the standard citric acid test for a reactive phosphate rock (RPR) being less than 9.4%. 2. Match the regional temperature variations. For example: colder regions will use granules 35 with finer particles. 3, Suit soil conditions 4. Suit the rate of release desired. 9 5 5. Take into consideration whether or not the RPR is be heat treated to reduce or further reduce the cadmium levels Preferably, Muriate of Potash (MOP) will be used as a binding agent in the granule compaction process. MOP has significant agronomic value in its own right. 10 'However, bentonite is also suitable as a binding agent and has the added benefit of being alkaline. Preferably, the present invention also includes additional agents in relation to the composition production, as may be required to achieve a preferred and/or predetermined fertiliser for 15 application to specific soils. Preferably, the composition also includes elemental sulphur as a further agent which may be combined with the RPR/MOP composition. 20 Preferably, the elemental sulphur is finely ground. To the applicant's knowledge, the application of Muriate of Potash (MOP) as a binding agent/dispersing agent for use in RPR/sulphur fertiliser granules has not been known in the prior art. In addition, to the applicant's knowledge, the application of Muriate of Potash (MOP) as a 25 binding agent/dispersing agent in high-pressure or low pressure formed granular fertiliser products has not been known in the prior art. Preferably, in accordance with one embodiment of the present invention, the finely ground fertiliser composition includes MOP, prepared RPR (with low cadmium level), prepared 30 elemental sulphur and a fluid. Preferably the fluid provides moisture to the composition. Preferably the fluid is water. However, other fluids may be used as suitability is identified. 35 Preferably, the fertiliser composition includes additional optional components. Such additional components may be included to add trace elements, provide other benefits to the composition, and/or be used to bind the various components in the composition together to contribute to the formation of the fertiliser in a granular form. 10 5 Preferably the fertiliser product so produced is applied in a granular form. For example, in accordance with one embodiment the component contribution in the fertiliser composition includes on a percentage weight:weight basis: 10 Muriate of Potash (MOP) 1-40 Reactive Rock, Phosphate (RPR) 10-90 Sulphur (elemental) 0-40 Fluid 2-8 *Other 1-10 15 where "other" includes trape elements, components that provide other benefits to the composition, and/or are used to bind the various components in the composition together to contribute to the formation of the fertiliser in a granular form. Phosphorus is essential for the division of cells at the growth points of the plant roots 20 underground, as well as at the growth points of plants above the ground. If the plants take up too little phosphorous, they grow slowly and remain small, and the ripening of especially grain seeds is slowed down. Too much phosphorous in the soil or too much of it added by way of fertiliser is not really harmful for plant growth, but it is a waste of money. 25 Elemental sulphur is a valuable plant nutrient often required due to sulphur deficient soils. Preferably, the granule or pellet size for the granular form of the composition is 2 - 8 millimeters. Preferably the pellet size for the granular form of the fertiliser composition is 6 millimeter-sized 30 pellets. In accordance with another aspect of the present invention, the preferred components in the preferred compositions are finely ground to particles sizes which benefit the predetermined and desired availability of the fertiliser components in the composition when the granular form is 35 applied to soils, Preferably, in accordance with another aspect of the present invention, the fertiliser composition is prepared via the following steps: 5 a) The MOP is preferably inter-ground with the reactive rock phosphate (RPR) and/or elemental sulphur to produce a thorough mix having preferred particle sizes. b) Fluid may be added to the mix to improve the dispersion of MOP. c) Pressure is then applied by means of a roller pellet press to produce stable, dust free granules. 10 The prepared granules are preferably dricd or cooled to improve the hardness of the granules/pellets, depending on the pelletising/granulation technique employed. In accordance with another aspect of the present invention, the MOP may optionally be dispersed 15 in the fluid and then added to the dry granule components. Preferably, the fluid is water; although, any other fluid identified as suitable for use or adapted for use with the present invention may be used, 20 Preferably the grinding process effects the components having a preferred particle size range. Preferably, high pressure is applied by means of a roller pellet press to produce stable, dust free granules. However, other suitable high pressure granulating/pelletising techniques may be used or adapted for use with the present invention. 25 Using high pressure techniques contributes to producing harder pellets/granules which are drier. Granules formed by high pressure need only ambient air cooling for hardening to occur due the temperature at which the pellets leave the press (approx. 60*C). 30 Alternatively, a low pressure process may be used. Such low pressure process could involve pan granulation. However, other suitable low pressure granulating/pelletising techniques may be used or adapted for use with the present invention. Granules formed by low pressure techniques preferably need to be dried either by drying in 35 sunshine or on a fluid bed, or via any other suitable drying means. it is to be noted that MOP is a salt and recrystallizes when it dries. This characteristic imparts strength to the fertiliser granule. 12 5 MOP preferably also used as it is highly water-soluble and rapidly dissolves when coming into contact with moisture. This characteristic imparts excellent dispersing ability to the granules when applied. Granules produced at low pressure via the present invention preferably disperse in water in 2-3 10 seconds up to 10 hours. Granules formed at high pressure via the present invention preferably disperse in less than 10 minutes but up to 24 hours. 15 Preferably the pellets/granules produced are stable, and dust free. This is advantageous when storing, transporting and applying the fertiliser granules. The method of manufacture of the granules is relevant to achieving this. As a result of the method of pellitising/granulation used, preferably the granules have a typical 20 crush strength for an RPRMOP granule of between 3 - 3.5kg. However, crush strengths range from 1. - 10 kg. The use of MOP therefore provides a potentially realizable advantages to the present invention, as other dispersants commonly used in fertiliser granules typically have no agronomic value in 25 themselves. For example: bentonite clays, lignin sulphonates. However, MOP contains potassium in a water-soluble form and potash is important for agriculture because it improves water retention, yield, nutrient value, taste, colour, texture and disease resistance of food crops. It has wide application to fruit and vegetables, rice, wheat and other grains, sugar, corn, soybeans, palm oil and cotton, all of which benefit from the nutrient's quality enhancing 30 properties. MOP has significant agronomic value in and of itself and often needs to be applied. This invention is directed to provide a soil treatment system. The soil treatment system is 35 preferably directed to improving soil condition and/or soil-nutrient availability for plants. The term treatment as used in this specification typically will involve a knowledge of the condition of the soil preferably via prior analysis and involve administration to the soil, or a regimen of 13 5 applications, of particular preferred composition which aids in improving at least the soil condition (including structure) and/or soil nutrient content. Preferably, the soil treatment system is provided in granule form for application to soils. 