SE542424C2 - Fertilizer composition - Google Patents

Abstract

The present invention relates to a fertilizer comprising at least one basic L-amino acid, such as arginine or lysine, wherein a substantial portion of the basic L-amino acid content is present as its monophosphate. The basic L-amino acid phosphate may be combined with a binder and/or provided with an outermost layer acting as a coating. The invention also relates to a method of enhancing the growth of a plant by making a basic L-amino acid phosphate available to the plant.

Description

FERTILIZER COMPOSITION Technical f1eldThe present invention relates to a fertilizer capable of enhancing the growth of plants,a method of enhancing the growth of a plant by making said fertilizer available to a seed or to a plant, and the use of certain amino acid phosphates as fertilizers.

Background Methods of improving soil and/or growth conditions have in principle been appliedsince the first days of agriculture and horticulture. Starting with a very limitedunderstanding of mechanisms, it was recognised that the waste from the householdanimals such as cows improved the growth of crops in the fields. As nitrogen,potassium and phosphorus were identified as the key components required toefficiently fertilize the soil, commercial preparations became widely available and theprinciple of more is less was generally applied for decades, resulting in the by nowwell-known over fertilization effects. While preparations including nitrogen,potassium and phosphorus together with various other mineral nutrients still constitutethe standard in most plant culture, research is continuously improving with regard tothe ref1nement of fertilizer compositions to provide plants with what is needed for theiroptimal growth. Specifically designed compositions for certain plants have beendeveloped, and different formats such as liquids and dry preparations are also providedin order to balance a desired growth, feasibility of application and a minimal environmental impact.

One way to decrease the harmful environmental effects of fertilizers, and especiallythe losses of mineral nutrients to recipient ecosystems, is to develop compositionswhich provide a slow or delayed release of active component(s). Such compositions are often referred to as controlled-release preparations.

Coating of mineral nutrient salts has been proposed as one way of slowing down release. As a common mechanism, coatings have usually acted simply to delay the release of the enclosed nutrients - in the early stages, the coating has prevented anyrelease of nutrient, and once “opened' or consumed, the nutrients all became availableat once. In theory, such released nutrients could either be utilized by the cultured plant,or, if the amount is more than needed, it could leak to the environment. In extreme cases, a large dose of nutrient or fertiliser composition may be toxic to the plant.

Thus, an ongoing challenge in coating technology is to provide for a release Which isextended to a prolonged period of time, at a rate Which is adapted to the needs of the cultured plant.

EP 0509030 relates to solid fertilizei' conipospititaii eonipiisiiig .niicroiiiitrients in theform of inetai sahs together' iafith at least one “itvateißsoltifbie nitrate. A inethod istíeseribed tifhieli includes preitaring the iiiieroiintrient tertiiizer ctfiitiposition in theform of dry aggregate bodies vtfiiieh are aidaptett. to be .mixed ivith a, .niaeitaiiiitiâieiitfïeitiiizer eoiiipositiori, the niethod eoinprisiiig dry iiiixirig ifvitiiout any suhstaiitiai:itíditioii ot" *water satts of :it least 2 iiietais selected fitnii the gieiitp eonsistiiig in" (Én,iviii, Zii. Co and lit/to as itfeii. as at ieast one xvateißsoliibie nitrate ivhicii *is iiot in theform (tia satt of said rnetais. Tiie ratio iietvveeii said iiiierorztitifients and saidniacroiiiitiieiits slioitití be snbstztntiziily above the ratio in vvhich said iiiieitniittrientsand said. iiiaeroiiutrieiits are reqiiired by' erop ialaiits, to obtain att iiitiiiiately iiiixedinieroritittient iiiixttite. 'ilhe resuitiiig iiiicttiiiittrieiit inixttire is coinbirteti *with a binder to iabtaiiii said niicrtiiititrieiit feitiiizer coniptisitioii in the finn: of dry aggiegztte iiodies.

