NZ551617A - Method of reducing loss of nitrogen from ammonium containig fertiliser - Google Patents

Abstract

Disclosed is a method of reducing loss of nitrogen from an ammonium containing product applied as a fertiliser, characterised by the step of mixing the ammonium containing product (such as urea) with at least one binding agent immediately prior to application of the resultant mixture to the area being fertilised, wherein the binding agent is capable of binding to a positively charges ammonium ion (such a lime, or a compound containing free ions of calcium or magnesium). The mixing of ammonium containing product with at least one binding agent may results in the formation of ammonium bicarbonate or ammonium carbamate. The method may also include a step of adding a catalyst containing a divalent metal cation.

Description

10055388546* ;Intellectual Property Office of N.Z. ;2 h JAN 2008 ;RECEIVED ;PATENTS FORM NO. 5 ;Fee No. 4: $250.00 ;PATENTS ACT 1953 COMPLETE SPECIFICATION ;After Provisional No: 551617 ;Dated: 24 November 2006 ;FERTILISER ;I Corey David Martin, a New Zealand citizen of 67 Taihape Road, Hastings, New Zealand hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed to be particularly described in and by the following statement: ;1 ;OurRef: 127599/3 VD ;FERTILISER ;TECHNICAL FIELD ;This invention relates to an improved fertiliser. ;BACKGROUND ART ;5 The agricultural industry is of significant importance due to its fundamental position in providing raw resources for human consumption as foodstuffs or in the textile industry, and increasingly in areas such as the production of bio-fuel. Therefore, it is important to maintain the productive capacity of land used in agriculture. To this end, it is well known to apply various forms of fertilizers to provide essential 10 nutrients necessary for the productive capacity of oil, and to improve natural processes of plants. ;Of these nutrients, nitrogen is of significant importance due to its critical role in plant growth. As such, there is a large number of different ways in which nitrogen is applied to agricultural land. Of these methods and forms, urea is widely used 15 not least because it has a comparatively high nitrogen content (approximately 46%). ;Urea has a number of significant advantages over other nitrogen containing fertilizers options used, these include the following: ;• It can be applied as either a solid or in solution; ;20 • It is not a fire or explosion hazard; ;• It has a higher nitrogen content than other try nitrogen forms, meaning overall shipping costs are reduced; ;2 ;Our Ref: 127599/3 VD ;• Its manufacture releases few pollutants into the environment; and ;• It can result in a crop yield increase on comparable levels to other forms of nitrogen. ;Once applied to an area, urea is converted to ammonium (NH4+) or ammonia 5 (NH3-) which are forms of nitrogen which are easily taken up by both plants and the soil, and therefore highly desired in a nitrogen fertiliser. ;However, use of urea is not perfect and there are a number of associated as a fertiliser. The most significant of these problems is the loss of nitrogen into the atmosphere through volatilisation. ;10 Volatilisation occurs when urea fertiliser is converted to ammonia gas. This process typically occurs in the first 48 hours after application. A wide range of variables affect the rate of volatilisation including soil temperature, moisture content and pH. ;The loss of nitrogen from urea also occurs via a number of other routes. One of 15 these is a decomposition reaction forming N02 (nitrous oxide) or NH3 (ammonia). These gases are then lost into the atmosphere. ;One common breakdown reaction of urea is catalysed by the enzyme urease present in organic residues. This occurs via the reaction: ;CO(NH2)2+ H20 + urease -»2NH3 + C02 ;20 In addition, urea which is applied to soil as fertiliser can be rapidly transformed by soil bacteria into ammonium salts and then into nitrate. Nitrate is highly mobile and moves easily with water through the soil, affecting groundwater and water quality. ;The formation of ammonia from urea leads to the surrounding area having a localised high pH and ammonia concentration. This area can be toxic for several ;3 Our Ref: 127599/3 VD ;hours, which may lead to the death of seeds or seedlings close by. In most soils this area is neutralized as the ammonia converts to ammonium. Therefore, although the application of urea initially results in a localised alkaline pH (due to formation of ammonia), the overall effect is to increase the acidity of the soil (due 5 to the formation of ammonium). It has been found that it is at least a couple of days at the minimum before plants are able to utilise the nitrogen in urea, during which time, nitrogen loss continues. ;To overcome this problem it is often recommended that urea is blended into the soil during tilling or via irrigation. Alternatively urea is applied during the time of 10 year when there are low moisture levels in the air and soil. However the efficaciousness of these methods are low. ;The loss of nitrogen from urea into the atmosphere decreases its cost and labour efficiency. It also decreases the positive