NZ561305A - Fertiliser additive for improving the agronomic performance of phosphate rock - Google Patents

Abstract

Provided is a formulation of phosphate rock for use as a phosphatic fertilizer consisting essentially of 80% phosphate rock, 13% elemental sulphur, 2% humate, 2% seaweed, 0.4-3% citric acid, 0.5-5% molasses and 0.5% hydrated sodium calcium borate hydroxide, where the combination provided an increased level of phosphate available to plants. Also provided is a method of improving phosphatic fertilizer by adding the formulation.

Description

561305 Patents Form No. 5 *10056632052* COa IPPC ref. HOI.00: n\ intellectual property OFFICE OF N.Z. 24 DEC 2008 received Patents Act 1953 Complete Specification We, Donald Edgar Henderson, a New Zealand citizen of 9 Gateway Gardens, Ely, Cambridgeshire, CB6 3DE, United Kingdom and Gregory Bruce Lupton, a New Zealand citizen of c/- 9 Gateway Gardens, Ely, Cambridgeshire, CB6 3DE, United Kingdom hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in the following statement: 1 561305 H01.003NZ FERTILISER ADDITIVE FOR IMPROVING THE AGRONOMIC PERFORMANCE OF PHOSPHATE ROCK TECHNICAL FIELD The invention relates to methods of improving the agronomic performance of phosphatic fertilizers and formulations of such fertilizers.

In particular, the invention relates to a combination of minor ingredients for use as a fertilizer additive in improving the agronomic performance of phosphatic fertilizers prepared from phosphate rock.

BACKGROUND ART Factors influencing the agronomic performance of phosphate rock applied directly to soil as a phosphatic fertilizer 20 include: (i) the physical and chemical properties of the phosphate rock; (ii) soil and climate; (iii) plant species and the cropping system; and (iv) the farming management practices. 2 /"r ' 2i°£C2m I ^£MJve-d/ 561305 H01.003NZ Known organic methods of improving the agronomic performance of these phosphatic fertilizers include: (i) composting organic waste with the phosphate rock 5 (phosphor-compost); (ii) inoculation of seeds or seedlings with phosphorous-solubilizing microorganisms (fungi, bacteria and Actinomycetes); and (iii). the inclusion in the cropping system of selected crop genotypes.

It is an object of the invention to provide an alternative 15 organic method of improving the agronomic performance of phosphate rock when used as phosphatic fertilizer.

It is an object of the invention to provide a formulation for use as a fertilizer additive to facilitate the preparation 20 from phosphate rock of phosphatic fertilizers with improved agronomic performance.

These objects are to be read disjunctively with the object of to at least provide a useful choice.

DISCLOSURE OF INVENTION In a first aspect the invention provides a formulation of phosphate rock for use as a phosphatic fertilizer comprising: • Phosphate rock (first major ingredient); • Elemental sulphur (second major ingredient); and • A combination of minor ingredients; intellectual PROPERTY OFFICE 9P Ni.Z. 3 • Is DEC 2008 RECEIVED 561305 HOI.003NZ where the combination of minor ingredients comprises humate, seaweed, a carbohydrate microbial energy source, a salt of borate and a weak organic acid.

Preferably, the major ingredients total at least 90 % (w/w) of the formulation of the phosphatic fertilizer. More preferably, the major ingredients total 90 to 95 % (w/w) of the formulation of the phosphatic fertilizer.

Preferably, the ratio of the first major ingredient to the second major ingredient on a weight-per-weight basis is in the range 4 to 9. More preferably, the ratio of the first major ingredient to the second major ingredient on a weight-per-15 weight basis is in the range 5 to 6.

Preferably, the minor ingredients total no more than 10 % (w/w) of the formulation of the phosphatic fertilizer. More preferably, the minor ingredients total 5 to 10 % (w/w) of the 20 formulation of the phosphatic fertilizer.

Preferably, the carbohydrate microbial energy source is selected from the group consisting of: monosccharide and disaccharide sugars. More preferably, the carbohydrate 25 microbial energy source is sucrose.