Despite the teachings of the prior art, there is still a need in this area for alternativefertilizer compositions, Which avoid or at least reduce the above-discussed toxicity thatis sometimes associated to the administration of large amounts of nutrients in onegiving. There is also a need for novel fertilizer compositions Which provide forsustained release of nutrient(s), and hence are suitable for less frequent additions to growing plants.

Summarv of the invention The present invention relates to novel fertilizers, which fulf1l one or more of the abovediscussed needs.

Thus, the invention relates to a slow release fertilizer comprising at least one basic L-amino acid, which fertilizer is a solid composition wherein a substantial portion of thebasic L-amino acid content is present as a monophosphate thereof.

Further, the invention relates to a method of enhancing the growth of a plant, whichmethod comprises making a fertilizer according to the invention available to a seed ora plant.

Finally, the invention relates to a monophosphate of a basic L-amino acid for use as afertilizer.

Additional embodiments, details and advantages of the present invention will appearfrom the dependent claims and the detailed description and experimental part that follow below.

Definitions The term “plant” is used herein in a broad sense to denote a species or kind of plant.The term “amino acid” as used herein includes derivatives or modified forms thereof.The term “phosphate” is used herein in its conventional meaning, i.e. for salts or estersof tetrahedral P04 (phosphate) structural units.

The term arginine monophosphate, or ArgP, is sometimes used herein for the monophosphate of arginine.

Brief description of drawings Figure l shows the XRD diffractogram of L-arginine phosphate monohydrate crystalsprepared according to the invention.

Figure 2A-C shows the effect of germination and growth with different types ofarginine-comprising compounds.

Figure 3 shows an illustrative growth-supporting product with a seed and beads comprising an arginine monophosphate fertilizer according to the invention. 3 Figure 4 shows the effect of growth when arginine monophosphate according to theinvention is compared with a commercially available fertilizer composition.Figure 5 shows the effect on growth of Pine seedlings with arginine-HCl and arginine monophosphate, respectively.

Detailed description of the invention A first aspect of the present invention is a slow release fertilizer comprising at leastone basic L-amino acid, which fertilizer is a solid composition wherein a substantialportion of the basic L-amino acid content is present as a monophosphate thereof.

In the present context, the term “a substantial portion” means that the fertilizer iscomprised of a monophosphate of at least one basic L-amino acid as its predominantsource of organic nitrogen. Thus, small amounts of other phosphates may be present,such as polyphosphates remaining from the preparation.

In one embodiment, the fertilizer comprises a monophosphate of at least one basic L- amino acid, and no other phosphate(s).

The basic L-amino acid used according to the invention may be L-arginine; L-lysine;or L-histidine. In one embodiment, the basic L-amino acid is L-arginine and/or L-lysine. In this context, it is to be understood that the amino acids used in the presentinvention may include modified forms of basic L-amino acids, provided that they havemaintained the herein discussed properties for providing nitrogen to seeds or plants.Basic L-amino acids are available from commercial sources. In an advantageousembodiment, the basic L-amino acid is arginine, and the fertilizer is comprised ofarginine monophosphate optionally together with additional nutrient(s) and/or binder(s), as discussed below.

Monophosphates of basic L-amino acids are easily prepared by the skilled personfollowing well known methods. In one embodiment, the present amino acidmonophosphate(s) are crystalline i.e. salts. In an alternative embodiment, covalent coupling is used to prepare the present amino acid monophosphate(s).

One illustrative way of controlled preparation of monophosphates will be providedbelow in the experimental part (see Example l). Alternatively, as the skilled personwill appreciate, salts of basic L-amino acids may be formed by spontaneousprecipitation from a liquid having an undefined content of amino acid(s) and phosphate(s), optionally together with other components.

In one embodiment, the fertilizer according to the invention further comprises at leastone binder. Binders suitable for the preparation of fertilizers are well known in this area, and the skilled person can easily select an appropriate material.

