WO2017194843A1

WO2017194843A1 - Fertilizer and method for its manufacture and use of fertilizer product

Info

Publication number: WO2017194843A1
Application number: PCT/FI2017/050368
Authority: WO
Inventors: Mikko RÄISÄNEN
Original assignee: Ecolan Oy
Priority date: 2016-05-13
Filing date: 2017-05-12
Publication date: 2017-11-16
Also published as: FI20165406A; FI127608B; EP3455193A4; EP3455193A1

Abstract

The disclosure relates to a fertilizer comprising a mixture of wood ash, nitrogen source and water in the form of granules. The invention further relates to the use of said fertilizer as a forest fertilizer, particularly as a fertilizer for peat forests and/or moorlands, and a process for the preparation of a fertilizer comprising a mixing step to form a mixture, a compacting and an after-treatment steps to obtain a fertilizer granules suitable for forest fertilization.

Description

FERTILIZER AND METHOD FOR ITS MANUFACTURE AND USE OF FERTILIZER PRODUCT

FIELD OF THE DISCLOSURE

The disclosure relates to fertilizers, and particularly to forest fertilizers comprising ash and nitrogen. The present disclosure further concerns a method for the manufacturing of new fertilizer as well as use of said new fertilizer in the fertilization of forests.

BACKGROUND OF THE DISCLOSURE

Nutrients are lost more effectively when harvesting forest energy compared to traditional harvesting. In several experiments, it has been found that the growth of the stock is deteriorating especially in the forest land when the nitrogen resources that can be used for the trees fall, as nitrogen deposit with rainfall is not enough to cover the deficit in some of the growth sites. Also, other nutrient deficiencies can be assumed to increase due to the "negative fertilization" that is meant nutrient removal during tree harvesting. According to studies the outgoing nutrients are especially magnesium and boron, which are also largely lost by traditional commercial timber harvestings, i.e. when harvesting only tree trunk, in relation to precipitation and availability from the forest soil. It has often been suggested that the lost nutrients should be restored back in the woods by ash fertilization. There is very little nitrogen in the ash, as it evaporates when burning. Also, the boric content of ash is too small in relation to other nutrients.

Ash fertilizers are used on peat soils throughout the year. Ash fertilization increases the tree growth in ditched peatlands, where minimum nutrients or nutrients, the lack of which weakens tree vitality, are, for example, phosphorus, potassium or magnesium. If ash is applied over mineral soil, it is generally not possible to achieve additional growth, as the growth limiting minimum nutrient in the moorlands is nitrogen. It has been shown that ash fertilizer alone does not produce enough nutrients for intensified tree growth, so therefore instead of ash fertilization it has been the custom to use mainly nitric fertilizers and nitrogen-containing salt and mineral based multi-nutrient fertilizers.

The use of fertilizers is also influenced by restrictions related to the spreading season/period. Main part of the nitrogen fertilizer used is saltpeter or ammonium nitrate. These ammonium nitrate -based fertilizers can be used during the growing season, preferably at the beginning of the growing season, to avoid leaching soluble nitrate into the waterways. To avoid nitrogen evaporation losses urea can only be used in autumn. Spreading of ash fertilizers can be done year-round.

Traditionally, nitrogen and ash fertilizers have been used to spread to forestland with different spreading equipment. Ash is applied nearly ten times the amount of urea, so different spreading equipments are required for spreading it/ash than for the spreading of nitrogen fertilizers. The amount of chemical fertilizers applied on woodland is between 300- 500 kg / hectare and the amount of ash applied is typically about 3000 to 6000 kg / hectare.

Helicopter applicates 150-700 kg / hectare spreading amounts with a centrifugal spreader and fertilizers applying at doses above 1500 kg / hectare are spread by simple weight/air flow using plough/duct spreaders. Separate fertilizers spreading/Spreading fertilizers separately? forms a significant part of the total cost of forest fertilization. Nitrogen- and ash fertilizers are also typically spread over the woodland at different seasons to minimize the loss of fertilizers caused with molten waters.

Because of the above-mentioned restrictions and the complexity of the operation, no ash fertilizers have been used in the mineral soils.

Many commercial nitrogen fertilizers contain ammonium nitrate because ammonium binds better to soil, and nitrate is in soluble form more rapidly exploitable by the trees. The use of ash in combination with ammonium nitrate is problematic as the ammonium part changes to ammonia and evaporates easily when the ammonium salt is dissolved under too alkaline conditions. The optimum application season for ammonium nitrate is during the growing season as the risk of nitrate leaching rises towards autumn.

The problem of urea as a nitrogen source is the evaporation of nitrogen in dry and hot weather, so the spreading season of urea is limited to autumn when the air temperature is sufficiently low and the humidity is sufficient. This has limited the use of urea as a source of nitrogen in fertilizations of the moorlands. Granulated ash fertilizers are typically produced by the so-called wet granulation technique where the moistened mass is granulated /in? a rotating drum and after that the wet granules are dried. However, wet granulation requires a lot of moisture and the final moisture content of the end product may be over 20% even after the pozzolanic reactions. In addition, the hardening of the final product takes about 7 to 14 days depending on the materials used.

