WO2016132285A1

WO2016132285A1 - A fertilizing composition

Info

Publication number: WO2016132285A1
Application number: PCT/IB2016/050813
Authority: WO
Inventors: Mauro Faneschi; Marco MICCINESI
Original assignee: Microfertil S.R.L.
Priority date: 2015-02-17
Filing date: 2016-02-16
Publication date: 2016-08-25

Abstract

The present invention relates to a novel fertilizing composition with a glass matrix useful as a supplement of trivalent chromium for the plants, mainly consisting of phosphoric anhydride P₂0₅ as a partial replacement of silica, of oxides modifier of this anhydride, i.e. in particular K₂0 and CaO, and of trace elements, and further comprising trivalent chromium that, once assimilated by the plants, represents a valid supplement of trivalent chromium, an essential element in the diet of animals and humans.

Description

A FERTILIZING COMPOSITION

DESCRIPTION

Field of the Invention

The present invention relates in general to the agronomic field, in particular the field of the products for the nutrition of plants, and more precisely it relates to a novel fertilizing composition with a glass matrix useful as a supplement of trivalent chromium, besides being useful as fertilizer and supplement of trace elements for the plants.

State of the Art

It is known for several years the use of glass matrix compositions as fertilizers for plants; they are fertilizers that release in the culture soil for the plants mainly phosphorus and potassium, secondarily calcium, sodium, magnesium, and finally various trace elements, such as copper, iron, zinc, etc. These products have an amorphous structure consisting of a glass matrix wherein trace elements are dispersed and bound, and they can be prepared with processes borrowed from the glassmaking industry technology by fusion of oxides, salts and minerals, bearers of the above mentioned elements to be released, by cooling the melt mass and granulation/milling. Due to their glassy structure and to the insolubility in water, they fall into the category of so-called controlled release fertilizers, as they ensure a slower release of the elements in the soil than conventional fertilizers.

The characteristic insolubility of these products in water makes them particularly appreciated from the environmental point of view, since their use on the ground has no effect other than the release of nutrients for the absorption by the plants roots. In other words, the vitreous matrix fertilizers have not those side effects of the traditional fertilizers that strongly impact on the environment, in particular in terms of pollution of underground aquifers, with consequences on the possibilities of use of water, and on the risk of alteration of the biodiversity.

This environmental impact is caused by the leaching of traditional fertilizers products, generally very soluble in water: the washout of conventional fertilizer products from soil can lead to the impossibility of use of the water for drinking purposes if, for example, the nitrogen concentration exceeds certain limits, while for phosphate compounds the main consequence is the eutrophication of waters, with also considerable damage to the related ecosystems. Even more serious are the consequences that may be caused by the dispersion on the soil of metal chelating fertilizing products, soluble in water, and used just for the release to the soil and plants of metals; the pollution caused by both the chelated products and the free chelating agents, which have already released the metal, can be in fact more difficult to contrast than the other types of pollution referred to above because it can give rise to reactions still little known, and it can generate forms of alteration of the environment for a longer period.

If therefore the fertilizers having a glass matrix represent an excellent alternative to the traditional fertilizers from the point of view of environmental impact, on the other hand they are made so as to release the nutritive elements in the soil and to the plant according to a predetermined pattern that is imposed on the product at the time of production, but that does not necessarily follow the needs of the plant, greatly variable depending on the plant's state of development, the current soil conditions, etc. Moreover many of these products often proved to be quite unable to make available the microelements contained in them, in reasonable times and in effective amount.

The technical difficulty of preparing a vitreous matrix product that has an acceptable ability to release trace elements and is useful for the plant, modulable according to its actual needs, is a technical problem recognized in the art. Indeed, in- depth studies on the plants behaviour have shown that plants are able to modify soil at the level of the rhizosphere, creating all around an environment as much favourable as possible to their growth and, in situations of deficiency of nutrients in the soil, these mechanisms bring to the release from the plant of acidic exudates, that is a mixture of organic acids, such as oxalic acid, citric acid, malic acid and amino acids.