As will appear from the experimental part below, the fertilizer according to theinvention has been shown to substantially avoid the toxicity sometimes associated withlarge quantities of conventional fertilizer compositions. Without wishing to be boundto any specific theory, as the plants to which the fertilizer according to the inventionshow an enhanced growth during prolonged periods of time, the chemical compositionof the fertilizer appears to prevent substantial loss of nitrogen to the environment. Inother words, the fertilizer according to the invention can be regarded as a slow release- type of fertilizer composition.

More specif1cally, the above-mentioned binder may comprise mineral(s) and/or naturalor synthetic polymers.

In one embodiment, the binder is selected from the group consisting of polymers, suchas a synthetic polymer or a natural polymer, e. g. a sugar or a carbohydrate; salts; andminerals.

In a specific embodiment, the binder is a water-soluble polymer, such as polyvinylalcohol (PVA).

In another embodiment, the binder is selected from the group consisting of starchesand sugars.

In yet another embodiment, the binder is selected from the group consisting of calcium-containing salts and calcium-containing minerals.

Having selected a suitable binder, the skilled person can design an appropriatephysical format of the present fertilizer using well known principles of aggregationand coating, or Variations thereof. Some guidance to advantageous formats will be discussed below.

The fertilizer according to the invention may be prepared from a plurality ofaggregates, wherein each one or most of the aggregates comprise particles comprisingbasic L-amino acid(s) which have been aggregated together by mixture with a binder.In this context, the term “mixture wit ” means simply that the particles have beencombined with the binder in a way that holds them together into aggregate(s). As theskilled person will appreciate, in order to prepare particles of amino acids, a nucleus-forming agent may be used. Such agents are well known in the area, and may for example be a non-reactive material such as clay.

Thus, in one embodiment of the present fertilizer, the particles are comprised by one or more nuclei surrounded by the basic L-amino acid(s).

As discussed in the section background above, conventional fertilizer compositions aresometimes coated with an outer layer denoted a “coating”, which protects nutrientsand/or delays the release thereof. The present fertilizer may comprise such a “coating”,the thickness of which may be varied and adjusted depending on the other parameters of the fertilizer.

Thus, in one embodiment, the fertilizer according to the invention is comprised of aplurality of the above-described aggregates enclosed by an outermost layer thecomposition of which differs from the material enclosed by said layer. In thisembodiment, as an example, the outermost layer may be a mixture of a binder with theherein-described amino acid monophosphate(s). By including a certain amount ofamino acid monophosphate in the coating, the fertilizer may provide for early release of nutrient in addition to the delayed release of its inner contents.

In an alternative embodiment, the fertilizer according to the invention comprises anoutermost layer of binder only, and no amino acid monophosphate. Alternatively, af1rst binder may be used to form the aggregates comprising amino acidmonophosphate(s), With or Without the use of a nucleus-forming agent, While a secondbinder being of a different nature from the f1rst binder may be used to form an outermost layer.

As Will be clear to the skilled person in this area, Various embodiments may beprovided based on these principles. For example, basic L-amino acid monophosphatemay be mixed With binder With or Without nucleus-forming agents, and be enclosede.g. by one of the outermost layers discussed above. Further, additional nutrients maybe added to the present fertilizer, either as a component of the particles, as mixed With the binder, and/or as part of the outermost layer.

Furthermore, other additives conventionally used to improve the texture, preservationor other properties of fertilizer compositions may also be incorporated in the present fertilizer.

Further, in addition to the nutrients already provided by the monophosphate of at leastone basic L-amino acid, the fertilizer according to the invention may comprise e.g.potassium, other nitrogen and/or phosphate sources, vitamins, minerals and trace elements, as appropriate.

The fertilizer according to the invention is a solid preparation. In this context, it is tobe understood that the term “solid” is to be understood as opposed to a liquidcomposition. Thus, for example, the humidity of the aggregates Within the outermostlayer may be higher than the outermost layer itself. As the skilled person Willappreciate, the nature of the binder(s) used as Well as the method of preparation Willaffect the degree of solidity of the fertilizer according to the invention. In oneembodiment, the fertilizer according to the invention is solid in the sense that it retains its shape and density When not conf1ned.