Matrix peptization has also been used in the manufacture of fertilizers. However, it is not suitable for products containing plenty of/much ash because friction of ash particles is very high in matrix peptization, which requires more energy and wears the pelletizing equipment.

In dry granulation granules are formed without large amounts of liquid. Formation of granules without high water content requires compacting and densifying the powders. In this process, the powder particles are pressed together under high pressure. However, dry granulation with alkaline materials is not suitable for fertilizers containing nitrogen in the form of ammonium, because nitrogen in the form of ammonium evaporates in the granulation process.

WO2015132258A1 describes a method of adding micronutrients into the outer shell of the urea-based particles used in the fertilizer and the method involves the application of liquid concentrated mineral acid to the urea-based particles to form a double-layer of salt on the surface of the urea-based particles. The method uses strong mineral acids such as sulfur, nitrogen, phosphorus and/or boric acid and the amount of acid contributes substantially to the dustiness properties of the product. Drying of the product is also an important feature of this process since the reaction between acid and base powder produces water. In addition, the method is rather complex and multi-stage, and there is no ash derived from natural sources such as forest or field biomass. Further, said publication does not solve the problem related to the volatility of nitrogen.

Fl 123980 describes a method for handling side streams and waste liquids in the paper and pulp industry, and a fertilizer manufactured from refined ash free from heavy metals obtained from combustion of the aforementioned. This patent publication neither contains any solution for the spreading of fertilizers and/or the reduction of transport costs and quantities, nor the reduction of nitrogen evaporation.

US4571254 describes a method of making a fertilizer from wood ash and coniferous wood or other wood waste. With the method, it is possible to produce fertilizer containing peat, urea, ash and bark, whose nutrient content, however, remains relatively low due to peat and bark contained in the fertilizer. The application volume of this product per hectare is easily increased and the transport and distribution costs of the fertilizer and the time spent on the spreading are considerable. However, the method can be used to produce fertilizers for countries where there is no humus or for landscaping where low nitrogen solubility is generally of interest.

There are some drawbacks on the fertilizers on the market. Nitrogen and ash fertilizers cannot be applied simultaneously to the same site and solely by using nitrogen fertilizers all the nutrients that are removed with the harvesting of the trees cannot be replaced. In addition, to avoid losses due to evaporation, the use of nitrogen fertilizers is limited in time to summer with ammonium nitrate -based fertilizers and to autumn with urea-based fertilizers. Based on the above and current knowledge it can be stated that an efficient and time-saving process and a fertilizer product that solves the problem of nitrogen evaporation is clearly needed.

BRIEF DESCRIPTION OF THE DISCLOSURE

An object of the present disclosure is to provide a solution to avoid the disadvantages of the known technology, and which makes it possible to produce nitrogen and wood ash containing nutrient-rich fertilizer for use in forest land fertilization. Further, an object of the present disclosure is to provide a solution, that allows fertilization of the forested land to be cost-effective, in a simple and time-saving way.

The invention is based on the basic idea that it is possible to produce a nutrient-rich forest fertilizer, containing wood ash and nitrogen source, by dry granulation without peat, wood bark or other binder, traditionally added to improve nutrient storage and/or stability of the fertilizer composition. By using ashes in place of phosphorous minerals or salts traditionally used as raw materials for fertilizers, fertilizer can be produced from waste ash, and it can be used to restore removed nutrients from the forest without the use of industrially produced raw materials.

The invention is directed to a fertilizer comprising a mixture of wood ash, nitrogen source and water, the fertilizer is in the form of a granule, the granule has a pH of 10 to 13.5 and the crushing strength of the granule is 1 .5 to 6 kg.

The invention is also directed to a process for preparing a fertilizer, which method comprises the steps of administering wood ash and nitrogen source to the mixer, mixing, whereby a mixture is obtained, the mixture is compacted and post-processed to a granule size between 1 -25 mm.

The product produced by the process of the invention is stable and nutrient storage capacity of the product is optimal for use in the forest soil fertilization. The invention is directed to the use of fertilizer as a forest fertilizer. More specifically, the product according to the invention is characterized by what is stated in the characterizing part of the appended independent claim 1 .

The use according to the invention is characterized by what is set forth below in the characterizing part of the dependent claim 14.

The method according to the invention is characterized by what is stated in the characterizing part of the appended dependent claim 15.

DETAILED DESCRIPTION OF THE DISCLOSURE

The invention relates to a fertilizer comprising a mixture of wood ash, nitrogen source and water, the fertilizer is in the form of a granule, the granule has a pH of 10 to 13.5 and the crushing strength of the granule is from 1 .5 to 6 kg.

The invention is directed specifically to fertilizer for use in forest soil fertilization, which fertilizer comprises nitrogen source and wood ash, and the fertilizer comprises granules of which the crushing strength is between 1 .5 to 6 kg, the water content is between 7 and 18 %, the pH is between 10 and 13.5, the bulk density is between 950-1 150 kg/m³ and the average particle size is between 1 and 25 mm.

Fertilizer refers here to a fertilizer product.

According to a preferred embodiment, the water content of the granules is between 10 and 12 %.

According to a preferred embodiment, the granules have a pH between 12 and 13.

According to a preferred embodiment, the bulk density of the granules is between 950 and 1 150 kg/m³. According to a preferred embodiment, the average particle size of the granules is between 2 and 12 mm.