10 For the purpose of the present invention the term granule shall mean any small blocks of molded and/or compressed material and/or otherwise formed and shall include varyingly shaped and sized pellets, fragments, briquettes and so forth. The use of the term granule should therefore not be seen as limiting this invention. Prills may also be formed subject to use of the appropriate technique. 15 Preferably, the granule is specifically tailor-made in respect of the particle distribution of its components to suit various applications, soil and climatic conditions (including temperature) as required, The granule may have varying composition depending on the components of the granule and the application it is designed for. 20 Preferably, the granule is specifically tailor-made in respect of particle size and/or surface area of its components to suit various applications, soil and climatic conditions (including temperature) as required. The granule may have varying particle sizes within its composition depending on the components of the granule and the application it is designed for. 25 Preferably, the particle size is optimised by fine-grinding and classification to suit differing soil conditions and the purpose for which it is being used. Preferably, the granule components are tailor made to suit specific soil types in particular 30 countries and for particular soil types in particular regions within said countries. Preferably, the granule, following application, is required to make the components of the granule available within or on the soilt To achieve this, the granule preferably disperses at a preferred rate. 35 Preferably the dispersion of the granule enables the components of the granule to be available. Howcvcr, the individual components of the granule may vary in the rate at which cach will bc directly available for the specific need. For example one component may be immediately 14 5 available for use - whether as a nutrient or soil conditioner; whilst others may be released in the soil over time, or at different rates, or with the onset of particular climatic or soil temperature/conditions as required. In some embodiments of the invention, the granule may be prepared to enable either or both 10 immediate dispersion of the granule and immediate release of the granule components into or onto the soil. In other embodiments, the granule may be prepared to enable delayed dispersion of the granule and controlled release of any or all of the granule components over time, or following a set period after application of the granules, or in preferred conditions. In yet further embodiments, the granule may be prepared to enable immediate dispersion of the granule and 15 then controlled release of any or all of the granule components over time, or following a set period after application of the granules, or in preferred conditions. For example, in some embodiments of the present invention, the granules may be coated to delay dispersion of the granule per se or delay release of a specific component. In other embodiments, the granule may be formulated to disperse in water within a few minutes yet delay release of a component. For 20 example, coating the granules with a nitrogen inhibitor can control the release of urea, thereby reducing leaching of nitrate and volatilisation of nitrous oxide and ammonia. In this case, the granule is simply dispersing, but it should be appreciated the availability of the particular nutrient component is then determined by the specific solubility of that individual nutrient component. 25 Pressing methods are preferably applied in the formation of the granule form of the product. Any suitable press method may be developed or adapted for use in achieving the present invention. Preferably however, the granule does not break-up during storage, transportation and application. To achieve this, the method of manufacture is directed to producing a granule having a preferred 30 compressive strength (or crush-strength). The compressive strength is directed to ensure that the granule which results is less likely to breakdown during handling, transportation or application. Preferably, the granules are uniform in size. The uniform sized granules contribute to more accurate spreading. However, the granules may be varyingly shaped. 35 Preferably, the granules are colour coded to ensure the correct formulation is applied to a particular treatment site, for a particular end result. I S 5 It is important to produce granules with optimum storage, handling and application characteristics under a full range of conditions. The following techniques may be used to achieve this, by: 10 a) Minimising the surface area of the granules - by producing smooth surfaced granules. Granules produced by various means can typically have rough surfaces and therefore a higher overall surface area. A pellet press can be used to produce granules with smooth sides and clean-cut ends. Briquettes are an example of granules produced which are typically smooth on all sides. Often the compression stage can lead to a sheen, often 15 noticeable on briquette-type granules. b) Minimising the bulk surface area. The overall surface area of the bulk fertiliser granules can be reduced by producing larger sized granules. 20 c) Minimising the amount of moisture present in the granule. This will especially mitigate problems encountered due to moisture absorption under high humidity conditions. d) Producing harder granules. Granules produced under higher pressure will be harder and have better handling characteristics. 25 e) Post-production heating of the granules. Such heating can be applied to produce a hardened surface. This may also further reduce retained/absorbed moisture following production of the granules. f) Coating of granules with lime powder can be undertaken. 30 g) Storage of granules in preferred conditions for a preferred period of time. It may be that such techniques are employed to also affect the dispersion rate of the granules. For example, newly produced granules may disperse more quickly than granules which have been 35 stored for a period of time before application onto the soils - whether such changes are effected by further drying of stored granules, changes in pH over time or other such factors. RPR when ground and classified to a desired particle size distribution provides an excellent controlled-release phosphate source. 