A second aspect of the invention is a method of enhancing the growth of a plant,which method comprises making a solid fertilizer, which comprises at least one basicL-amino acid and wherein a substantial portion of the basic L-amino acid content is present as a monophosphate thereof, available to a seed or a plant.

In an advantageous embodiment, the second aspect of the invention uses a fertilizeraccording to the invention, as defined in any of the embodiments above separate or combined with each other.

In one embodiment, the availability of nitrogen and optionally other nutrients to aplant is controlled by arranging a seed in a growth-supporting material, such asmineral, soil or peat, optionally compressed, to which the fertilizer has been added.Thus, the present invention also embraces a product which comprises a growth-supporting material supplemented with a suitable amount of fertilizer according to theinvention, which product is arranged to receive a seed. The growth-supporting materialmay be dried, to allow for subsequent wetting. By wetting the material, a fertilizedenvironment will be provided to each seed supporting and enhancing its growth bymaking available required nutrients, especially N and P, at the rate with which theseedling or plant requires it. Pre-fertilized growth-supporting materials according tothe invention may be prepared in shapes and sizes appropriate for automated or semi- automated plantation.

In one embodiment of the present method, the growth of plant roots is specificallyenhanced. In this context, it is to be understood that even if the growth above ground isalso stimulated according to the invention, the present method provides for a morepronounced increase of plant roots than the prior art fertilizers, as will appear from theexperimental part below. Thus, without wishing to be bound to any specific theory, itmay be speculated that the increase in root growth observed when using the invention in turn favours the plant growth above ground too.

A third aspect of the invention is a monophosphate of a basic L-amino acid for use as afertilizer. In one embodiment, the monophosphate of a basic L-amino acid has been combined with a binder, e.g. in any of the ways discussed above.

In this third aspect, the monophosphate of a basic L-amino acid may be for any of themore specific uses discussed above and elsewhere in the present application, such asfor the enhancement of the growth of a plant during a prolonged period of time using asingle giving or few givings of fertilizer, and/or for avoiding the toxicity sometimes associated with such givings.

Detailed description of the drawings Figure l shows the XRD diffractogram of L-arginine phosphate monohydrate crystals prepared according to the method described in example l.

Figure 2A-C shows the effect of germination and growth with different types ofarginine-comprising compounds. 20 mg nitrogen in the form of Arg-HCL and argininemonophosphate (ArgP) was incorporated into peat and the effect on germination andgrowth was studied.

A) Germination of Scots pine (Pínus sylvestrís) seedlings fertilized with Arg-HCL(left) or arginine monophosphate (right).

B) Dry weight of Scots pine (Pínus sylvestrís) seedlings fertilized with Arg-HCL (left)or Arg monophosphate according to the invention (right).

C) Picture of Pine seedlings fertilized with Arg-HCl (left) or arginine monophosphate(right).

Thus, the solubility of the arginine monophosphate according to the inventionpositively affects growth and germination of pine seedlings. The more rapidlydissolving form of Arg complexes, here illustrated by Arg-HCl, leads to reducedgermination and decreased growth of the seedlings, possibly as a result of nitrogen toxicity.

Figure 3 shows a photograph of an illustrative growth-supporting material according tothe invention provided with seed located in the centre and fertilizer in the form ofbeads comprising arginine monophosphate according to the invention placed in a groove.

Figure 4 shows the result of Pine seeds grown on unfertilized peat with addition of 10mg N from different arginine compositions mixed in the peat before germination. Pineseedlings were harvested at the end of the growing period (three months) and dry weight was measured. The figure shows a clear difference in growth depending on the form of the arginine.

Figure 5 shows the effect on growth with arginine-HC1 and arginine monophosphate.Four single doses of different amounts of nitrogen (20, 40, 80 and 160 mg N,respectively) were added to Pine seedlings grown on unfertilized peat in thegreenhouse for 10 weeks. Arginine monophosphate according to the invention isshown by the uppermost curve (I), and Arginine HC1 (O) below. As appears from thisfigure, with an equivalent coating, there is a substantial difference in growth between Arg HC1 and the arginine monophosphate according to the invention.