In this application, wood ash refers to ashes derived from combustion of forest biomass, arable biomass, wood-based sludges from forest industry processes, or combustion of mixtures of the foregoing, or combustion of mixtures thereof with peat. The ash may be waste ash generated by waste incineration or by waste co-incineration at power plants. Ash may also be the ashes generated by waste burning power plants through a recovery operation, such as thermal cleaning process. Preferably, the ash is generated by combustion having as the main combustion raw material forest biomasses such as wood material, bark, stumps, needles/leaves, in an amount of 30 to 100%, particularly preferably 60 to 80%. The ash thus obtained is referred to as wood ash. A significantly more versatile micro-nutrient dose is obtained from wood ash compared to chemical fertilizers.

In this application, the nitrogen source is selected from urea, methylene urea, formaldehyde urea, isobutylidene diurea, and mixtures thereof. The source of nitrogen can be granulated or soluble. Preferably, urea is used which is granulated or granular urea.

The pH of the finished fertilizer according to the invention is from 1 1 to 13.5, preferably from 12 to 13.

The crushing strength of the finished fertilizer according to the invention ranges from 1 .5 to 6 kg, preferably the crushing strength is between 2 and 5.5 kg.

The finished fertilizer according to the invention has a water content in the range of 7 and 18%, preferably water content of 10 to 12%.

The bulk density of the finished fertilizer according to the invention is between 950 and 1 150 kg/m³, preferably 1050 kg/m³. The average particle size of the finished fertilizer according to the invention is in the range of 1 to 25 mm, preferably 2 to 12 mm.

The water solubility of the finished fertilizer according to the invention is in the range of 15 to 20%, preferably 18 to 19% by weight of the dry matter.

According to another preferred embodiment, in addition to the nitrogen source and the ash, an additive selected from boron, potassium and phosphorus source and mixtures thereof can be added to the granule.

In a preferred embodiment, the fertilizer has an ash content of 60 to 90% by weight, preferably 65 to 85% by weight.

In a preferred embodiment, the fertilizer has a nitrogen content of 1 .4 to 10% by weight, preferably 2 to 5% by weight.

In this application, the potassium source is selected from potassium chloride, potassium sulphate, biotite, jarosite and mixtures thereof, preferably potassium source is potassium chloride. The potassium content of the fertilizer may be from 1 to 10% by weight, preferably from 1 .4 to 6.5% by weight. The fertilizer may contain from 0 to 30% of the added potassium source, preferably from 0 to 5% by weight, equivalent to from 0 to 5% by weight, preferably from 1 to 5% by weight, of the added potassium expressed as pure potassium. Some of the potassium contained in the fertilizer may come from ashes used as ingredients.

In this application, the phosphorous source is selected from apatite, superphosphate, phosphoric acid, sludge ashes and mixtures thereof, preferably the phosphorus source is superphosphate. Superphosphate refers to calcium dihydrogen phosphate or a mixture of calcium dihydrogen phosphate and calcium sulfate. The phosphorus content of the fertilizer may be from 0.5 to 4% by weight, preferably from 0.7 to 2.6% by weight. The fertilizer may contain from 0 to 6.5 wt.%, Preferably from 0.5 to 5 wt.% of added phosphorus source, which corresponds to from 0 to 2.6 wt.%, Preferably from 0 to 1 .3 wt.% of added phosphorus calculated as pure phosphorus. Some of the phosphorus contained in the fertilizer can be derived from the ashes used as the constituent material, so the amount of phosphorous source can be adjusted by the amount of phosphorus contained in the ash.

In this application, the boron source is selected from boric acid, sodium borate, ulexite, colemanite and mixtures thereof, preferably boron source is sodium borate. The fertilizer may have a boron content of from 0.01 to 1 wt.%, preferably the boron content may be from 0.01 to 0.5 wt.%. The fertilizer may contain from 0 to 2.5 wt.%, preferably from 0.2 to 1 wt.% of boron source, corresponding to from 0 to 0.3 wt.% of the added boron element calculated as boron.

According to a preferred embodiment, the solubility of nitrogen in fertilizer granule can be adjusted by adjusting the ratios of urea, methylene urea and/or formaldehyde urea. In one embodiment, the fertilizer granule intended for spreading after intermediate felling or winter spreading may contain 100% of formaldehyde urea from the nitrogen source.

In another embodiment, a fertilizer granule containing either urea or methylene urea or urea and methylene urea in the ratio of from 1 to 99%: from 99 to 1 %, preferably 50%: 50%, may be applied to young forests and/or peaty forest soils. In a further embodiment, for moorlands in the spring and fall, when humidity is sufficient, can be spread a fertilizer granule, wherein the nitrogen source is 100% urea.

Furthermore, it was found that when using methylene urea and formaldehyde urea, the already slowly water-soluble methylene urea grades will become more slowly water- soluble.