16 5 An important factor which determines the reactivity of RPR is fineness of particle size. The present invention describes the fine grinding of RPR to preferred particle sizes. There is however a limit on how fine RPR can be ground because of transportation and usability constraints. Accurate spreading of finely ground reactive phosphate rock is also difficult due to the drifting of fine particles. Granulation of fine RPR materials overcomes these practical problems enabling a 10 much finer RPR to be transported and applied. Granulation of the product provides an advantage in reducing dust problems associated with finely ground RPR. Fine grinding and granulation also enables lower grades of KPR to then be used, lowering the cost of the producing granules containing RPR. Of commercial benefit is the availability for use of 15 previously uneconomic RPR deposits through a fine grinding and granulation process. RPR with poorer reactivity can be upgraded by grinding to a fine state. To improve handling or application of materials so finely ground they must be granulated or mixed with a fluid. For example when RPR is ground to 100% passing 800 micron it fluidizes 20 when handled or subject to vibration. In accordance with the present invention, two granulation processes are described, although other known pressing methods can be used. In some other embodiments sheets may be formed by means of a doable-roll chinsolator applying approximately 2000kg of pressure. The pressed 25 sheets are then broken up by means of a rotating finger type device to produce 0.2-8mm long granules. Or, pellets are formed by means of a double-roll pressure pelletiser device applying approximately 2000kg of pressure to produce granules 1-5mm long. The granules may be various shapes. Uniform-sized granules have better spread characteristics than a non-granulated product. This helps ensure more accurate spreading. 30 The two key criteria for evaluating a fertiliser granule are crushing strength and water dispersion. The first relates to the ability to produce a dust-free product the second ensures that the phosphate and sulphur are quickly made available in the soil. Crush strength gives an indication of the strength characteristics of fertiliser granules. Granule strength plays an important role in the 35 storage, transportation and application of granular fertilisers 17 5 As the pressure at which the granules are formed increases (from 500 to 2000kg) so does the crush strength of the granules (for various granule compositions). By controlling the pressure at which granules are formed it is possible to produce a granule with the desired strength characteristics. 10 According to one aspect of the present invention there is provided a method for maximizing the availability of at least one soil treatment composition, said soil treatment composition containing at least one active component, said method including the steps of: a) Selecting the soil treatment components required; and b) Preparing said components in dried form, said components being ground to a preferred particle 15 size; and c) Mixing said components together; and d) Adding a preferred quantity of fluid to the mixed components; and d) Applying pressure to a quantity of said component-solvent mixture to form granules of the composition; and 20 said method characterized by the particle sizes of the components being specifically targeted for use with a particular soil type and/or treatment requirement. According to another aspect of the present invention there is provided a method, substantially as described above, wherein an optional dispersion and/or binding agent is added to the component 25 mix. According to another aspect of the present invention there is provided a method, substantially as described above, wherein at least one of the active components also acts as dispersion and/or binding agent. 30 According to another aspect of the present invention there is provided a method, substantially as described above, wherein the fluid includes at least water. However, other fluids, such as oils and so forth may be used (including a fish, or avegetable oil - such as a triglyceride). 35 According to another aspect of the present invention there is provided a method for maximizing the availability of at least one soil treatment composition via prolonged release of the components on to and/or into the soil, said method including the step of; grinding the components to achieve a preferred particle size, said particle size being adapted to the soil type and requirement and 5 providing an increased surface area to improve availability of the component in to or onto the soil. According to another aspect of the present invention there is provided a method substantially as described above achieved via coating of the granule to effect delayed release of the components 10 over a period of time after introduction of the granule on to or into the soil. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein the delay in release of the components of the granule is accomplished by encapsulating the granule within a 15 dissolvable or degradable protective layer. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein a quantity of the components of the granule is released substantially continuously, once release is initiated, for the 20 intended life of the granule. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein there is provided an initial boosted release rate of components from the granule following introduction of the 25 granule on to or into the soil. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein there is provided at least a second boosted release rate of components from the granule following introduction of the 30 granule on to or into the soil. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein the interval between the initial and second boosted release rates corresponds to a predetermined ideal period 35 between release and action of the first component and release and action of a second component. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein a boosted release 19 5 rate of the components of the granule is accomplished by providing a secondary component having different release rate characteristics than the first component, According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein a boosted release to rate of the components is accomplished by providing one component having an exposed surface area greater than other component(s) in the granule. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein one component 15 operates as a carrier matrix system through which at least a second component is dispersed. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein the carrier matrix component dissolves when exposed to the environment into which it is introduced, to expose at 20 least one other component in a time release manner. According to another aspect of the present invention there is provided a soil treatment composition in the form of a granule substantially as described above wherein the granule, in its entirety, is substantially biodegradable within the soil treatment environment to which it is 25 introduced. A soil treatment composition in granular form, said granules have a mechanical resistance, dimensions and weights being appropriate for the distribution and the mechanical application on the ground and in the ground, the granules being characterised in that they include finely ground 30 particulate components. A soil treatment composition in granular form, characterized in that the dimension of fine particles do not exceed a preferred dimension as required. 35 A method of preparation of a granular soil treatment composition, wherein the particles of the components are mixed with a binding agent in an effective proportion to bind the particles in the form of granules having dimensions and weights appropriate for a mechanical application. 