Preferably, the salt of borate is selected from the group consisting of: calcium borate/sodium borate (BORATE 46™); hydrated sodium calcium borate hydroxide (ULEXITE™). More 30 preferably, the salt of borate is hydrated sodium calcium borate hydroxide (ULEXITE™). 4 intellectual property i office OF fsi z 1 b DEC 2G RECEIVED 561305 H01.003NZ Preferably, the organic acid is selected from the group consisting of: weak organic acids. More preferably, the organic acid is citric acid.

The relative quantities and composition (specification) of the minor ingredients are selected to provide a formulation with the following characteristics: 1. A pH value in the range of 5.5 to 7.5 measured at 20 °C 10 for 1 part formulation in 2 parts distilled water; 2. An electrical conductivity (EC) value in the range 0.5 to 8 millisiemens (ms)/cm measured at 20 °C for 1 part formulation in 2 parts distilled water; and 3. A sodium ion concentration ( [Na+] ) value in the range 0.025 to 0.25 milliequivalents (meq)/100g.

Preferably, the pH value is in the range of 5.8 to 6.8 20 measured at 20 °C for 1 part formulation in 2 parts distilled water.

Preferably, the electrical conductivity (EC) value is in the range 0.5 to 2.2 millisiemens (ms)/cm measured at 20 °C for 1 25 part formulation in 2 parts distilled water.

Preferably, the solid form is a granulated solid form.

In a first embodiment of the first aspect the invention 30 provides a formulation of phosphate rock for use as a phosphatic fertilizer consisting of: 8 0 (±1.5) % phosphate rock intellectual property office of n.z. lit DEC2008 RECEIVED 561305 H01.003NZ 13 (±1.5) % elemental sulphur 2 % humate 2 % seaweed 0.4 to 3.0 % citric acid 0.5 to 5.0 % Molasses 0.5 % hydrated sodium calcium borate hydroxide In a second aspect the invention provides a method of improving the agronomic performance of a phosphatic fertilizer when applied to soil in solid form including the step of: • amending the phosphatic fertilizer with 5 to 10 % (w/w) of a combination of minor ingredients; where the phosphatic fertilizer consists of phosphate rock and elemental sulphur in a ratio in the range 4 to 9 (w/w) and the combination of minor ingredients comprises humate, seaweed, a carbohydrate microbial energy source, a salt of borate and a weak organic acid.

Preferably, the amending the phosphatic fertilizer provides a composition with the following characteristics: 1. A pH value in the range of 5.5 to 7.5 measured at 20 °C for 1 part of the formulation in 2 parts distilled water; 2. An electrical conductivity (EC) value in the range 0.5 to 8 millisiemens (ms)/cm measured at 20 °C for 1 part of the formulation in 2 parts distilled water; and »• 3. A sodium ion concentration ([Na+] ) value in the range 0.025 to 0.25 milliequivalents (meq)/100g of the formulation. intellectual PROPERTY OFFICE OF N.2. 6 Ik DEC 2068 RECEIVED 561305 H01.003NZ Preferably, the pH value is in the range of 5.8 to 6.8 measured at 20 °C for 1 part formulation in 2 parts distilled water.

Preferably, the electrical conductivity (EC) value is in the range 0.5 to 2.2 millisiemens (ms)/cm measured at 20 °C for 1 part formulation in 2 parts distilled water.

In a first embodiment of the second aspect the invention provides a method of improving the agronomic performance of a phosphatic fertilizer when applied to soil in solid form including the step of: • amending the fertilizer with 5 to 10 % (w/w) of a combination of minor ingredients; where the phosphatic fertilizer consists of 86 % (w/w) of phosphate rock and 14 % (w/w) elemental sulphur and the 20 combination of minor ingredients comprises: 2 % Humate 2 % Seaweed 0.4 to 3.0 % Citric acid 0.5 to 5.0 % Molasses 0.5 % hydrated sodium calcium borate hydroxide In a third aspect the invention provides a fertilizer additive for use in the formulation of phosphate rock for use as 25 phosphatic fertilizer in solid form comprising humate, seaweed, a carbohydrate microbial energy source, a salt of borate and a weak organic acid. intellectual PROPERTY OFFICE OF N Z. 14 DEC 2008 received 561305 H01.003NZ In a first embodiment of the third aspect the invention provides a fertilizer additive for use in the formulation of phosphate rock for use as phosphatic fertilizer in solid form consisting of: 2 % Humate; 2 % Seaweed; 0.4 to 3.0 % Citric acid; 0.5 to 5.0 % Molasses; 0.5 % hydrated sodium calcium borate hydroxide.