effects of applied nitrogen content in the soil, and therefore limits the benefits to pasture or crop growth. ;15 Leaching of urea also occurs after application before ammonium ions can be bound to the soil or taken up by plants; again this decreases the efficiency of the fertiliser. ;Research has shown that one way of decreasing nitrogen losses through nitrogen volatilisation may be using a urease inhibitor or nitrogen inhibitors to slow or delay 20 hydrolysis. The inhibitors are coated onto the exterior of urea particles with the intention that they allow further time during which rain or irrigation can move the urea into the soil. ;The use of urease inhibitors however, significantly increases the cost and manufacturing required to produce the urea. This is not desirable for farmers, or 25 land owners who are regularly fertilising large blocks of land. ;4 ;Our Ref: 127599/3 VD ;Other agriculturally important nutrients applied to land include free ions such as calcium and/or magnesium, cadmium or phosphorus in the form of a phosphate fertiliser. ;Lime is a common fertilizer applied to pasture, and contains calcium carbonate, 5 CaC03 as the main constituent, but can also contain significant amounts of magnesium carbonate, MgC03. ;Calcium and magnesium ions are beneficial to soil as the positive ions are attracted to, and bind with the negative charges in clay particles neutralizing soil acidity and increasing soil pH. Lime does not move quickly though the soil, 10 therefore leaching is not usually a problem. ;It has been shown that for every 1 Kg of lime applied to land there is a potential liberation of 44 litres of C02 and this is therefore a potentially large source of greenhouse gases. It is thought that a high carbon content may help to inhibit nitrification. This is backed up by statements from New Zealand Fertiliser Use 15 Code of Practice 1998 to the effect that a high carbon to nitrogen ratio inhibits nitrification. However, applications of lime and urea based fertilisers to land are incompatiable with each other. For example, in an experiment undertaken by The University of Melbourne a nitrogen loss of 12.5% from urea was increased to a nitrogen loss of 22.5% when urea was applied to an area which had recently had 20 2.5 tonnes of lime per hectare applied. One suggestion to overcome this problem was to apply urea first, and then lime a week or more later. ;Therefore while both lime and urea provide benefits to the growing of pasture and other crops by providing a high nitrogen content and calcium or magnesium ions which neutralise soil acidity. The application of both within at least a reasonable 25 time frame has traditionally been detrimental to the quality of the land. ;5 ;Our Ref: 127599/3 VD ;In addition to the obvious consequences for the quality of the land, there is also a financial cost to the land owner. Having to organise for multiple applications over time periods significantly increases costs associated with improving the quality of productive land. These costs are significant, especially due to the increasing costs 5 of production squeezing profits, and increasing application costs due to rising fuel surcharges. ;It would therefore be beneficial if there was a fertiliser and method available which allowed for the application of urea in a form which minimises loss of nitrogen via volatilisation. ;10 All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a 15 number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. ;It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this 20 specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process. ;25 it is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice. ;6 ;Our Ref: 127599/3 VD ;Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. ;DISCLOSURE OF INVENTION ;According to one aspect of the present invention there is provided a method of 5 reducing loss of nitrogen from an ammonium containing product applied as a fertiliser, ;characterised by the step of mixing the ammonium containing product with at least one binding agent immediately prior to application of the resultant mixture to the area being fertilised. ;10 Throughout the specification the term "loss of nitrogen" should be understood as meaning leaching, volatisation, or other mechanism through which nitrogen may be lost from the area to which the resulting mixture may be applied. ;Throughout this specification the term 'ammonium containing product' should be taken to include any compound which incorporates, or can form ammonium on 15 reaction or breakdown. ;In a preferred embodiment the ammonium containing product is urea, and shall be referred to as such herein. ;However, this should not be seen as limiting, as other nitrogen or ammonium containing products may also be used with the present invention. For example 20 ammonium sulphate, ammonium nitrate potassium nitrate, di-ammonium phosphate ;Throughout this specification the term urea should be taken to include liquid or solid forms of urea with the chemical formulations: CON2H4 or (NH2)2CO, or compounds containing same. ;7 Our Ref: 127599/3 VD ;The fertilizer of the present invention has significant advantages over current ammonium