Further, as one of the advantages of the invention, it can be stated that in a preferred embodiment, only a small amount of added phosphorus and/or boron source is used to produce the product, because for example from 40 to 70% of the boron contained in the product and from 60 to 100% of the phosphorus and potassium can come with the ashes used to produce the product. This is a clear advantage given that boron and phosphorus are classified as critical elements that are scarcely available. The use of methylene urea with ash is based on the idea that the amide nitrogen cannot be converted into ammonium/ammonia under alkaline conditions. Instead, the ammonium nitrogen converts under alkaline conditions into ammonia and evaporates as a gas. The solubility of nitrogen can be slowed down, for example, by using urea formaldehyde, whereby dissolution takes place over a longer period of time, and alkaline ash blocks the degradation of already slowly dissoluble urea formaldehyde and nitrogen dissolution. The methylene urea (MU) contained in the fertilizers breaks down in the wild before enzymatic dissolution as a result of microbial activity into ammonium ions, formaldehyde and urea. Provided methylene urea is in an alkaline product such as with ash as hard granules, microbial activity is inhibited and already slowly water-soluble or more polymerized insoluble urea formaldehyde grades become even more slowly soluble.

Additionally, if the product is applied to a molten soil, as the urea is slowly dissolved from the granule it binds tightly into the humus layer of the woodland, thus avoiding the risk of leaching. By adjusting the urea/formaldehyde urea ratio it is possible to adjust the solubility of nitrogen into an even more slowly soluble form.

The invention also relates to a method for preparing a fertilizer where wood ash and nitrogen source are administered to a mixer, mixed to form a mixture, the mixture is compacted and after-treated to a granule size between 1 to 25 mm.

The mixture comprises water which may be added together with other ingredients into the stirrer. Alternatively, or additionally, the obtained mixture may contain water originated from the other ingredients such as from the nitrogen source.

In particular, the method of the invention comprises the steps of administering from 60 to 90% by weight of wood ash and from 2 to 32% by weight of nitrogen source, from 0 to 18% by weight of water, from 0 to 6.5% by weight of a phosphorus source, from 0 to 30% by weight of potassium source and from 0 to 2.5% by weight of boron source into the stirrer and stirring for 2 to 5 min to obtain a mixture, compacting and after-treating to a granule size between 1 to 25 mm. According to one embodiment, the method for preparing a fertilizer according to the invention comprises steps of administering from 60 to 90% by weight of wood ash and from 2 to 32% by weight of a nitrogen source calculated as a nitrogen compound, from 0 to 18% by weight of water, from 0 to 6% by weight of phosphorous source, from 0 to 30% by weight of potassium, from 0 to 2.5% by weight of boron source into the mixer and mixing for 2 to 5 min to give a mixture. The mixture is then pressed with clamping screws, thus forming a plate between the compactor rolling rolls, which plate breaks down when cast from rolls into pieces which are then after-treated to a granule size between 1 to 25 mm.

Preferably from 65 to 85% by weight of ash and from 3 to 12% by weight of nitrogen source are dispensed into the mixer.

Preferably, the pieces are after-treated to a granule size between 2 to 12 mm.

Optionally, in addition to the ash and nitrogen sources, an additive is administered which additive is selected from the potassium source, phosphorus source, boron source, and mixtures thereof. The amount of additives is from 0 to 30 wt-% of potassium source, from 0 to 6.5 wt-% of phosphorous source, from 0 to 2.5 wt-% of boron source, and corresponding to the added elements calculated as potassium, phosphorus and boron: potassium from 0 to 5 wt-%, phosphorus from 0 to 2.6 wt-% and boron from 0 to 0.3 wt-%.

The ash, nitrogen source and optional additives can be dispensed, for example, from dispensing funnels with screw and/or belt conveyors to a mixer. Alternatively or additionally, powdered raw materials can be dispensed from silos to the mixer and moist materials as well as the filtrate can be dispensed from the dispensing funnels.

Filtrate means restoring this undersized fraction, i.e. less than 1 mm, from the after- treatment back to the mixing step. Compacting is performed with a compactor. Optionally, the mixture is pressed with sealing rolls prior to the compactor, for example at a mass flow rate with rotating sealing rolls, where the sealing rolls are weighing from 100 to 500 kg in the pre-compacting thus performed. In the compactor, the mixture is compressed with compression screws between the compacting rollers and as the screws are pressing the mass between the rolls of steel, the rotation of the rolls and the pressure and the compacting of the screws cause bar pressure between the rolls of between 30 and 50 bar, preferably 35 to 45 bar. By means of pressure, a plate is created between the rollers. The compression force of the press screws is about 2 to 15 kN/cm.

In after-treatment, the grain size of the product is adjusted, for example, by sieving to fit, the under-size is returned to the process and the oversized is crushed, for example, to crushed beam or crush obtained by roll crusher, and returned to the sieve. The after- treatment step may include a sieving step for sieving granules and for obtaining an accept, an under-size rejection and an over-sized rejection, a step of returning the undersized reject back to the mixing step, and a step for crushing and restoring the oversized reject to the sieving stage.

The fertilizer product has an average grain size of about 1 to 25 mm, preferably from 2 to 12 mm.

The method for preparing a fertilizer according to the invention is time-saving, cost- effective and simple compared to traditional wet granulation processes. By dry granulation comprising mixing, compacting and post-treatment, it is possible to treat ashes with 7 to 18% water content and the resulting product is drier. When the ash oxides, mainly calcium, are hydrated heat is produced that draws the granular product to 10 to 12% water content. The hardening time of the granules is about 2 days depending on the reactivity of the ashes used. The amount of soluble organic matter in the ash does not interfere with production as much as, for example, wet granulation.