In a fourth aspect the invention provides a method of preparing a phosphatic fertilizer in granular form including the step of: • Mixing for a time sufficient to provide granules the following ingredients: 80 (±1.5) % Phosphate rock; 13 (±1.5) % Elemental sulphur; 2 % Humate; 2 % Seaweed; 0.4 to 3.0 % Citric acid; 0.5 to 5.0 % Molasses; and 0.5 % hydrated sodium calcium borate hydroxide.

In the description and claims of the specification the following acronyms, terms and phrases have the meaning provided: "Granules" means particles where 90% (w/w) of the particles 20 are 0.5 mm 0 to 0.6 mm 0 and "granular", "granulated" and "granulating" have corresponding meanings. intellectual property OFFtCE OF N.Z. 24 DEC 2C received 561305 H01.003NZ "Humate" means the salts of humic acid.

"Improving the agronomic performance" means providing an 5 increased level of phosphate available to plants as determined by the enhanced growth of plants grown in the soil to which the phosphatic fertilizer has been applied.

"RPR" means reactive phosphate rock (also known as "soft rock" 10 or "GAFSA RPR") where the apatite has a greater ability to dissolve in the soil and to rel-ease available phosphate to plants then unreactive phosphate rock.

"Salt of borate" means the salt formed between boric acid and 15 an alkali, such as an alkaline earth metal hydroxide.

"Seaweed" means multicellular algae, including kelp.

"SSP" means single super phosphate, an unreactive phosphate 20 rock to which sulphuric acid is added.

"Weak organic acid" means an organic acid for which the salt has a buffering capacity in moderate pH ranges, such as acetic acid, citric acid, formic acid and oxalic acid.

Ingredients are provided as powders where provided in solid form. Percentages and ratios are provided on a weight-per-weight (w/w) basis unless otherwise indicated. Statements relating to improving the agronomic performance of a 30 phosphatic fertilizer are relative to a phosphatic fertilizer of the same formulation, but excluding the minor ingredients. fNTELI^T^AL PRoeERTv OFFICE Of n z H DEC 2008 receive!") 561305 H01.003NZ Exemplary embodiments of the invention will now be described in detail with reference to the Figures of the accompanying drawings pages.

BRIEF DESCRIPTION OF FIGURES Figures 1A, IB and 1C - Comparison of the mean dry weight yields (g) (3 replicates, third monthly harvest) for treatments applied to Soil 1 (pH 5.4) at 100 kg/ha (1A) , 200 10 kg/ha (IB) and 400 kg/ha (1C).

Figures 2A, 2B and 2C - Comparison of the mean dry weight yields (g) (3 replicates, third monthly harvest) for treatments applied to Soil 2 (pH 6.0) at 100 kg/ha (2A), 200 15 kg/ha (2B) and 400 kg/ha (2C).

Figures 3A and 3B - Comparison of final pH of Soil 1 (3A) and Soil 2 (3B) at different application rates.

Figures 4A and 4B - Comparison of the mean dry weight yields (g) obtained when the treatment ESP2 is applied to Soil 1 (4A) or Soil 2 (4B) at different application rates (solid line) versus the application of treatment SSP at the equivalent of 400 kg/ha (broken line).

DETAILED DESCRIPTION Multiple factors influence the availability to plants of minerals applied to the soil as fertilizers. One of these 30 factors is soil type, or more particularly soil pH. However, modifying the pH of soil alters the biological activity associated with the indigenous soil micro flora and fauna. ^decm LREc e iv ed 561305 H01.003NZ The biological activity of the soil may be significantly inhibited by a modification of soil pH by less than one pH unit. Such changes in soil pH are common in soils that are treated with phosphatic fertilizers. Inhibition of the 5 biological activity of the soil is particularly acute where the phosphatic fertilizers are applied to acid soils.