containing fertilizers such as ammonium nitrate. This is due to the fertilizer of the present invention being cheaper and less explosive. The present invention also overcomes the problem associated with nitrate leaching from 5 fertilizer, and therefore loss from the environment of use. Nitrate leaching is a common problem when current ammonium fertilizers, such as ammonium nitrate are used. ;Throughout this specification the term 'binding agent' should be taken to include any chemical compound which is capable of binding to positively charged 10 ammonium ions and thereby decrease the volatilisation rate of same. ;However, the use of lime as the binding agent should not be seen as limiting. ;In a preferred embodiment the binding agent itself is beneficial as a fertilizer to either plants or soil. For example, in some circumstances, and depending on the soil type and condition phosphates and sulphates may also be desired to be 15 applied. In these situations, these may be used as binding agents with urea according to the present invention to allow an efficient multi-purpose fertilizer to be produced and applied. ;Therefore in preferred embodiments the binding agent also acts as a source of at least one compound or element beneficial to soil and/or plants besides the nitrogen 20 provided by urea. ;It should be appreciated that a combination of one of more binding agents may be utilised if it is desired to apply a combination of carbon, phosphate or sulphate to the area being fertilized. ;In a preferred embodiment the ratio of urea to binding agent may be 1:1. However 25 this should not be seen as limiting as a wide variety of ratios may be utilised with ;8 ;Our Ref: 127599/3 VD ;the present invention. ;In a preferred embodiment the binding agent may be lime, and shail be referred to as such herein. ;Throughout this specification the term lime should be taken to include ground-up 5 limestone rock, ground-up mark, or products of limestone which have been altered by burning or other processing to increase their water solubility. ;Lime is a common fertilizer applied to pasture, and contains calcium carbonate, CaC03 as the main constituent, but can also contain significant amounts of magnesium carbonate, MgC03. ;10 The use of lime in the present invention is contrary to expectations as discussed below. ;When lime is used as the binding agent, the calcium or magnesium in the lime acts to catalyse the reaction. It is anticipated that this is via the known reaction wherein the ammonia hydrogen ion undergoes replacement by metals. ;15 However, this should not be seen as limiting, as other metals may be utilised to catalyse the reaction. ;In a preferred embodiment the catalyst may be at least one divalent metal cation such as zinc, magnesium, calcium and copper. ;In alternative embodiments, where lime is not the binding agent, it may be 20 necessary to add these components, or any other suitable catalyst to the mixture. ;In this instance it is anticipated that any compound which is capable of forming an ammonium salt may be utilised as a catalyst. ;9 ;Our Ref: 127599/3 VD ;It should be appreciated that additional catalysts may also be utilised when lime is used as the binding agent, to ensure, or increase the rate or completeness of the reaction. ;In a preferred embodiment the calcium (or magnesium) carbonate in lime reacts 5 with urea to form ammonium bicarbonate, 2[NH4HC03] and ammonium carbamate, ;nh2co2nh4. ;In a preferred embodiment the reaction occurring may be as follows (to form ammonium bicarbonate): ;1. Urea (NH2)2CO + H20 NH4(OH) + NH3 (gas) + C02 ;10 2. 2[NH4(OH)J + 2[CaC03] 2[NH4HC03] + 2Ca + 02 ;However, this reaction should not be seen as limiting, as other reactions may also be taking place simultaneously, or in connection to the reaction. These may lead to alternative or additional products to ammonium bicarbonate and ammonium carbamate. ;15 The applicant's anticipate that the first reaction provided above: ;Urea (NH2)2CO + H20 NH4(OH) + NH3 (gas) + C02 ;May be occurring during the mixing step of producing the fertilizer of the present invention. The applicant's anticipate that the second reaction: 2[NH4(OH)] + 2[CaC03] 2[NH4HC03] + 2Ca + 02 may be the final product observed on the 20 plant/soil after application. ;However, this should not be seen as limiting, as both these reactions may be occurring during mixing, or throughout the mixing and application process. ;10 ;Our Ref: 127599/3 VD ;In a preferred embodiment, as well as providing carbonate to bind up ammonium, the use of lime also lead to a high concentration of Ca2+ and Mg2+ ions in the fertiliser. ;Calcium and magnesium ions are beneficial to soil as the positive ions are 5 attracted to and bind to the negative charges in clay particles neutralizing soil acidity and increasing soil pH. ;It is anticipated by the applicant's that Ca2+ and Mg2+ may be present as free ions. However, this should not be seen as limiting as they may also, or a portion of the ions may be present in a bound form. ;10 It should also be appreciated that when lime is used as the binding agent, it is not necessary to include an additional catalyst. ;In alternative embodiments other