EXPERIMENTAL PART The present examples are provided for illustrative purposes and should not beconstrued as limiting the invention as defined by the appended claims. All referencesprovided below and elsewhere in the present application are hereby included herein Via reference.

Example 1 - Preparation of arginine phosphate monohydrate crystals The objective of this example was to prepare phosphate crystals of amino acids to beused as fertilizer for plants in accordance with the invention. Though arginine isdescribed below, the skilled person can easily use the method for the preparation oflysine as well.

L-arginine was obtained from a commercial source. 85 % orthophosphoric acid wasobtained from Merck (Darmstadt, Germany). Millipore water of 18 MQ resistivity wasused to prepare the solutions.

A supersaturated solution of arginine phosphate (monohydrate) was prepared bydissolving L-arginine in purif1ed water at 60°C. An equimolar amount oforthophosphoric acid was added whereby the solution temperature increased to about80°C. The arginine phosphate solution was slowly cooled at a rate of approximately5°C/hour. Nucleation of arginine phosphate occurred spontaneously at a solutiontemperature of about 60°C. Crystal growth continued as the temperature decreasedfurther. After reaching a temperature of 5 °C, the remaining mother liquor was pouredoff. The crude crystals were dried by vacuum f1ltration followed by drying in a heatcabinet at 35°C for approximately 24 hours. The crude crystal yield for the first threetest batches was between and 82 and 90%.

To remove soluble arginine and phosphate adsorbed on the crystal surfaces, thecrystals may be washed with a small amount of cold water during the vacuum filtrationstep. Preliminary tests indicate that the yield of washed crystals is between 75-80 %.The crystal structure of the formed crystals was confirmed by XRD analysis. The diffractogram is shown in figure 1. 11 Example 2 - Growth and germination of Pine (Pinus syiïßestrvzÉs) seedlings Withdifferent fertilizers Pine seedlings Were grown in unfertilized peat (80 ml per plant/pot) with 20 mg N ofone of the following arginine fertilizer compositions: Arg-HCl or arginine monophosphate. The plants were grown in the greenhouse l6h/8h (day/night) at 23C° andgermination Was measured after 3 Weeks. Plants Were harvested and rinsed to removeall soil from the roots and then dried in 65 C° for 24h. Dry weight was measured after5 weeks. The results are presented in Figures 2A-C Example 3 - Field test on Pine (Pínus .sylifesïrís) With coated Arg-HC] and argininemonophosphate according to the invention 30 mg N per plant in the form of coated Arg-HCl or ArgP were mixed in peat andloaded to cassettes. Pine seeds were added and the plants were grown in greenhousesfor 5 weeks with only water addition once per day and then moved outside and grownfor 5 weeks more. Plants were rinsed to remove all soil from the roots and dried in 65 C° for 24 h. Dry weight was measured. The results are shown in Figure 4.

Example 4 - Field test With beads comprising different forms of nitrogen Solid arginine monophosphate was prepared. The crystals formed were grinded intosmaller particles, which were mixed with binder and formed into beads comprisingarginine monophosphate according to standard coating procedures.

Two additional nitrogen containing beads were included in the field test.Commercially available Arginine-HCl was treated as above to create argHClcomprising beads.

The commercial available nitrogen comprising bead to test was a coated NPK fertilizerthat releases nitrogen, phosphate and potassium and trace elements over a pre-chosenperiod of time.

The amount of nitrogen was calculated for each of the three different types of beads.Beads with approximately 10 or 20 mg was placed in the vicinity of pine seeds place in the sowing unit presented in WO20l5030656 as illustrated in figure 3. 12 One hundred (100) sowing units was used with the two levels of nitrogen and planted outdoors.

Rllß The first comparison was made between the beads with the two arginine comprisingcompounds. Seeds of Scots pine (Pínus sylvestrís) were seeded and fertilized and thegerminated seedlings was counted. The germination rate was calculated and summarized in Table l and Figure 2 and 4.