It is known that the roots of selected crop genotypes may reduce the pH of the rhizosphere by exuding organic acids and 10 thereby increase the solubility and availability of sparingly soluble phosphates. This form of in situ acidulation increases the availability to the plant of the phosphate, but may be inhibited when traditional phosphatic fertilizers are applied to the soil due to the associated changes in soil pH.

Whilst not wishing to be bound by theory it is believed the formulations of the invention facilitate the preparation of phosphatic fertilizers with improved agronomic performance by promoting in situ acidulation. The phosphatic fertilizers 20 include phosphate rock and elemental sulphur as major ingredients and a selected combination of minor ingredients to which the promotion of in situ acidulation is attributed.

The relative quantities of the minor ingredients have been 25 selected to provide increased levels of phosphate available to plants when soils are amended with phosphatic fertilizer prepared from phosphate rock. The combination of minor ingredients typically includes humate, seaweed, a carbohydrate microbial energy source such as sucrose, a source of boron 30 such as hydrated sodium calcium borate hydroxide, and a weak organic acid such as citric acid. 11 intellectual PROPERTY OFFICE OF N.Z. 14 DEC 2008 RECEIVED 561305 H01.003NZ To be economically viable it should be recognized that where the carbohydrate energy source is sucrose it may be provided in a crude form such as molasses. Other crude forms of sugars may be used.

Whilst not wishing to be bound by theory it is believed the elemental sulphur in conjunction with the combination of minor ingredients promotes growth of soil microorganisms leading to the in situ acidulation. It is believed that it is this 10 microbially mediated in situ acidulation that results in the increased availability to plants of the phosphate from the phosphate rock.

The availability to plants of the phosphate released from the 15 phosphate rock by this microbial mediated in situ acidulation is believed to be further optimized through the inclusion in the preparation of the phosphatic fertilizer of the other minor ingredients.

The organic component humate, especially of the fulvic acid class, is believed to promote the availability to plants of the phosphate of the phosphate rock by adsorbing through its cation exchange capacity calcium, iron and aluminium ions in the vicinity of the in situ acidulation.

The organic component seaweed is believed to promote the availability to plants of the phosphate of the phosphate rock by adsorbing phosphate in a form readily assimilated via the rhizosphere. The seaweed is selected to have a sodium ion 30 concentration ([Na+] ) sufficiently low to provide a formulation with a [Na4] value in the range 0.025 to 0.25 milliequivalents (meq)/100g. 12 fnt^llsctual property offfce op n.z. 2 k DEC 2008 received 561305 H01.003NZ The inclusion of a weak organic acid such as citric acid is to moderate the pH value in the vicinity of the microbial mediated in situ acidulation.

The inclusion of a source of boron (as a salt of borate) is believed to increase the uptake of calcium ion via the rhizosphere.

The ratio of.minor ingredients in the combination is adjusted 10 to ensure a pH value in the range of 5.5 to 7.5 measured at 20 °C for 1 part formulation in 2 parts distilled water. This adjustment is made in anticipation of the soil type to which the phosphatic fertilizer is to be applied.

In the method of preparing a phosphatic fertilizer including the combination of minor ingredients, all the ingredients are used in a powdered (solid) form to ensure intimate mixing of the ingredients.

EXAMPLE Preparation of a phosphatic fertilizer The following ingredients were mixed in or delivered to a 25 mixing drum or pan granulator: 80 (±1) % Phosphate rock (Moroccan Buccra, 38% P2O5) ; 13 % Elemental sulphur (DURASUL™, 99%.S); and 7 (±1) % Combination of minor ingredients consisting of: 2 % Humate; 2 % Seaweed; 0.54, 0.70, 0.87 or 1.0 % Citric acid; ^EUECTUAL PROPERTY 13 OFFICE OF N.Z.

I b DEC 2006 received 561305 H01.003NZ 1.0 % Molasses; and Calcium borate/sodium borate 0.5 % (BORATE 4 6™).