It is also significant that the cured granules do not dissolve or disintegrate when immersed in water, and the solid state of fertilizer compositions remain in the soil for several years.

In this application, the mixer means a vertical-shaft mixer, a horizontal-shaft mixer, screw conveyor or a screw mixer. Any device/apparatus selected by the person skilled in the art and suitable for mixing may also be applied as a mixer. In a preferred embodiment of the invention, the ingredients are transferred with a pneumatic conveyor to the mixer. In one embodiment of the invention, the plate formed in the compactor can be broken to granules by dropping. According to yet another embodiment, the plate formed in the compactor can be broken by a roller crusher installed directly after the compactor. In one embodiment, roller wheels are mounted against the compactor roll to split the plate. In yet another embodiment, the plate can be disrupted by a compactor roll shaped as "pre- granules".

The invention and its other objects and advantages are described in more detail in the following exemplary presentation, referring to the accompanying Figure 1 showing a diagram of the manufacturing method of the product of the invention and wherein the corresponding reference numerals in Figure 1 refer to corresponding features. In Figure 1 , the method steps of the invention are as follows:

10) the mixing step of the weighed or by volume dispensed raw-materials, and to form a mixture,

20) optionally, pre-compacting the mixture with the sealing roll,

30) a plate-forming step for forming a plate from the mixture,

40) a disintegration step for disintegrating the plate and forming granules 50) after-treatment step of the granules for after-treating the granules.

Figure 1 shows a schematic illustration of the manufacturing method of a product according to the invention.

A source of nitrogen (1 ), preferably urea and/or methylene urea, and/or urea formaldehyde and/or isobutylidene diurea, a phosphorus source (2), preferably apatite and/or superphosphate, potassium source (3), preferably potassium chloride and/or potassium sulphate, ash (4), boron source (5) and water (6) are weighed and/or dispensed according to volume and mixed in a mixing step with a mixer (10) (for example, a vertical-shaft mixer or horizontal axis mixer) to give a mixture (1 1 ). Optionally, the mixture can be pre- compacted with freely rotating sealing rollers (20) and the pre-compacted mixture (21 ) can be guided to the compactor (30). In the plate-forming step, the mixture (1 1 ) is pressed with the compression screws between the rollers of the compactor (30), and when the material is pressed between the rollers by the screws, the roller movement of the rolls and the pressure and the screws are causing a pressure of about 30-50 bar between the rolls. By means of pressure, a plate (31 ) is formed between the rolls, which first breaks into smaller pieces as it falls in the disintegration step, and by post-treatment it is formed into fertilizer granules (51 ) suitable for forest fertilization with an average grain size of 1 -25 mm, preferably 2-12 mm. The disintegration of the resulting plate into granules is carried out in the disintegration step by means of dropping and/or crushing means (40).

The after-treatment of the granules is carried out in a post-processing device (50) where the grain size is adjusted to suitable, for example, by sieving, whereby the under-sized is returned to the process and over-sized is crushed and returned to the sieve. After- treatment can be done with a plan sifter, filtrate removal by a wind sieve or air knife, drum sieve or roller screen. The plan shifter can be, for example, an eccentric, brake sieve or magnetic vibrator. The sieves may have, for example, a grid, a mesh or a wire sieve as a sieve application.

The fertilizer granule thus prepared hardens due to the pozzolanic properties of the ash and the friction between the particles as the product dries.

Figure 2 shows a method of manufacturing a fertilizer according to the invention according to a preferred embodiment, wherein the nitrogen source, phosphorous source, potassium source, ash, boron source and water are weighed or dispensed by volume. The powdery substances are dispensed from the silos (1 A) or from the large sacks from the dosing funnels (1 B). The moist materials and the filtrate may be fed from the dispensing funnels (1 B) to the mixer (2), whereby the mixture obtained can optionally be pre-compacted at the mass flow rate by rotating sealing rollers (3). The mixture is pressed with compression screws between the rolling rollers of the compactor (4), and when the material is pressed between the rollers by the screws, the roller movement of the rolls and the pressure and the screws are causing a pressure of about 40 bar between the rolls. By means of pressure, a plate is formed between the plates, which is disintegrated into granules by means of dropping and/or crushing means (5). The resulting granules are sieved and the oversize is crushed (6), the undersize can be returned to the process (7) and the finished product (8) is transferred to the warehouse for delivery and packaging.

By combining wood ash and nitrogen source, preferably urea in the same granule, it is possible to avoid separate packaging, transport and, in particular, separate application, since different spreading equipment have traditionally been required for the urea and ash application. In addition, by combining ash and urea with the same granule, fertilizer application rates and the amount of fertilizer to be applied can be reduced as the fertilizer product of the invention is in a more compact and concentrated form. The use of the fertilizer product described herein will also provide easier manageable and cheaper logistics and ensure good application quality. In addition, a major advantage of the invention is that the evaporation of nitrogen is significantly reduced by the fertilizer according to the invention and thus the fertilizer has a better efficiency, i.e. with lower fertilizer amounts, better fertilizer performance is achieved compared to the previous one.