20 5 The granules may be applied via aerial top-dressing, mechanical spreaders, manually. One aspect of the present invention is to therefore provide a fertiliser granule, said granule including one or more of a binding agent, a dispersing agent and optimum amounts of particulate plant nutrients which can be released in a timely fashion to the soil to achieve rapid availability 10 for plants, said granule being characterised by said particles being sized for optimum benefit having regard to the soils type, different climatic conditions and the different plant nutrient release rates required. Having regard to the use of Reactive Phosphate Rock (RPR) in relation to a granule for use in soil 15 treatments as a fertiliser, at least one factor which determines the reactivity of RPR is fineness, Practically, there is a limit to how fine RPR can be ground due to its transportation and usability constraints. Granulation of fine RPR materials overcomes such practical problems enabling a much finer RPR to be transported and applied. Accordingly, lower grades of RPR are then able to be used which in turn provides realisable benefits in lowering the cost of producing granules 20 containing RPR. Prcviously uneconornic RPR deposits can therefore become a more economic source through a fine grinding and granulation process. Reactive Phosphate Rock (RPR) with poorer reactivity can thus be upgraded by grinding to a fine state. 25 In the present example, it may also be appreciated that fine elemental sulphur is both explosive and a health hazard. The granules of the present invention which may include elemental sulphur are dust-free. Therefore, the granules are able to be stored, transported and applied with little risk of hazardous sulphur dust being released. 30 In addition, the granule form avoids the limitations of traditional mixed fertilisers which are in powdered or loose form. Such fertilisers are-typically transported at some stage. The vibrations generated during transportation can cause the different component nutrients to separate out due to their varying densities. When the fertiliser is then applied there is the potential for uneven distribution of the components of the fertiliser and so some areas may remain or may result in 35 being more deficient in a particular component when, compared to another. It will therefore be appreciated that the invention broadly consists in the parts, elements and features described in this specification, and is deemed to include any equivalents known in the art 21 5 which, if substituted for the prescribed integers, would not materially alter the substance of the invention. Variations to the invention may be desirable depending on the applications with which it is to be used. Regard would of course be had to effecting the desired concentrations or volume to volume 10 ratios of the components of the granule, the various components of the granules, the dimensions of the granule, the dissolution rates, the method of application of the granules and so forth as required to effect the desired outcome. Whilst some varying embodiments of the present invention have been described above and are to 15 be yet exampled, it should further be appreciated different embodiments, uses, and applications of the present invention also exist. Further embodiments of the present invention will now be given by way of example only, to help better describe and define the present invention. However, describing the specified embodiments should not be seen as limiting the scope of this invention. 20 Brief Description of Praings Further aspects of the present invention will become apparent from the following description, given by way of example only and with reference to the accompanying drawings in which: Figure 1 is a table showing maximum levels of Cadmium allowed in phosphate fertilisers 25 in some countries around the world, relevant to the present invention; and Figure 2 is a table showing a range of phosphate rocks from around the world (where the cadmium content varies dramatically), in accordance with one embodiment of the present invention; and 30 Figure 3 are tables showing some examples of the components of preferred fertiliser compositions in accordance with some embodiments of the present invention; and Figure 4 is a table showing particle size distribution/range of cadmium in RPR finely 35 ground particles, relevant to the present invention; and igure 5 is a cost comparison table showing the cost of use of Superphosphate based applications in New Zealand, versus the application of the RPR granule of the 22 5 present invention, in accordance with one embodiment of the present invention; and Figure 6a is a table showing granule strength and dissolution times of pressure formed RPR/MOP granules of various percentage weight:weight compositions; and 10 Figure 6b is a table showing table providing granule strength and dissolution times of tumble agglomeration RPR/MO? granules of various percentage weight:weight compositions; and 15 Figure 6c is a table showing results of RPR particles screened through a sieve of less than 1mm; and Figure 6c is a table showing results of RPR particles screened through a sieve of less than 500microns; and 20 Figure 7 is a table providing the code to understanding the XRF RESULTS, being test results determining the level of Cadmium found in Morrocan RPR used in fertilisers available in New Zealand, as relevant to the present invention. 25 Best Modes for Carrying Out the Invention With reference to the present invention there is provided a granule for a soil treatment system. It should be appreciated that the granule may be varyingly shaped and sized, and so forth as desired. 30 The granule is adapted to include various components desirable in the conditioning or treatment of soils. The granule preferably is comprised of components having specific particle size and surface area. Finely ground Reactive Phosphate Rock (RPR) is a said component, along with Muriate of Potash operating as a dispersant and binding agent. The RPR component preferably has improved "reactivity" and is preferably low in Cadmium. 35 The maximum concentration of cadmium allowable in phosphate fertilisers varies from country to-country. New Zealand has a voluntary limit of 120 md Cd / kg P 2 0. As mentioned previously, this level is not sustainable and will see an increase in cadmium in the environment, ,23 5 eventually to levels dangerous to human health. A range of phosphate rocks are available from around the world where the cadmium content varies dramatically. There are several sources of "medium" reactivity phosphate rocks with suitably low cadmium levels. Figures 1, 2 and 7 (with attached test results) demonstrates the maximum levels of Cadmium allowed in phosphate fertilisers in some countries around the world, the range of phosphate rocks from around the 1,0 world where the cadmium content varies dramatically, and provides the code to understanding XRF RESULTS after sampling fertilisers available for use in New Zealand. The granule is preferably able to easily disperse when applied to the soil and yet have sufficient compressive strength to ensure that the granule does not break-up during storage, transport and 15 application. The granule product includes any combination of the following features: a) Is a controlled release, long life granule formulated for a specific soil-type b) Is comprised of components having one or more of a preferred particle size, preferred 20 particle distribution, preferred particle surface area. c) Includes component(s) directed to a specific treatment, specific soil type, specific climatic conditions. d) Includes a component that facilitates dispersal of the granule in moisture/water, e) Includes a component that facilitates rapid release of at least one -other component 25 from the granule. f) Is uniform in size, g) Is dust free for improved handling, spreading, transportation and safety. h) Is colour coded to ensure the correct formulation is applied to the particular soil type. i) Is an improvement on products prone to leaching. 30 j) Granules are not easily separated during a mix. k) Fast acting for rapid results - such as rapid plant availability of nutrients. 