All percentages are weight-per-weight (w/w) unless otherwise indicated. All ingredients were provided as powders.

The granulated mix was recovered from the granulator and dried (as required) to provide the formulations of phosphate rock for use as phosphatic fertilizer.

Assessing the agronomic performance of phosphate rock as a 10 phosphatic fertilizer The four formulations of untreated phosphate rock were applied as treatments using the following designations: ESP1 (1.0 % citric acid); ESP2 (0.87 % citric acid); ESP3 (0.70 % citric 15 acid); and ESP4 (0.54 % citric acid).

Treated phosphate rock SSP (Ballance AgriNutrients), RPR (Gafsa) and RPR amended with the combination of minor ingredients (designated TRPR) were also applied as treatments 20 for comparative purposes.

Soil (sandy loam from the Takaka region of New Zealand) was collected and the pH 5.4 (Soil 1) modified to 6.0 (Soil 2) by amendment with agricultural lime (CaC03> .

Ten rye-grass stolons were graded by weight and planted in each of 144 black polythene bags containing the soil (70 mm radius). The phosphatic fertilizer treatments were applied 3 days following planting. All treatments were applied at a INTELLECTUAL PROPERTY OFFfCE OF N.Z. 14 DEC 2008 RECEIVED 561305 H01.003NZ rate equivalent to 100 kg/ha (1.4 g/bag), 200 kg/ha (2.8 g/bag) or 400 kg/ha (5.6 g/bag).

Irrigation in addition to rainfall was applied via overhead sprinklers using deionised water and the weekly bag volumetric weight rebalanced by additional deionised water. The rye grass was harvested from treatment replicates at monthly intervals following treatment through the late spring/early summer. Fresh weight and dry weight determinations were made.

The dry weight increases for each treatment determined for the third monthly harvest are provided in Figures 1A, IB, 1C (Soil 1) and Figures 2A, 2B, 2C (Soil 2). Formulations of phosphate rock including the combination of minor ingredients were shown 15 to improve the agronomic performance of untreated phosphate rock to levels comparable with that of traditional treated phosphate rock (SSP, RPR).

The final pH of the soils following different application 20 rates of the treatments is provided in Figures 3A (Soil 1) and Figures 3B (Soil 2). Of significance is the ability to modify the pH of the soil by modifying the application rate of formulations of phosphate rock including the combination of minor ingredients (TRPR, ESP1, ESP2, ESP3 and ESP4). No such 25 modification of pH is observed with application of the remaining treatments.

The improvement in agronomic performance of phosphatic fertilizers prepared from phosphate rock provided by the use 30 of the combination of minor ingredients as a fertilizer additive is illustrated in Figures 4A and 4B. A mean dry weight yield equivalent to that provided by application of SSP to Soil 1 at a rate equivalent to 400 kg/ha is provided by |^<^VSFrtyI i 1 DEC 2008 RECEIVED 561305 H01.003NZ application of ESP2 at a rate equivalent to 127 kg/ha. A mean dry weight yield equivalent to that provided by application of SSP to Soil 2 at a rate equivalent to 400 kg/ha is provided by application of ESP2 at a rate equivalent to 173 kg/ha.

It is believed the observed improvement in agronomic performance of phosphatic fertilizers prepared from phosphate rock provided by the use of the combination of minor ingredients as a fertilizer additive will permit a reduction 10 in agricultural inputs and thereby provide a driver for the adoption of sustainable agricultural practice.

Although the invention has been described by way of exemplary embodiments it should be appreciated that variations and 15 modifications may be made with out departing from the scope of the invention. Furthermore where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred to in this specification. 16 intcllectual property i office of n.z. 2 4 DEC 2008 RECEIVED 561305 Received at IPONZ on 26 July 2010

Claims (4)