The fertilizer product of the invention is highly nutritious, compact, easy to pack and transport. Fertilizer contains all the nutrients required for wood fertilization, and in particular for the fertilization of soils with medium nutrient content and for more infertile soils of moorlands. The fertilizer is stable and does not break or dissolve when immersed in water.

Preferably, in one embodiment, the fertilizer product is used as a fertilizer, particularly as a fertilizer for peatland forests and/or moorlands.

Thus, the invention provides a novel type of fertilizer product and a method for its manufacture and use of the product, which avoids many of the drawbacks of the prior art and achieves a significant advantage over them. With the use of a fertilizer product according to the invention in forest fertilization it is possible to achieve significant savings especially in the packaging, transportation and application costs of the fertilizer. In the spreading costs, it is possible to achieve significant savings on the time spent on the spreading and on the spreading equipment since the product can be applied with a single spreading occasion and only one spreading equipment suitable for the application of the fertilizer is needed. The invention is illustrated by the following examples, into which the invention is not intended to be limited.

Example 1 describes the composition of a fertilizer product according to an embodiment and the manufacture of a fertilizer product. In addition, the product of the invention has been compared to the ash fertilizer (Table 1 ). Example 2 shows a laboratory test in which the use of fertilizer has been simulated in a fertilizer test pattern describing fertilization in the forest soil.

Example 1

Manufacture of fertilizer product

The fertilizer was prepared by mixing 2.2 kg of sodium borate, 122 kg of urea, 30 kg of superphosphate, 20 kg of potassium chloride, 710 kg of wood ash and 130 kg of water. The mixture was compressed with a compressing roll and then pressed with compression screws between the compact rollers of the compactor. When the screws were squeezed between the rolls, the rotation of the rolls, and the pressure and the screws of the screws caused a pressure of about 40 bar between the rollers. By means of pressure, a plate of 12-15 mm was formed between the rolls, which broke by means of dropping and after- treatment to a granule sized of about 2 to 12 mm. The granule hardened in two days. The finished product contained about 1 1 % of urea and 83 % of ash from the dry matter. The water content of the granule was about 10-12%, the density of 1400-1800 kg/m³ and the bulk density of 1050 kg/m³. The crushing strength of the granules was 3.6 (± 1 .6) kg as determined by the standard method IFDC S-1 15 presented in the following book, David W. Rutland, Manual for determining the physical properties of fertilizer, September 1986 (International Fertilizer Development Center, PO Box 2040, Muscle Shoals, Alabama 35662).

The solubility of the granulate in water was determined by shaking the granules in water for four hours with a plane shaker (water-solids ratio L/S = 2). The dry matter content of the original sample was measured before shaking, and sample and water was weighed into the test vessel. After shaking, the sample was filtered and the water drained into metering glass of 1000 ml. The filter was weighed before filtering. A small amount of solids passed through the filter into the metering glass was allowed to settle and the water was cautiously poured from the surface. Solid matter with filters and precipitate were dried at 150 °C and then weighed. The difference between the dry matter of the original sample and the dry matter of the filtered sample was 18.6%.

Table 1 shows the composition of the fertilizer according to the invention and, in comparison, composition of commercial ash fertilizer (Ecolan T4000) which were analyzed in an accredited research laboratory. The fertilizer granule according to the invention was referred to as nitrogen ash and ash fertilizer as a reference were referred to as ash. Naturally, in the granule of the invention referred to as nitrogen ash granule have a significantly higher nitrogen content due to the urea contained in the granules. Also, the copper and boron concentrations are higher in the nitrogen ash granule than in the ash fertilizer. The product exhibits a concentration variation in those elements the concentration of which is not regulated by the additives, as the ash content of the ash materials varies.