Now, acidic conditions in the soil can make it even more difficult the release of nutrients from a fertilizer having a glass matrix, whose very low solubility can further decrease in an acidic environment. These conditions may also disadvantage the intake of certain nutrients than others, in the sense that the absorbability of a nutrient by the roots of the plants can be strongly influenced by conditions of pH and by the presence in the soil of compounds, such as aminoacids or organic oxyacids. It may therefore happen that, at the very moment in which the plant has greater need for intake of nutrients, their release from the fertilizer decreases and/or decreases their assimilability of the plant, while these factors may increase during periods in which the plant has less need of nutrients.

As far as the Applicant is aware of, furthermore, none of the fertilizers having a glass matrix known up to now has been developed to release, in addition to the main elements and micronutrients mentioned above, also trivalent chromium. This element, in fact, has been so far neglected from the choice of nutrients to be given to plants, possibly also for the extremely restrictive legislation that in recent years have been adopted by the States, and that impose extremely low chromium levels as the maximum threshold allowed.

If on one hand this is understandable and comforting in view of the toxicity of hexavalent chromium and of human and environmental damages it has created in the past, on the other hand it may result in serious damages to humans and wildlife, as it is scientifically demonstrated that chromium, when in the trivalent form, not only is not toxic, but rather represents an essential element to human and animal life, whose deficiency in an organism can cause serious diseases. In this connection it can be mentioned the Opinion of the Scientific Committee on Food (SCF) of the European Commission dated 23 April 2003, which states that the trivalent chromium is an essential element in human nutrition and in animal diet, whose deficiency causes symptoms that can range from weight loss, to alterations in glucose and nitrogen metabolism, to the increase in plasma levels of fatty acids, up to neuropathies.

In animals chromium deficiency has also revealed elevated serum cholesterol and triglyceride levels, with increased incidence of aortic plaques, corneal injury and impaired fertility. These symptoms subside and eventually disappear by taking supplements made from trivalent chromium. Chromium (III) chloride and sulphate are in fact included in the list of substances in the European Directive No. 2002/46/EC, which can be used in the preparation of foods for particular nutritional uses and in the preparation of food supplements.

The trivalent chromium needs for people and animals could therefore be satisfied through a proper diet, which includes for example the consumption of plants that have assimilated this element during growth. But it was reported in the literature that, also in the presence of high levels of chromium in the soil, the amount of chromium in the edible part of the plants was maintained always at extremely low concentrations, of the order of tens of nanograms per Kg of dry weight of the plant. It was moreover observed that the organic matter in the soil can influence the mobility of chromium and, consequently, of its absorption from the plants, because the formation of insoluble complexes of high molecular weight with humic acids causes the immobilization of the metal, which is in this way made unavailable for the plants (see for example S.Canali, F. Tittarelli, P.Sequi, Chromium Enviromental Issues, page 92, Ed. FrancoAngeli).

In view of what stated above, it is now evident how the need is felt to have available a novel fertilizing product for the plants that combine the environmental respect of the products with glass matrix and an efficacious release of trace elements, in particular of trivalent chromium, and to have it efficiently assimilated by the plants, and in particular by their edible portion, by fertilization of their growth soil with the product in question.

Summary of the invention

Now the Applicant has found a novel fertilizing composition having a glass matrix expressly studied for the release of trivalent chromium in the soil in a form that may be assimilated by the plants, included their edible portion, and for the release of other nutrient elements essential for a good growth of the plants.

This novel composition, besides advantages of reduced environmental impact of the products having a glass matrix, has the further advantage of being able to modulate the release of the nutrient elements based on the plant's needs, varying the speed and entity of release of the elements in the glass matrix upon request of the plant, by emission from the root system of organic substances such as citric acid, oxalic acid, and further substances emitted from the plants in situations of deficiency of nutrients, thus favouring also the release of trivalent chromium from the composition and its assimilation of the plant.

Contrary to what is observed in traditional, chromium-containing fertilizers and mentioned above, with the present compositions it was observed a relevant chromium absorption for the plant, that moreover does not influence the absorption also of the other elements and micronutrients present in the composition. It is therefore subject of the invention a fertilizing composition with glass matrix whose essential characteristics are defined in the claim 1 here attached.

The use of the above said composition for the nutrition of plants, a fertilizing product comprising it, and a method for growing plants comprising the administration of the above said composition, whose essential characteristics are defined in the other independent claims here attached, are further subjects of the invention.