Arginine argHCl beads monophosphate beads l0 mg l0 mgGermination rate (%) 78% 67% 20 mg 20 mg argP argHClGermination rate (%) 78% 68% Table l. Germination rate with argP and argHCl beads Based on these results it was obvious that germination and plant formation was muchbetter when both nitrogen and phosphorous was present in the beads.

The second comparison was made between the argP beads and the commerciallyavailable beads both embedded in the sowing unit as seen in figure 3. The sowing unitswere tested at a plant nursery. 19 weeks after planting, the sowing units with thearginine monophosphate beads or the commercially available coated beads, plantletswas harvested and the total dry weight was measured as well as the shoot and the root.Surprisingly, it was then noted that the total dry weight of the plantlets wassignif1cantly larger, i.e. the plant grown from the sowing unit comprising the argininemonophosphate fertilizer according to the invention was approximately 20% largerthan plants grown from the sowing unit with the commercial nitrogen fertilizer used.This was even more pronounced when the dry weight of the root was measured, 50%, which is summarized in the table Y and Figure 4 Commercialcoated argP 13 nitrogen fertilizer 10 mg N 10 mg NDry Weight shoot (g) 0,081 0,074 9%Dry Weight root (g) 0,042 0,028 50%Total Weight (g) 0,123 0,102 21% Table 2. Comparison between argP beads and commercially available coated nitrogen fertilizer.

Example 4 - Toxicity test on Pine (Pinus svívestris) seedlings With different coatedarginine fertilizers Pine seedlings groWn in unfertilized peat (80 ml per plant/pot) With single doses ofdifferent amounts of added nitrogen (20, 40, 80 or 160 mg N) With two differentcoated arginine fertilizers - Arg-HCl and arginine monophosphate according to theinvention). Plants Were groWn in the greenhouse 16h/8h (day/night) 23C° Plants WereharVested after 10 Weeks, rinsed to remove all soil from the roots and dried in 65 C° for 24 h. Dry Weight Was measured. The results are shown in Figure 4. 14

Claims (13)

1. l. A slow release fertilizer comprising at least one basic L-amino acid, which fertilizer is a solid composition comprised of a monophosphate of at least one basic L-amino acid as its predominant source of organic nitrogen.

2. A fertilizer according to claim l, which further comprises at least onebinder.

3. A fertilizer according to claim 2, wherein the binder comprises mineral(s) and/or natural or synthetic polymers.

4. A fertilizer according to »Tà»~~~2, wherein the binder isselected from the group consisting of polymers, such as a synthetic polymer or anatural polymer, e.g. a sugar or a carbohydrate; salts; and minerals.

5. A fertilizer composition according to claim 4, wherein the binder is awater-soluble polymer, such as polyvinyl alcohol.

6. A fertilizer composition according to claim 4, wherein the binder isselected from the group consisting of starches and sugars.

7. A fertilizer composition according to claim 4, wherein the binder isselected from the group consisting of calcium-containing salts and calcium-containingminerals.

8. A fertilizer according to any one of the preceding claims, which iscomprised of a plurality of aggregates each comprised of particles comprising basic L-amino acid(s) aggregated together by mixture with a binder.

9. A fertilizer according to claim 8, wherein the particles are comprised bynuclei surrounded by the basic L-amino acid(s).

10. A fertilizer according to claim 8 or 9, wherein each aggregate presents anoutermost layer the composition of which differs from the composition enclosed bysaid layer.

11. ll. A method of enhancing the growth of a plant, which method comprises making a solid slow release fertilizer, which is comprised of a monophosphate of at least one basic L-amino acid as its predominant source of organic nitrogen, availableto a seed or a plant.

12. l2. A method according to claim ll, Wherein the availability of nitrogen andoptionally other nutrients to said plant is controlled by arranging the seed in a growth-supporting material, such as mineral, compressed soil or compressed peat, to Which thefertilizer is added.

13. A method according to claim l l or l2, Wherein the growth of plant roots is enhanced.