1) A product which is adapted to address some environmental concerns. The fertiliser industry consumes about ninety percent of world phosphate rock production. In the 35 production of superphosphate, phosphate rocks are blended to produce a product with a total phosphate concentration of 15 - 16% which is then mixed with sulphuric acid to produce a final fertiliser product with around 9% P. 24 5 THE PROBLEM Superphosphate * Environmental problems e.g. phosphate run-off, sulphate leaching (taking valuable cations with it) and soil cadmium buildup. 10 * High capital equipment cost to manufacture * Low P concentration requiring more tones and more transport and storage costs * Fixed ratio of P:S Reactive Rock Phosphate * Minimal quick-release benefit in the soil. 15 0 Dust problems if ground finely enough to give good reactivity, * Cadmium. build-up. * Difficult to spread PRODUCT DESCRIPTION 20 The invention provides a granular fertiliser with the individual components finely ground to ensure a sustained release in the soil. Examples of some compositions based on the components on a percentage weight:weight basis is provided in Figure 3. However, it should be appreciated these examples are not to be seen as limiting the scope of this invention, but are rather provided 25 simply to offer some possible compositions within a range of suitable compositions falling within the scope of the present invention. Particles are sized to suit local conditions. Normally colder drier areas need finer particles. Particle size distribution in a granule of the present invention is provided in Figure 4. Both the phosphate and sulphur components provide a long-term residual effect in the soil. 30 Uniform granule size is a benefit in terms of transportation and application. The present invention provides a superphosphate replacement granule with the following characteristics., 0 Low cost (on an available P & S basis) * Low cadmium 35 0 Low acidity 25 5 * Controlled release " Wholly organic fertiliser " Not easily leachable from soil Muriate of Potash The Muriate of Potash (MOP) is used as a granule binding agent and is agronomically valuable in 10 its own right. MOP has not been previously been used as a binding agent for RPR. Run of mine MOP from high quality deposits may be used to ensure the acceptance of the product as organic. Binding agents other than MOP may be used, such as bentonite and molasses. 15 Fne Sulphu The fine elemental sulphur in the granules provides a form of faster acting sulphur which is readily plant available without the sulphate leaching problems associated with sulphate based fertilisers. In order to get a very fast sulphur response a minus 20 micron component is included in the 20 sulphur. RPR Acidulation The elemental sulphur has a superfine component (<10 micron). When the granule is wetted this superfine sulphur immediately comes into contact with the superfine reactive phosphate rock 25 (RPR) component. The RPR is then partially acidulated enabling more rapid reactivity in the soil. The RMS granules take in the region of seven hours to dissolve in water. During this time the fine ground sulphur and the fine ground RPR are in intimate contact (due to the high pressures applied during the granulation process). The moisture reacts with the fine sulphur to form sulphuric acid, which partially acidulates the fine RPR. 30 Organic Fertiliser This RPR, MOP and sulfur granular fertiliser is an organic replacement for superphosphate. All the components of this granular fertiliser have specific agronomic value. 26 5 Environmental Benefits RPR and elemental sulphur are not easily leached or susceptible to run-off from the soil, giving considerable environmental benefits. Reactive Rock PhosDhate 10 Fine grinding RPR has the following benefits e Reactivity is increased and the RPR becomes available to plants at a faster rate. e Low reactivity (and therefore cheaper) RPR may be used to produce a viable product. These lower quality RPRs (in terms if bulk reactivity) may also have the benefit of lower cadmium levels. (see below). 15 e Enables low reactivity phosphate rock with low cadmium levels to be used. * Enables the removal of the higher portion of high cadmium concentrated into the bottom end of the fines, These cadmium rich fines can be removed, treated and replaced back into the process, thus lowering the overall cadmium content. Fine grinding has been used as a method to increase the reactivity of phosphate rock. Grinding 20 provides 'fresh' particle surfaces, increases geometric surface area, and increases solubility measurements. The problem with finely ground rock phosphate is fine dust and the cost of fine grinding. Granulating the fine products mitigates the dust problem and enables accurate spreading. 25 Cadmium removal Cadmium is a naturally occurring, non-essential heavy meotal, which is present at low concentrations in air, water and soils, Cadmium is a potentially toxic heavy metal if it enters the food chain at high enough concentrations. Cadmium naturally occurs in phosphate rock, from which phosphate fertiliser is made. Phosphate 30 is essential for plant growth and maintaining New Zealand's agricultural productivity. Cadmium can accumulate in soils from ongoing phosphate-based fertiliser application. There is evidence that cadmium levels in New Zealand's soils are slowly increasing. 27 5 Phosphate based fertilisers are essential to the ongoing productivity of New Zealand agriculture. The fertiliser industry must therefore find ways to reduce the amount of cadmium entering the environment as it will continue to accumulate with continued phosphate fertiliser application. Ideally a phosphate fertiliser with less than 20mg cadmium / kg P205 (6ppm) should be used in New Zealand. 10 Most superphosphate fertilisers have at least 24ppmn cadmium content. Superphosphate fertiliser is at present the main (95%) source of new cadmium introduced to agricultural soils. The >24ppm cadmium content is well over the 6ppm level required to prevent accumulation in the environment. Currently it is difficult and expensive to remove the cadmium from superphosphate. 15 New Zealand has a voluntary limit of 120mg Cd / kg (ppm) P205, As mentioned above this level is not sustainable and will see an increase in cadmium in the environment, eventually to levels dangerous to human health. In some areas limits have been reached and Cadmium levels are dangerous to human health. A 2005 report produced by Environment Waikato states that offal from animals in the region 20 older than 2.5 years is not permitted to be sold for human consumption (there are no controls on animals being moved out of the region and sold elsewhere). This fact highlights the growing and serious concern presented by cadmium buildup in NZ soils. Environment Waikato holds farmers liable for any remedial costs to lower cadmium levels. Cadmium levels are required to be within Environment Waikato limits before subdivision approvals will be issued. While cadmium levels 25 may be reduced by very deep plowing on arable land this will not be possible on much of New Zealand's hill country. New regulations have or are likely to be put in place relating to this. Because the RPR is fine ground it can be easily classified into various sizes. The present invention has discovered that the finer sized RPR material contains a higher level. of cadmiun (see results Figure 4). 