Table 1

Sample: Nitrogen ash Ash

Analyses Result U Result U Unit LOQ Method

Arsenic, As^* 21 + 18 ± 17 mg/kg 3 EPA3051 (HNO3\HCI),SFS

17 % solid

-EN IS01 1885:09

% matter

Cadmium, 3.2 + 4.2 ± 18 mg/kg 0.3 EPA3051 (HNO3\HCI),SFS

Cd^* 18 % solid

-EN IS01 1885:09

o //o matter

Chromium, 84 + 46 ± 15 mg/kg 2 EPA3051 (HNO3\HCI),SFS

Cr^* 15 % solid

-EN IS01 1885:09

% matter

Copper, Cu^* 170 + 83 ± 15 mg/kg 2 EPA3051 (HNO3\HCI),SFS

15 % solid

-EN IS01 1885:09

o //o matter

Mercury, 0.18 + 0.27 ± 17 mg/kg 0.04 EPA3051 (HNO3\HCI),ISO

Hg^* 17 % solid

16772:2004

% matter Nickel, Ni^* 47 + 35 ± 15 mg/kg 1 EPA3051 (HNO3\HCI),SFS 15 % solid

-EN IS01 1885:09

% matter

Lead, Pb^* 41 + 69 ± 18 mg/kg 3 EPA3051 (HNO3\HCI),SFS

18 % solid

-EN IS01 1885:09

o //o matter

Zinc, Zn^* 770 + 990 ± 15 mg/kg 3 EPA3051 (HNO3\HCI),SFS

15 % solid

-EN IS01 1885:09

% matter

Total 42500 + 380 ± 15 mg/kg 100 SFS-EN 13654-1 :en 2002

Nitrogen, N 15 % solid

% matter

Calcium, Ca 16.8 ± 7 14.3 ± 7 % solid 0.05 ASTM C 1301 -95, CEN

_* o //o % matter

ENV 955-4:1997

Potassium, 2.7 + 3.2 ± 12 % solid 0.1 ASTM C 1301 -95, CEN K ^* 12 % matter

ENV 955-4:1997

%

Magnesium, 2.0 + 1 .7 ± 10 % solid 0.02 ASTM C 1301 -95, CEN Mg ^* 10 % matter

ENV 955-4:1997

o //o

Phosphorus, 1 .5 + 1 .2 ± 1 1 % solid 0.01 ASTM C 1301 -95, CEN P ^* 1 1 % matter

ENV 955-4:1997

%

Boric, B 900 + 280 ± 17 mg/kg 4 EPA3051 (HNO3\HCI),

17 % solid

SFS-EN IS01 1885:09

% matter

U = Expanded measurement uncertainty (k = 2), LOQ = Determination Limit

Table 1 of Example 1 shows that the fertilizer according to the invention contains a versatile nutrient composition that is corresponding to the nutrient composition obtained by the separate nitrogen and ash fertilizers. In addition, the heavy metal content of the fertilizer, such as arsenic, mercury, cadmium, chromium, copper, lead, nickel and zinc, is relatively small.

Example 2

Urea degradation into ammonia was investigated by a column test consisting of a woodland-simulating column and the capturing collection section of ammonia. The columns tested the effect of water on the formation of ammonia from urea. The lidded column was 23 cm in diameter and the empty space (2 cm) of the column bottom was separated by the perforated midsole. At the bottom of the column 2cm of empty space was left for collecting of the gravitational water and testing of the gas exchange for the required pressurization of the bottom. On top of the midsole, soil layers were listed bottom-up 5 cm / 2000 g sand (moisture 4.8%), 5 cm / 250 g layer of Vapo dry peat (moisture 32.5%), and gently homogenized homogeneous broth at about 5 cm / 100 g (humidity 85 %). Moss had been harvested from a Myrtillus site type forest in Viitasaari in Central Finland.

To allow the ammonia to be collected through the column cover, a 6-mm diameter pneumatic tube was passed through the floor to empty space, through which air was pumped into the column. The head of the compressed air tube was plugged until pumping through the column was started. The air leaving the column was passed through the lid through a 6 mm diameter compressed air tube into 250 ml freezer flask/bottle filled with water (200 ml) and acidified with phosphoric acid to pH <3. The head of the compressed air tube was plugged and 2mm holes were drilled on the flank of the tube. For the experiments, 16 identical columns were prepared. Columns 1 -2 were blanks (zero samples), columns 3-12 nitrogen amount corresponded to 200 kg/hectare and columns 13-16 nitrogen content corresponded to 500 kg/hectare fertilizer dose. The amounts of water changed to corresponding rainfall varied from 0.2 mm from light dew (80 g) to 3 mm heavy rain (1250 g).

The nitrogen ash grains of the invention used in the experiment were prepared according to example 1 and the urea fertilizer was commercially available (Green Care). Table 2 describes column treatments. Urea (Green Care, nitrogen 46%) and nitrogen ash (6% moisture, nitrogen 4.65%, grain size 2-6 mm) were evenly applied on the moss layer of the columns. The water was finally sprayed onto the columns. Column covers were sealed and compacted and columns were left incubated for 5 days. After 5 days, air was pumped for five minutes through the column at rate of 1 1 l/min to the gas collecting flasks. Columns were opened and nitrogen ash was harvested to determine the total nitrogen content. The ammonium nitrogen content of the gas collecting bottles was determined in accordance with SFS-EN ISO 1 1732: 2005 and the total nitrogen of the grain under the column test in accordance with SFS-EN ISO 1 1905-1 : 1998. Table 3 shows the ammonium nitrogen content of the collection flasks and the total nitrogen content of the grains passed through the column test. Total nitrogen of the nitrogen ash was determined using EPA3051 (HNO3 \ HCI), SFS-EN IS01 1885: 09 methods. The urea content of the total concentration was determined by shaking the sample in water (L / S = 10) and measuring the water urea concentration (Koroleff 1979, The most common chemical analysis methods of sea waters, Finnish Institute of Marine Research, Helsinki).

Table 2

Column no Nitrogen ash Urea (g) Water (g) Incubation

Temperature (°C)

1 0 0 250 20

2 0 0 1250 20

3 20.78 0 250 20

4 20.78 0 500 20

5 20.78 0 750 20

6 20.78 0 1000 20

7 20.78 0 1250 20

8 0 1 .78 250 20

9 0 1 .78 500 20

10 0 1 .78 750 20

11 0 1 .78 1000 20

12 0 1 .78 1250 20 13 0 4.37 0 30

14 0 4.37 80 30

15 51 .9 0 0 30

16 51 .9 0 80 30

Table 3

Column no Ammonium nitrogen Nitrogen content of the grains passed

(mg/l) of water sample through the column test

Total nitrogen %

1 <0.0050 blank (zero sample)

2 <0.0050 blank (zero sample)

3 0.01 0.14

4 0.23 Lacking

5 0.067 0.12

6 <0.0050 0.14

7 <0.0050 0.12

8 0.0057 Lacking

9 0.014 Lacking

10 0.0084 Lacking

1 1 <0.0050 Lacking

12 0.0062 Lacking

13 0.75 Lacking

14 0.17 Lacking

15 0.051 0.27

16 0.066 0.18 Table 3 does not show the total nitrogen concentrations of the granules that passed through the column test in columns 8-14 because the granules were completely soluble in the column test and therefore the determination could not be made.