binding agents, incorporating a functional group capable of binding to ammonium, and which is not toxic or detrimental to pasture or soil environments may be utilised with the present invention. Examples of 15 alternative binding agents include sulphates, phosphates, or any other compound that can react to form an ammonium salt, for example: Cu(NH3)42+. ;It is well known that solutions of ammonium hydroxide (urea mixed with water) can dissolve reactive metal oxides and hydroxides, such as copper (ii) hydroxide to form ammine complexes. Solutions of ammonium hydroxide can also dissolve 20 aluminium and zinc with the liberation of H2 gas. ;For example the inventors have observed excellent results from very small quantities of urea and higher amounts of lime, or lime flour. ;In a preferred embodiment, the method may involve the step of adding a substance buffer to control the pH of the resultant mixture. ;11 ;Our Ref: 127599/3 VD ;In a particularly preferred embodiment, the pH buffer may be phosphoric acid. ;The operation of the pH buffer is as known to one skilled in the art and acts to alter the pH of the resultant mixture. ;However, the result of using a pH buffer are unexpected in that they reduce the 5 amount of ammonium in a gas form, which could be lost through volatisation or other mechanism such as leaching. ;The foregoing should not be seen as limiting, and alternate embodiments including those where no pH buffer is added, or where buffers other than phosphoric acid are envisaged. ;10 A further advantage of using a buffer such as phosphoric acid is that it dissolves some of the preferred embodiment of the binding agent (lime). This improves the solubility of calcium in the resultant mixture and improves its availability for uptake by plants. ;A range of examples of differing application rates and mixtures that the inventors 15 have found successful include the following: ;40kgs urea + 40kgs Lime flour. The inventors have found that this ratio provides a higher concentration of available nitrogen than 100 kilograms of solid urea applied using previously available techniques. ;25kgs urea + 10kgs salt(NaCI) + 36kgs Lime flour. The inventors have found that 20 this ratio provides a higher concentration of available ammonia than achieved by applying 60 kilograms of solid urea using known techniques. ;15kgs urea + 10kgs salt + Zinc, Copper, Cobalt, selenium+ 150kgs Lime flour ;20kgs urea + 10kgs Ammonium Sulphate + 20kgs Lime flour ;12 ;Our Ref: 127599/3 VD ;All mixed with approx 10% water by weight or volume. ;It should be appreciated that these volumes can be scaled up, maintaining the same ratios. It should be noted that the ratio of urea to binding agent of 1:10 also showed positive results. ;5 The ratio of urea to binding agent may be altered depending on the nutrient requirements of the soil. ;The unexpected results of the present invention are due to combination of lime and an ammonium containing product and that this is contrary to conventional wisdom or teachings in the art. For example, most instructions for the use of urea advise 10 that lime should not be added or administered at the same time as it increases the volatilisation of nitrogen as ammonia from urea. This is reflected in experiments where lime and urea have been simultaneously applied which have resulted in a very high level of nitrogen volatilisation from urea as ammonia. ;Similarly it has been shown that volatilization is reduced at cooler temperatures, as 15 shown in the following table (Overdahl et al), it is anticipated that this is relevant to both manufacture and after application of the fertilizer. ;Percent of surface-added urea volatilized as ammonia at different temperatures and days on the surface. ;Temperature (F) ;Days 45 degrees 60 degrees 75 degrees 90 degrees ;(% of added N volatilized) ;0 ;0 ;0 ;0 ;0 ;2 ;0 ;0 ;1 ;2 ;4 ;2 ;2 ;4 ;5 ;6 ;5 ;6 ;7 ;10 ;8 ;5 ;7 ;12 ;19 ;10 ;6 ;10 ;14 ;20 ;Data abstracted from curves in SSSP 24, pages 87-90, 1960. Urea was added on a silt loam soil at 100 lbs N. ;13 Our Ref: 127599/3 VD ;Applying both urea and lime to pasture and crops has previously resulted in an increase in volatilisation and therefore loss of nitrogen into the atmosphere. It was suggested that this could be overcome by applying urea first, followed by lime a week or so later. However, if large areas of land are to be fertilised, this doubles 5 the application costs of a top dressing plane, helicopter or truck and the increases in cost to the farmer or land owner is undesirable. ;The increase in volatilisation has therefore previously prevented a one application product containing the benefits of both urea and lime. ;Further, calcium and magnesium ions are beneficial to have in the fertiliser as they 10 neutralise soil acidity. Although a neutral to slightly acidic soil pH is desired to increase pasture or crop growth, higher soil pH levels have been found to increase nitrogen volatilisation, as shown in the following table (Overdahl et al): ;Percent of surface-added urea volatilized as ammonia at various soil pH levels and days on the surface. ;Soil pH ;Days 5.0 5.5 6.0 6.5 7.0 7.5 ;(% of added N volatilized) ;0 ;0 ;0 ;0 ;0 ;0 ;0 ;2 ;0 ;0 ;0 ;0 ;1 ;5 ;4 ;1 ;2 ;5 ;10 ;18 ;20 ;6 ;4 ;5 ;7 ;11 ;23 ;30 ;8 ;8 ;9 ;12 ;18 ;30 ;33 ;10 ;8 ;10 ;13 ;22 ;40 ;44 ;Data from SSSP 24, pages 87-90, 1960. Urea added on silt loam soil at 100 lb. N. ;It is believed that element availability, for example of nitrogen from ammonium is 15 greatest at a pH between 5.8 and 6.2, or slightly acidic. ;14 ;Our Ref: 127599/3 VD ;The use of lime as the binding agent therefore provides multiple effects; it binds to the ammonium to decrease volatilisation and increase nitrogen retention in the fertiliser, and uptake by both plants and the soil, and in addition provides the normal benefits of lime application. ;5 A further advantage of using lime is that the carbonate component increases the carbon content of the soil. This is also a significant advantage as it provides a high carbon to nitrogen ratio. A high carbon to nitrogen ratio decreases the conversion of nitrogen into nitrate forms which are easily lost through leaching. ;The applicant's believe that the high carbon to nitrogen also helps to inhibit ;10 nitrification, by encouraging heterotrophic bacteria whilst substantially reducing the activity of nitrifying bacteria. This is supported by work undertaken by Strauss and Lamberti which showed that when environment C:N ratios are high, heterotrophic bacteria are subject to a nitrogen limitation and will out compete nitrifying bacteria for available NH4+, thereby reducing nitrification rates. ;15 The inhibition of nitrifying bacteria also helps to ensure that the ammonium in the fertiliser of the present invention, either bonded to, or in suspension with calcium carbonate stays in the desired positive state instead of being converted into a nitrate form in nitrification processes from where it is quickly lost from the area being treated. ;20 The applicant has found that normal biological conversions of nitrogen and nitrification are significantly reduced when using the fertilizer as herein described. ;The present invention also reduces the occurrence of undesirable reactions such as the production of ammonium carbonate. Ammonium carbonate is a mixture of ammonium hydrogen carbonate and ammonium carbamate in varying proportions. ;25 Ammonium carbonate, is undesirable because under some conditions it has been shown that: Ammonia gas passed into a strong aqueous solution of the ;15 Our Ref: 127599/3 VD ;sesquicarbonate, converts it into normal ammonium carbonate (NH4)2HC03 which can be obtained in a crystalline condition from a solution prepared at 30 °C. On exposure to air, this releases ammonia and passes back to ammonium bicarbonate. ;5 In some situations this may not be the preferred products as the ammonium hydrogen carbonate may undergo the following breakdown reactions to form ammonia if the ammonium ion is not bound up by the soil or plant immediately. ;1. (NH4)2HC03 + 2H+ <-> 2NH4+ + C02 + H20 ;2. NH4+ + OH- «-> NH3 (gas) + H20 ;10 The end result of these reactions is that there is a substantially lower increase in soil (NH4OH) acidity due to the hydrogen being bound up as water. ;The inventors anticipate that the preferred ammonium bicarbonate does not undergo a similar reaction at the same rate. ;In a preferred embodiment the reaction may be controlled by manipulation of the 15 physical conditions, or the addition of additives to increase the formation of ammonium bicarbonate over ammonium carbonate. ;Therefore in a preferred embodiment the binding agent of the present invention acts to ensure that a high concentration of ammonium is present in the fertiliser and available to the soil and plants after administration. ;20 Throughout this specification the term 'immediately prior to application' should be taken as meaning at least on the same day. ;In one preferred embodiment the fertiliser of the present invention may be applied within approximately 30 minutes of mixing. ;16 ;Our Ref: 127599/3 VD ;In one preferred embodiment, the pH buffer is added to the fertiliser during the time period between mixing of at least one ammonium containing product and binding agent, and when the resultant mixture is applied to the area. ;Adding the buffer acts to control, and preferably lowers the pH to approximately 7 5 to 7.5 thereby limiting any possible volitisation of ammonia. ;It should be appreciated that application within approximately 30 minutes of mixing allows application while the temperature of the mixture is still low from the endothermic reaction which has occurred. This is beneficial as it prevents the requirement for additional cooling means, these can be expensive, and difficult to 10 transport between different job locations, ;However, this should not be seen as limiting as continued cooling after this time may also be utilised to keep the mixture at a low temperature. ;It should be appreciated that application while the fertilizer mixture is at a low temperature ensures that the ammonia is maintained in solution. ;15 In a preferred embodiment the fertiliser may also include water, or another solution or liquid. ;For example ammonium carbamate will dissolve in alcohol not water. ;Alternatively other fluids could be used, for example water soluble oil. ;A quantity of water is