30 Cadmium generally exists in the softer portion of the phosphate rock and is therefore typically found in the finer portion of ground rock as impact mills such as hammermills and pinmills selectively grind softer material. A heat treatment process such as flash calcining is used to selectively remove the cadmium from the finer RPR. Flash calcining is a simple cost effective method of heating the fines to +9004C 35 and removing the cadmium in the gas flow. Flash calcining or methods that require the heated 5 particles to be carried in air may also have the effect of separating the cadmium from the RPR at lower than fuming temperatures. Particles in air travel slower than the air. The boiling point of cadmium is 765*C. The stripping action of the air is like wind over clothes on a clothesline, which will assist in removing the cadmium at lower temperatures. Heat treatment and removal of the cadmium results in a higher overall level of cadmium reduction than is currently possible 10 using conventional cadmium removal methods. In this way large cost savings can be made. By heat treating the RPR with a particle size less than 125 micron (approx.. 10% of the total), the total cadmium can be reduced by 16.6%. intimate particle contact 15 When elemental sulphur and RPR are inter-ground (under pressure) there is greater intimate contact between the particles. This results in a "bonding" together of the particles. As the inter grinding takes place the granule is also being compacted and this produces heat between 60 and 100*C. Sulphur mobilises at around 80"C and will possibly mobilise at a lower temperature under the high pressures used to form this granule. The mobilised sulfur will smear the fine RPR 20 particles thereby forming an extremely intimate contact. Biological oxidation of elemental sulphur (S) mixed and applied with RPR will increase dissolution of P from RPR to improve its effectiveness as a P fertiliser. In conventional fertilisers the sulphur and RPR do not remain in sufficient contact to benefit from this effect. 25 Customized g-ranules The amounts of phosphate and sulphur in the granule can be varied to suit the particular application. For example: A farm with optimum P levels will only require -sufficient P to maintain those levels but will still require S application At level suffgietu to remove the sulphur deficiency. Conversely some farms may require maintenance Phosphate (P) and very little 30 Sulphur (S). In another situation where P levels are too high the P levels can be slowly reduced by utilizing a granule with lower P reactivity. This will result in an overall lowering of cadmium introduced to agricultural systems. The granules can also be tailored to suit specific regions in terms of the particle size and reactivity. 35 29 s COST COMPARISONS Figure 5 is a cost comparison table showing the cost of use of Superphosphate based applications, versus the application of the RPR granule of the present invention. By way of explanation: Table Dairy Farm - Spring Application 10 SUPERPHOSPHATE BASED APPLICATION Superphosphate (250kg / ha), MOP (50kg /ha), Sulphur (30kg / ha) - with Maximum cadmium of 36mg/kg superphosphate. RPR GRANULE RPR (180kg /ha), MOP (50kg /ha), Sulphur (30kg/ha) is Dairy Farm - Autumn ApIlcation SUPERPHOSPHATE BASED APPLICATION Superphosphate (250kg / ha), MOP (50kg /ha) - with Maximum cadmium of 36mg / kg superphosphate. 20 RPR GRANULE RPR (180 kg /ha), MOP (50kg /ha) Sheep & Cattle Farm - Spring / Autumn Application SUPERPHOSPHA TE BASED APPLICA TION Superphosphate (250kg / ha), Sulphur (30kg / ha) - with Maximum cadmium of 36m& / kg 25 superphosphate. RPR GRANULE RPR (250 kg /ha), MOP (10kg /ha), Sulphur (30kg / ha). MANUFACTURE 30 Granule Size Smaller granule sizes are determined to be more effective as a resultant soil treatment feriiliser. Low Pressure Granulation It has been determined that in low pressure granulation the finer the particle size the greater the 35 granule strength. 30 5 Fineness & Reactiviy RPR reactivity is directly proportional to fineness. A relatively unreactive RPR which is finely ground can become sufficiently reactive so as to be useful as a fertiliser. For example, an RPR granule with 95% of particles passing 45 micron gives a higher citric acid 10 response. Surface Area & Reactivity The higher the surface area of fertiliser components the greater the reactivity. Surface area is generally proportional to fineness of the particles, but is also related to the structure of the 15 material. Figures 6c and 6d illustrate results of RPR particles screened through various sieves. Figure 6c is a table showing results of RPR particles screened through a sieve of less than Imm; and Figure 6d is a table showing results of RPR particles screened through a sieve of less than 500 microns. As 20 is illustrated in the results shown in Figures 6c and 6d, a greater percentage of fine particles (of 45 microns), is achieved using a sieve of 500 microns (when compared with a sieve of Imm) and is therefore preferable. TaIloring to Soil Type and Location 25 RPR particle size distribution is a critical factor determining whether a particular RPR can be used in given soil and climate conditions. An RPR granule consisting of a large proportion of less than 45 micron material as encompassed within the present invention, is able to be widely used in various conditions. For example: South Island soils and climate conditions. 30 A typical RPR fertiliser will take a substantially significant period for the majority of particles to react releasing phosphate into the soil. This finely ground and granulated RPR (95% < 45 micron) will effect a release of a significant proportion of phosphate within one year while retaining the benefits of low surface run-off. 35 Dispersion Rate Dispersion rate is an important factor in the viability and usefulness of fertiliser treatments. Figures 6a and 6b are the results of tests conducted to show the binding effect of the MOP and the resultant dissolution times dependent on the percentage MOP mixed with RPR and as a result of 31 5 the two granule formation processes exampled. Figure 6a illustrates the strength and dissolution rates of pressure formed RPR/MOP granules, while Figure 6b illustrates the granule strength and dissolution times of tumble agglomeration RPR/MOP granules. Such tests enable varying compositions to be developed dependent on the required rate of 10 dispersion required within specific soils and in different regions. Further, the tests indicate that by using pressure granulation smaller amounts of MOP can be used to achieve satisfactory granule strength. This is important as the MOP ratio to Phosphate is important. For example, excess MOP is not required to operate as a binder in order to achieve the 15 Phosphate required in a single dressing, As well as MOP, water operates as an effective binder during compaction of RPR granules. Water is the fluid component used in the tests as indicated in Figures 6a and 6b. 20 Although not exampled in this test, oil is also a component able to be used as the fluid portion of the granule formation. Of interest is the observation that a 1% vegetable oil component has been determined as effective in slowing down dispersion of RPR granules, enabling a more sustained release of the component into the soil. 25 When referring to the description of the present invention, it should also be understood that the term "comprise" where used herein is not to be considered to be used in a limiting sense. Accordingly, 'comprise' does not represent nor define an exclusive set of items, but includes the possibility of other components and items being added to the list. 30 This specification is also based on the understanding of the inventor regarding the prior art. The prior art description should not be regarded as being an authoritative disclosure of the true state of the prior art but rather as referring to considerations in and brought to the mind and attention of the inventor when developing this invention. 35 Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof, as defined in the appended claims, 32