1. CLAIMS 1) A formulation of phosphate rock for use as a phosphatic fertilizer consisting of: 80 (± 1-5) % phosphate rock 13 (± 1.5) % elemental sulphur 2 % humate 2 % seaweed 0.4 to 3.0 % citric acid 0.5 to 5.0 % molasses 0.5 % hydrated sodium calcium borate hydroxide; and, where the combination provides an increased level of phosphate available to plants as determined by the enhanced growth of plants grown in the soil to which the phosphatic fertilizer has been applied.
2. 2) The formulation of claim 1 wherein the formulation has a pH value in the range of 5.5 to 7.5 measured at 20 °C for 1 part formulation in 2 parts distilled water.
3. 3) The formulation of claim 1 wherein the formulation has an electrical conductivity (EC) value in the range 0.5 to 8 millisiemens (ms)/cm measured at 2 0 °C for 1 part formulation in 2 parts distilled water.
4. 4) The formulation of claim 1 wherein the formulation has a sodium ion concentration ([Na+]) value in the range 0.025 to 0.25 milliequivalents (meq)/100g. 17 561305 Received at IPONZ on 26 July 2010 5) The formulation of claim 2 where the pH value is in the range 5.8 to 6.8 measured at 2 0 °C for 1 part formulation in 2 parts distilled water. 6) The formulation of claim 3 where the electrical conductivity (EC) value is in the range 0.5 to 2.2 millisiemens (ms)/cm measured at 2 0 °C for 1 part formulation in 2 parts distilled water. 7) The formulation of any one of the above claims where the solid form is a granulated solid form. 8) A method of improving the agronomic performance of a phosphatic fertilizer when applied to soil in solid form including the step of: • amending the fertilizer with 5 to 10 % (w/w) of a combination of minor ingredients; where the phosphatic fertilizer consists of 86 % (w/w) of phosphate rock and 14 % (w/w) elemental sulphur and the combination of minor ingredients comprises: 2 % humate 2 % seaweed 0.4 to 3.0 % citric acid 0.5 to 5.0 % molasses 0.5 % hydrated sodium calcium borate hydroxide; and, where the combination provides an increased level of phosphate available to plants as determined by the enhanced growth of plants grown in the soil to which the phosphatic fertilizer has been applied. 18 561305 Received at IPONZ on 26 July 2010 9) The method of claim 8 where amending the phosphatic fertilizer provides a composition with a pH value in the range of 5.5 to 7.5 measured at 2 0 °C for 1 part of the formulation in 2 parts distilled water. 10) The method of claim 8 where amending the phosphatic fertilizer provides a composition with an electrical conductivity (EC) value in the range 0.5 to 8 millisiemens (ms)/cm measured at 2 0 °C for 1 part of the formulation in 2 parts distilled water. 11) The method of claim 8 where amending the phosphatic fertilizer provides a composition with a sodium ion concentration ([Na+]) value in the range 0.025 to 0.25 milliequivalents (meq)/100g of the formulation. 12) The method of claim 9 where the pH value is in the range of 5.8 to 6.8 measured at 2 0 °C for 1 part formulation in 2 parts distilled water. 13) The method of claim 10 where the electrical conductivity (EC) value is in the range 0.5 to 2.2 millisiemens (ms) /cm measured at 20 °C for 1 part formulation in 2 parts distilled water. 14) A fertilizer additive for use in the formulation of phosphate rock for use as phosphatic fertilizer in solid form consisting of: 2 % humate; 2 % seaweed; 0.4 to 3.0 % citric acid; 0.5 to 5.0 % molasses; 0.5 % hydrated sodium calcium borate hydroxide; and, 19 561305 Received at IPONZ on 26 July 2010 where the combination provides an increased level of phosphate available to plants as determined by the enhanced growth of plants grown in the soil to which the phosphatic fertilizer has been applied. 15) A method of preparing a phosphatic fertilizer in granular form including the step of: • mixing for a time sufficient to provide granules the following ingredients: 80 (± 1.5) % phosphate rock; 13 (± 1.5) % elemental sulphur; 2 % humate; 2 % seaweed; 0.4 to 3.0 % citric acid; 0.5 to 5.0 % molasses; and 0.5 % hydrated sodium calcium borate hydroxide and, where the combination provides an increased level of phosphate available to plants as determined by the enhanced growth of plants grown in the soil to which the phosphatic fertilizer has been applied. 20