essential to the production of a fertilizer of the present 20 invention. The water acts to capture ammonia gas and ensure same is in the desired solution form. ;If water is not included, the dry mixture of urea and lime would lead to a high loss of nitrogen through volatilisation. This is due to the low moisture content present in lime, which initiates this reaction, but is not sufficient to keep the ammonia gas ;17 Our Ref: 127599/3 VD ;produced into solution. ;In a preferred embodiment water may also contribute to catalyse the reaction between urea and the binding agent. ;In a preferred embodiment the water also contributes to the delivery of the 5 fertiliser, which can be applied suspended in solution. ;In a preferred embodiment the volume of water used may be just sufficient to ensure that substantially all the urea and binding agent are dissolved or suspended in same. ;The use of a low volume of water reduces the fertilizer application time as only a 10 very small amount of water is required to reduce the solid urea into a liquid. Reducing the application time is highly desirable, especially where the fertilizer is being applied from a helicopter, or plane. In these instances the quicker the fertilizer can be applied, the more cost effective the process is to farmers and land owners. ;15 Yet a further advantage of using water is that it ensures that the ammonia is in an aqueous form. Therefore as the fertilizer is applied to the area, it is able to capture C02 from the air and assist in C02 sequestration. This is firstly an environmental benefit but also assists in providing a higher carbon to nitrogen ratio to inhibit nitrification. ;20 It should be appreciated that reference to the term fertilizer throughout this specification may refer to either the reactant mixture of urea and a binding agent, the reactants and products produced during the mixing and reaction process, and the final product of the reaction. ;In a preferred embodiment water may be present at an amount of approximately 25 10% the volume or weight of the mixture. ;18 Our Ref: 127599/3 VD ;The mixing of water, lime and urea leads to an exothermic reaction. ;The reaction leads to a significant decrease in temperature of the reactants and in some situations also the reaction vessel. ;The exothermic reaction leads to the loss of heat and a cold resultant fertilizer 5 mixture. ;Preliminary measurements indicate that the reaction leads to a decrease in reactant/product temperature to approximately 0 -2 °C. ;Therefore, if the fertilizer is applied while the fertilizer is a low temperature such as this, there is no requirement to further cool the fertilizer manually. It should be 10 appreciated that if the fertilizer is not to be applied for a significant amount of time, then the reaction vessel and fertilizer may be cooled to retain this low temperature. ;This lowered temperature also reduces volatilisation by slowing down the reaction rates and conversion back to urea or ammonia. ;Although at a low temperature, the mixture is still in a liquid form. ;15 Preferably the fertilizer of the present invention is sprayed onto the area to be fertilized while in a liquid form. ;However, this should not be seen as limiting. The inventor anticipates that it may be viable to dry the fertilizer product for storage and later application. ;In a preferred embodiment the fertilizer may be applied using any known technique 20 of spraying, this may include from a helicopter, a top dressing plane, from a truck, or by hand using a quad bike or backpack. ;In one particularly preferred embodiment the fertilizer may be applied using the equipment disclosed in New Zealand Patent Number 533182. ;19 ;Our Ref: 127599/3 VD ;In a preferred embodiment the fertilizer may be applied under high pressure. ;As ammonia gas liquefies readily under pressure, completing the mixing and/or application steps under pressure also act to decrease the loss of nitrogen through volatilisation. ;5 However, this should not be seen as limiting, as low pressure application techniques may also be utilised with the present invention. ;If an aerial application technique is applied, the applicants believe that the only period when volatilisation may occur is after the fertilizer is released from the helicopter or plane, and while it is falling to the ground. This is due to the 10 increased environmental temperature that the fertilizer is subjected to. ;However, as this time period is very short there is likely to be only minimal volatilisation, if any. ;It is anticipated that the fertilizer is only airborne for a few seconds before hitting 15 the ground/plants/soil. ;If a liquid solution of fertilizer is applied, this is in a liquid form when it reaches the ground. Some of the fertilizer will be absorbed directly into plants and soil. ;Once the fertiliser hits the soil in its liquid form some is absorbed by the soil or plants straight away however the rest crystallises as soon as the water evaporates, 20 this will depend on the temperature or humidity however it is only a short time period. It is believed by the applicants that the crystallised material form may be ammonium bi-carbonate. ;It is anticipated that