Results

The impact of ash on nitrogen volatility

There was no clear trend in the ammonia collection fluid between columns 1 -12. No gas was collected from the collection bottles of the driest and moistest columns because the concentration was below the detection limits. During emptying leakages occurred in some of the columns 1 -12 that were likely to affect the result. In columns 13-16 kept at elevated temperature, in the drier treatment, there were 14 times higher ammonia content in the urea treatment compared to the ammonia trap of nitrogen ash grain columns, and in the more humid treatment there were 2.5 times higher ammonia content in the urea treated columns compared to the columns fertilized with nitrogen ash granules.

The granules retained nitrogen. In drier treatments, 13% of the original total nitrogen remained in the granules, and with larger rainfall (about 1 .2 mm and 2.4 mm), 6% of the total nitrogen remained in the granules after five days of starting the experiment.

The nitrogen ash granules according to the invention retain their structure and do not dissolve in rain. Instead, the urea granules will decompose and completely dissolve in the soil even by the influence of the moisture of the moss layer. The solid form of ash fertilizer granules remains in the country for several years.

It should be noted that the above examples of embodiments of the invention are without prejudice to the scope of the invention as set forth in the claims but that the claims are intended to cover all modifications, equivalences and alternatives contained in the spirit and scope of the invention as defined in the appended claims.

Claims

1 . A fertilizer, characterized in that it comprises a mixture of wood ash, nitrogen source and water, the fertilizer is in the form of a granule, the granule has a pH of from 10 to 13.5 and a granule crushing strength of 1 .5 to 6 kg.

2. The fertilizer according to claim 1 , characterized in that the nitrogen source is selected from urea, formaldehyde urea, isobutylidene diurea, methylene urea and mixtures thereof.

Fertilizer according to claim 1 or 2, characterized in that the wood ash is derived from combustion of forest biomass, arable biomass, wood-based sludges formed in the forest industry processes, or the combustion of mixtures referred to above or combustion thereof with peat.

Fertilizer according to claim 3, characterized in that the proportion of forest biomass in the combustion is at least 30 to 100% by weight.

5. Fertilizer according to one of the preceding claims, characterized in that it contains waste ash generated by waste incineration or by waste co-incineration at power plants.

6. Fertilizer according to one of the preceding claims, characterized in that it contains a nitrogen source in an amount of 2 to 32% by weight, preferably 3 to 12% by weight, and 60 to 90% by weight of wood ash, preferably 65 to 85% by weight.

7. Fertilizer according to one of the preceding claims, characterized in that the fertilizer contains an additive selected from boron source, potassium source, phosphorus source or mixtures thereof.

8. A fertilizer according to claim 7, characterized in that boron source is boric acid, sodium borates, ulexite and/or colemanite or a mixture thereof and that the amount of boron source in the fertilizer is 0 to 2.5 % by weight.

9. The fertilizer according to claim 7, characterized in that the phosphorus source is phosphoric acid, apatite, slurry ash and/or superphosphate or a mixture thereof, and that the amount of phosphorus source in the fertilizer is 0 to 6.5 % by weight.

10. A fertilizer according to claim 7, characterized in that the potassium source is potassium chloride, biotite, jarosite and/or potassium sulphate or a mixture thereof, and that the amount of potassium source in the fertilizer is 0 to 30 % by weight.

1 1 . A fertilizer according to any one of claims 1 to 1 1 , characterized in that the solubility of the fertilizer in water is 15 to 20 %, preferably 18 to 19 % by weight of the dry matter.

12. Fertilizer according to one of the preceding claims, characterized in that the average particle size of the fertilizer is 1 to 25 mm, preferably 2 to 12 mm.

13. Fertilizer according to one of the preceding claims, characterized in that the fertilizer has a water content of 7 to 18 %, preferably 10 to 12 %.

14. Use of a fertilizer according to one of the preceding claims as a fertilizer, particularly as a fertilizer for peatland forests and/or moorlands.

15. A method for producing a fertilizer according to any one of claims 1 to 13, characterized in that the method comprises the steps of administering wood ash and nitrogen source into the stirrer, mixing to obtain a mixture comprising water; compacting the mixture; and after-treating the mixture to a granule size between 1 to 25 mm.

16. A method according to claim 15, characterized in that it comprises a pre-compacting step of the mixture for pre-compacting the mixture.

17. A method according to claims 14 or 15, characterized in that the method comprises a plate-forming step wherein in the plate-forming step the mixture is compressed between the rollers of the compactor.

18. A method according to any one of claims 14 to 16, characterized in that in the plate- forming step, the pressing screws and the rolling rolls cause compression pressure to the mixture and the compression pressure is between 30 and 50 bar, preferably 35 to 45 bar.