Claims

1. A soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns; and said soil treatment composition characterised by said composition including at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR.

2. A soil treatment composition for use as a fertiliser as claimed in Claim I wherein said resultant composition of finely ground RPR and MOP is in granular form.

3. A soil treatment composition for use as a fertiliser, as claimed in Claim 2, wherein said MOP operates as any one of: a) A binding agent in the granule formation process. b) A dispersing agent following application of the granule on to or in to soil.

4. A soil treatment composition for use as a fertiliser, as claimed in Claim 3, wherein said soil treatment composition optionally includes at least one other binding agent including bentonite, molasses.

5. A soil treatment composition for use as a fertiliser, as claimed in Claim 4, wherein where the RPR in the soil treatment composition includes cadmium, the cadmium content is reduced by separation of at least some of the cadmium from the RPR by: a) the fine grinding of the RPR effecting separation of cadmium from the RPR to the fines of the ground RPR fraction. b) heat treatment of the RPR fines fraction to at least 900'C to remove the cadmium, said heating methods including flash calcining effecting removal of the cadmium in resultant gas/air flows.

6. A soil treatment composition for use as a fertiliser, as claimed in Claim 5, wherein thp finely ground RPR is obtained from original RPR sources having pre-determined cadmium levels less than 6ppm. 33

7. A soil treatment composition for use as a fertiliser as claimed in Claim 6, wherein the RPR component, when prepared for use with the- soil treatment composition, has a reactivity measured by a standard 2% citric test of said RPR of at least one of: a) soluble phosphate content greater than 30%, b) soluble phosphorus pentoxide percentage (% PzO 5 ) of around 9.4%.

8. A soil treatncnt composition for use as a fertiliser as claimed in Claim 7, wherein the reactivity of said RPR is improved by either or both: a) fine grinding of the RPR to include particles sizes of at least between 75 micron and less than 45 micron. b) compaction of the RPR.

9. A soil treatment composition for use as a fertilizer as claimed in Claim 8, wherein said composition also includes at least one of: a) finely ground elemental sulphur. b) a fluid, including water, oil. C) additional soil conditioning compounds and/or macro or micronutrients, including lime, trace elements.

10. A soil treatment composition for use as a fertiliser, as claimed in Claim 9, wherein said fertiliser composition includes on a percentage weight:weight basis: Muriate of Potash (MOP) 1-40 Reactive Rock Phosphate (RPR) 10-95 Sulphur (elemental) 0-40 Fluid 1-15 Other components including trace elements 1-10

11. A method of preparing a soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns; and said soil treatment composition characterised by said composition including 34 at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR, said method including the steps of: a) Inter-grinding pre-determined quantities of MOP and reactive rock phosphate (RPR) to produce a thorough mix having preferred particle sizes. b) Mixing a pre-determined quantity of fluid with the dry inter-ground components to improve the dispersion of MOP with the RPR.

12. A method of preparing a soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns; and said soil treatment composition characterised by said composition including at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR, said method including the steps of: a) Finely grinding a pre-determined quantity of the RPR to pre-determined particle sizes. b) Finely grinding a pre-deternined quantity of the MOP to pre-determined particle sizes. c) Mixing the RPR and MOP together. d) Mixing a pre-determined quantity of fluid with the dry inter-mixed components to improve the dispersion of MOP with the RPR.

13. A method of preparing a soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns; and said soil treatment composition characterised by said composition including at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR, said method including the steps of: a) Finely grinding a pre-determined quantity of the RPR to pre-determined particle sizes. b) Finely grinding a pre-determined quantity of the MOP to pre-determined particle sizes, b) Dispersing finely ground MOP in a pre-determined quantity of fluid. 35 c) Mixing the fluid/MOP mixture with the dry finely ground RPR.

14. A method of preparing a soil treatment composition for use as a fertiliser as claimed in any one of Claims 1 Ito 13, wherein the fluid includes water, oils.

15. A method of preparing a soil treatment composition for use as a fertiliser as claimed in Claim 14, wherein said composition also includes at least one of: a) finely ground elemental sulphur. b) additional soil conditioning compounds and/or macro or micronutrients, including lime, trace elements.

16. A granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, said granule comprised of a soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns; and said soil treatment composition characterised by said composition including at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR and a fluid to effect binding of the components, and said binding assisted via either or both agglomeration and the application of pressure in the formation of the granule.

17. A granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, said granulJe comprised of a soil treatment composition for use as a &rtiliser as claimed in Claim 16, wherein the fluid includes water, oil.

18. A granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, said granule comprised of as claimed in Claim 17, wherein said composition also includes at least one of a) finely ground elemental sulphur. b) additional soil conditioning compounds and/or macro or micronutrients, including lime, trace elements. 36

19. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 18, wherein said granule following application on to or in to soil, disperses at a pre-determined rate.

20. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 19, wherein said dispersion of the granule is effected by dispersion of the components of the granule at pre-determined rates and the strength of the granule.

21. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 20, wherein either or both the strength and dispersion rate of said prepared granule are affected by at least one of: a) Minimising the surface area of the granules by producing smooth surfaced granules. b) Minimising the bulk surface area by producing larger sized granules. c) 'Minimising-the amount of moisture present in the granule. d) Producing harder granules. e) Storage of prepared granules in preferred conditions for a preferred period of time. f) The components of the granule. g) Coating the granules.

22. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 21 wherein the MOP component of the granule: a) imparts strength to the fertiliser granule as a re-crystallised salt when it dries, b) is highly water-soluble and rapidly dissolves when in contact with moisture effecting dispersion of the components of the granules

23. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 22, wherein the said prepared granules are further hardened by at least one of: a) drying the granules. b) cooling the granules. c) the pelletising/granulation pressing technique employed. d) Post-production heating of the granules.

24. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 23, wherein the said granules are prepared by pelletising/granulation pressing techniques, including: 37 a) Formation of sheets of the soil treatment composition by means of a double-roll chinsolator applying up to 2000kg of pressure, whereby the pressed sheets are then broken up by means of a rotating finger type device to produce 0.2-8mm long granules with the desired strength and dispersion characteristics. b) Formation of pellets by means of a double-roll pressure pelletiser device applying up to 2000kg of pressure to produce granules 1-5mm long with the desired strength and dispersion characteristics.

25. A granule for use in soil treatment applications as a trtiliser as claimed in Claim 24, wherein said granules are hardened to achieve a pre-determined crush strength range from 1 - 10 kg.

26. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 25, wherein a quantity of the components of the granule is dispersed substantially continuously, once release is initiated, for the intended life of the granule.

27. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 26, wherein dispersion of said granules formed using low pressure compaction techniques is initiated in 2-3 seconds and for up to 10 hours, following exposure to moisture.

28. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 26, wherein dispersion of said granules formed using high pressure compaction techniques is initiated in less than 10 minutes and for up to 24 hours, following exposure to moisture.

29. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 26, wherein dispersion of said granules is delayed via coating, encapsulating or including within the granule a dissolvable or degradable material to effect release of the components over a period of time after introduction of the granule on to or into the soil.

30. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 29, wherein a said coating includes lime.

31. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 29, wherein a degradable material included in the granule to delay release of the components 38 over a period of time after introduction of the granule on to or into the soil, includes an oil, said oil slowing down dispersion of the RPR granules, enabling a more sustained release of the component into the soil.

32. A granule for use in soil treatment applications as a fertiliser, as claimed in Claim 31, wherein dispersion of said granules is provided via an initial boosted release rate of components from the granule following introduction of the granule on to or into the soil.

33. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 32, wherein for a granule including RPR, MOP and elemental sulphur, the inclusion of a minus 20 micron component included in the sulphur component effects a fast sulphur response following introduction of the granule on to or into the soil.

34. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 33, wherein for a granule including RPR, MOP and elemental sulphur a boosted release rate of the components of the granule is accomplished by providing a secondary component having different release rate characteristics than the first component

35. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 34, wherein for a granule including RPR, MOP and elemental sulphur, the elemental sulphur includes a superfine component (<10 micron), such that when the granule is wetted this superfine sulphur contacts the superfine reactive phosphate rock (RPR) component which is partially acidulated enabling more rapid reactivity in the soil.

36. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 35, wherein there is provided at least a second boosted release rate of components from the granule following introduction of the granule on to or into the soil.

37. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 36, wherein for a granule including RPR, MOP and elemental sulphur, biological oxidation of the finely ground elemental sulphur mixed and applied with the RPR effects boosted release and dissolution of Phosphate from the RPR to improve its effectiveness as, a Phosphate fertiliser.. 39

38, A granule for use in soil treatment applications as a fertiliser as claimed in Claim 37, wherein a boosted release rate of the components is accomplished by providing one component having an exposed surface area greater than other components) in the granule.

39. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 38, wherein for a granule including RPR, MOP and elemental sulphur, the elemental sulphur has an exposed surface area greater than the RPR particles resulting from smearing of the sulphur around the RPR particles due to heat production during high pressure formation of the granules.

40. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 39, wherein the granule, in its entirety, is substantially biodegradable within the soil treatment environment to which it. is introduced.

41. A granule for use in soil treatment applications as a fertiliser as claimed in Claim 40, wherein for a granule including RPR, MOP and elemental sulphur, the granule, in its entirety dissolves in water in the region of seven hours,

42. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, said granule comprised of a soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns: and said soil treatment composition characterised by said composition including at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR, said method including the steps of: a) Inter-grinding pre-determined quantities of MOP and reactive rock phosphate (RPR) to produce a thorough mix having preferred particle sizes. b) Mixing a pre-determined quantity of fluid with the dry inter-ground components to improve the dispersion of MOP with the RPR. c) Applying pressure to the mix to produce granules characterised by being dry, hard, stable, dust free. 40

43. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, said granule comprised of a soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns; and said soil treatment composition characterised by said composition including at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR, said method including the steps of: a) Finely grinding a pre-determined quantity of the RPR to pre-determined particle sizes. b) Finely grinding a pre-determined quantity of the MOP to pre-determined particle sizes. c) Mixing the RPR and MOP together. d) Mixing a pre-determined quantity of fluid with the dry inter-mixed components to improve the dispersion of MOP with the RPR. e) Applying pressure to the mix to produce granules characterised by being dry, hard, stable, dust free.

44, A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, said granule comprised of a soil treatment composition for use as a fertiliser, said composition including at least one soil treatment component, said soil treatment component including finely ground particulate reactive phosphate rock (RPR), said RPR being finely ground to include particles of less than 45 microns and particles of between 45 microns to 200 microns; and said soil treatment composition characterised by said composition including at least one other agent, said at least one other agent including Muriate of Potash (MOP) intimately combined with said RPR and a fluid to effect binding of the components, said method including the steps of: a) Finely grinding a pre-determined quantity of the RPR to pre-determined particle sizes. b) Finely grinding a pre-determined quantity of the MOP to pre-determined particle sizes, b) Dispersing finely ground MOP in a pre-determined quantity of fluid. c) Mixing the fluid/MOP mixture with the dry finely ground RPR. 41 d) Applying pressure to the combined mix to produce granules characterised by being dry, hard, stable, dust free.

45. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, as claimed in any one of Claims 42 to 44, wherein at least one of the active components also acts as dispersion and/or binding agent.

46. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, as claimed in Claim 45, wherein the fluid includes water, oils.

47. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, as claimed in Claim 46, wherein said granule composition also includes at least one of: a) felacy ground elemental sulphur. b) additional soil conditioning compounds and/or macro or micronutrients, including lime, trace elements.

48. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, as claimed in Claim 47, wherein the particulate components are mixed with at least one binding agent in an effective proportion to bind the particles in the form of granules having dimensions, weights and crush strengths appropriate for a mechanical application.

49. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil, as claimed in Claim 48, wherein the granules may be applied via aerial top-dressing, mechanical spreaders, manually.

50. A soil treatment composition for use as a fertiliser, as claimed in Claims 1 to 10 herein, with reference to the included examples and attached figures.

51. A method of preparing a soil treatment composition for use as a fertiliser as claimed in Claims 11 to 15 herein, with reference to the included examples and attached figures. 42

52. A granule for use in soil treatment applications as a fertiliser as claimed in Claims 16 to 41 herein, with reference to the included examples and attached figures.

53. A method of manufacturing a granule for use in soil treatment applications as a fertiliser when applied on to or in to soil as claimed in Claim 42 and 47 herein, with reference to the included examples and attached figures. 43