this occurs within a matter of minutes from application. ;20 ;Our Ref: 127599/3 VD ;In a preferred embodiment the urea and binding agent may be in a solid or powdered form prior to mixing. However, this should not be seen as limiting, as these may be in solution prior to mixing. ;It should be appreciated that the smaller the particle size of the urea and binding 5 agent, the faster the breakdown in solution. Therefore in one preferred embodiment the urea and/or binding agent may be in a powdered form prior to mixing. ;In a preferred embodiment, any equipment capable of mixing may be utilised to mix the fertilizer of the present invention. ;10 In a preferred embodiment the equipment may allow mixture sufficient fertilizer of for the whole job. For example if eight tonnes of fertilizer is required to be applied to a farm then preferable the mixing equipment may be capable of mixing eight tonnes of fertilizer in one go. However, this should not be seen as limiting, as the fertilizer could also be mixed in smaller (or larger) batches. ;15 In a preferred embodiment application may be from a helicopter. Many helicopters are capable of carrying and applying approximately 700 kilograms of fertilizer per load. ;The applicant's have found that application of the fertilizer as herein described results in a dry matter of 30 to 40% over that observed when solid urea fertilizer is 20 applied. ;The fertiliser of the present invention provides a number of significant advantages, these include the following: ;• Nitrogen is applied to the ground as ammonium, which is positively charged. This significantly decreases loss of applied nitrogen from the 25 environment into the atmosphere or into water tables or reserves. This ;21 Our Ref: 127599/3 VD ;therefore decreases leaching and volatilisation, and increases the volume of nitrogen available to the soil or plants. ;Under standard practices of applying urea alone as a fertilizer, the reaction to form ammonia and then ammonium occurs after application. Due to the widely varying conditions of the environment and weather this can lead to substantial losses of nitrogen through leaching and volatilisation, which is undesirable. In this situation leaching and volatilisation can occur either before or after these reactions occur is there is excessive water or rainfall, this can also lead to ammonium bound components breaking down to its constituent parts. ;The applicants believe that biological conversions of nitrogen nitrification are reduced. This decreases conversion of nitrogen from its various forms to nitrates which are very soluble and quickly lost into the water flow. ;The combination of urea and lime increases the carbon content and results in a high carbon to nitrogen ration. This is desirable as it reduces conversion of urea or ammonium to nitrates. ;The combination of urea and lime also provides calcium and magnesium to the environment being fertilized; this is beneficial in reducing the soil acidify. ;The low temperature of the fertilizer after mixing, and quick application time, also act to reduce volatilisation. ;The method is quick and easy, and can easily be undertaken on site by the farmer, land owner, or person applying the fertilizer. ;The ability to incorporate a full spectrum nutrient blend while increasing reactivity of trace, or other elements. ;22 ;Our Ref: 127599/3 VD ;BRIEF DESCRIPTION OF DRAWINGS ;Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: ;5 Figure 1 shows an example of on-site mixing of the fertilizer of the present invention; ;Figure 2 shows an example of fertilizer components being transferred into the mixing tank; ;Figure 3 shows an example of mixing the fertilizer of the present invention; ;10 Figure 4 shows the fertilizer being transferred into a transport bucket; and ;Figure 5 shows an example of the fertilizer being transferred into an application bucket for application. ;BEST MODES FOR CARRYING OUT THE INVENTION ;The following is given by way of example only. ;15 Figure 1 shows an example of mixing the fertiliser of the present invention on site. A mixing tank (1) is shown on the back of a trailer bed (2) - this allows easy movement of the mixing station from one farm or site to another. ;The mixing tank (1) can be a range of sizes to accommodate different size loads, and includes a stirring paddle or mechanism (3). ;20 The stirrer for the mixing tank can be run by an on site generator (not shown in this figure) or other connection to a power source or battery. ;Also included is a control station (4), where a user can control the addition and ;23 ;Our Ref: 127599/3 VD ;mixing of the fertilizer components. ;Figure 2 shows an example of how the components are added to the mixing tank (5). This may be via bags of urea/binding agent (6) of the desired volume (or the addition of a portion of a bag). The bag may be lifted above the mixing tank (5) by 5 a crane (7) or other lifting device. The bag is positioned above an entry point (8) into the mixing tank, where a user (9) can control and ensure complete transfer of the component from the bag (6) to the mixing tank (5). ;Figure 3 shows an example of the mixing process within the mixing tank (10), wherein the fertilizer components and water (11) are thoroughly mixed by a stirring 10 mechanism (12). ;Figure 4 shows an example of how the fertilizer is transferred from the mixing tank (13) into a transfer tank (14) via a pipe (15). The transfer tank (14) can be moved to the application means via a tractor of front end loader (16). Alternatively the fertilizer may be mixed in a tank which is capable of being moved to the application 15 means, or mixed directly in the application bucket. ;Figure 5 shows one means of transferring the fertilizer of the present invention from a transfer tank (17) via a tractor, or front end loader (18) into an application bucket (19). The fertilizer is applied from the application bucket (15) by use of a helicopter (20). ;20 Methodology ;The general process for the production of ammonium based fertiliser of the present invention is as follows: ;1. Urea, or crushed urea is added to a sufficient volume of water to dissolve the volume of urea (and lime to be added later), ;24 ;Our Ref: 127599/3 VD ;2. The urea and water is vigorously mixed to form ammonium hydroxide. This is preferably carried out before the addition of lime or other binding agent. It is this reaction which leads to the significant decrease in temperature. ;3. Finely ground limestone is added at a 1:1, or other suitable ratio to the urea ;4. The reaction of urea, lime and water is exothermic and leads to a significant decrease in temperature of the mixture and mixing tank, ;5. The reaction leads to the formation of ammonium carbomate and ammonium bicarbonate, ;6. The decreased temperature of the suspended mixture and mixing tank ensure that the maximum amount of ammonia is converted to ammonium, ;7. The suspension is pumped under pressure, and delivered to the ground using a high pressure (or low pressure) delivery system, ;8. For maximum results the suspension is applied to the area to be fertilized within approximately 30 minutes of mixing. ;In an application, it may be necessary to include a ninth step which involves the addition of a buffering agent to reduce the pH of the water and resultant mixture. For example, dam water with a pH of 10 requires approximately 500mls of phosphoric acid per ton of urea to stabilize the resultant mixtures pH at 7.6. ;For example, one example of the present invention is that 1 tonne urea is crushed in a crusher (if required) into a reaction tank holding approximately 200 litres of water. The crushed urea and water is then mixed. Then 1 tonne of lime flour is slowly fed into the tank. ;25 ;Our Ref: 127599/3 VD ;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. ;26 ;Our Ref: 127599/3 VD *

Claims (8)

WHAT l/WE CLAIM IS:

1. A method of reducing loss of nitrogen from an ammonium containing product applied as a fertiliser, characterised by the step of mixing the ammonium containing product with at least one binding agent immediately prior to application of the resultant mixture to the area being fertilised.

2. The method according to claim 1, wherein the ammonium containing product is urea.

3. The method as claimed in either one of claims 1 or 2, wherein the binding agent is capable of forming an ammonium salt.

4. The method as claimed in any one of claims 1 - 3, wherein the binding agent is lime.

5. The method as claimed in any one of claims 1-4, wherein the binding agent contains calcium or magnesium.

6. The method as claimed in claim 5, wherein the calcium or magnesium are present as free ions.

7. The method as claimed in any one of claims 1-6, wherein the step of mixing the ammonium containing product with at least one binding agent results in the formation of ammonium bicarbonate.

8. The method as claimed in any one of claims 1-6, wherein the step of mixing the ammonium containing product with at least one binding agent results in the formation of ammonium carbamate. 27 Our Ref: 127599/3 VD *■ James & Weils Ref; 127589/60 CG 9, The method as claimed in any one of ciaims 1 - 8, wherein the ammonium containing product and binding agent have a ratio of 1:1 by weight or volume. 10, The method as claimed in any one of ciaims 1-9, characterised by the step of adding 8-catalyst 11, The method as claimed in claim 10, wherein the catalyst contains at ieast one divalent metal cation. 12, The method as claimed in any one of claims 1 -11, wherein the method includes the step of mixing a solvent with the combination of ammonium containing product and binding agent 13, The method as claimed in claim 12, wherein the solvent is water. 14, The method as claimed in either one of claims 12 or 13, wherein the solvent is approximately 10 % by weight or volume of the resultant mixture, 15, The method as claimed in any one of claims 1 13, wherein the mixture is applied within 30 minutes of mixing, 16, The method as claimed in any one of claims 1 to 15, wherein the method includes the step of adding a buffering agent 17, A method of reducing loss of nitrogen from an ammonium containing product applied as a fertiliser as substantially described herein with reference to the figures and specification. Future-N Ltd by iits authorised agents ■|hfTCU£CTUAL PROPERTY OFRCE OF HZ. 18 feb 2008 james & wells RECEIVED 28