Further important characteristics of the present invention are subject of the dependent claims and are described in detail in the following description.

Detailed description of the invention

In the present invention, if not otherwise specified, the amounts of the individual constituents of the composition, expressed as percentages by weight, are to be meant as percentages with respect to the total weight of the composition.

The fertilizing composition with glass matrix according to the present invention has a weight percentage composition, expressed as weight of the individual components with respect to the total weight of the composition, of phosphorus (expressed as P₂0₅) comprised between 26 and 36%, of potassium (expressed as K₂0) comprised between 14 and 24%, of calcium (expressed as CaO) comprised between 5 and 15%, of iron (expressed as Fe₂0₃) comprised between 5 and 16, of manganese and silicon (expressed as respective dioxides) comprised between 2 and 10% for each element, further comprising an amount of trivalent chromium (expressed as Cr₂0₃) comprised between 0.1 and 6% by weight with respect to the total weight of the composition.

According to a preferred embodiment of the present composition, the amount of trivalent chromium (expressed as Cr₂0₃) present in the composition is comprised between 0.2 and 4% by weight with respect to the total weight of the composition; optimal results for release, that represent the best compromise between the amount of chromium added to the composition and the amount released, have been obtained for compositions having an amount of trivalent chromium of approximately 3% w/w expressed as Cr₂0₃.

The present fertilizing composition can furthermore comprise various elements, for example can comprise one or more among the following elements: magnesium (expressed as MgO) in amount ranging from 0 to 10%, copper (expressed as CuO) in amount ranging from 0 to 3%, zinc (expressed as ZnO) in amount ranging from 0 to 10%, aluminum (expressed as Al₂0₃) in amount ranging from 0 to 3%, boron (expressed as B₂0₃) in amount ranging from 0 to 5% by weight, molybdenum (expressed as oxide Mo0₃) in amount ranging from 0 to 2% by weight, and cobalt (expressed as oxide Co₂0₃) in amount ranging from 0 to 2% by weight.

The fertilizing composition of the invention may be used as such, for example in the form of pellets or granules, of powders or of aqueous dispersions, for distribution on the soil for growing plants, or it may be used to prepare a fertilizing product wherein the present composition is combined with other agents and substances agronomically acceptable and commonly used in fertilizing products, for example it can be combined with one or more among dispersing agents, organic composts or soil improvers, and substances for bio-stimulating the growth of plants and/or of their root system.

The present composition may moreover be used also as fertilizer for the plants grown in cultures without soil, commonly used in plant nurseries.

In order to guarantee that the roots of the plants treated are not physically constrained so that it is blocked the emission of organic acids that are signals of nutrients deficiency, the composition of the invention can be for example mixed with organic composts and soil improvers having a spongy substance, wine stillage, and similar, so as to promote development of the root system in proximity of the composition with glass matrix that can be solubilized "upon request" of the plant roots themselves according to their own actual needs of the moment. The possible addition of bio-stimulating substances can then further promote development of the root system, besides development of the whole plant, thus helping even more the response of the glass matrix to the call of the roots in terms of release of trace elements and of trivalent chromium, in a virtuous cycle of continuous and coordinated interaction between the plant and the composition having a glass matrix.

The fertilizing composition with glass matrix according to the invention can be prepared according to a known procedure, by which procedure the glass frits are generally prepared, for instance by mixing suitable precursors of the constituents of the final composition to be prepared, in the form of powder or pellet, by melting at high temperature the so obtained mixture, cooling down the fused mixture and finally grinding the granulate obtained after cooling.

The following examples are given to illustrate the present invention without any limitations to it.

EXAMPLE 1 (COMPARISON)

Preparation of a state of the art composition 1

It was prepared a composition with a glass matrix according to the invention having the composition indicated in the following Table 1.

Table 1

The starting compounds to obtain this composition are indicated in the following Table 2: Table 2

The above said starting compounds were mixed among each other in form of powders and the resulting mixture was fused in an oven in refractory material, bringing the mixture up to a temperature of about 1400°C and maintaining such temperature until a fuse, completely homogeneous mass was obtained, that was sufficiently fluid to be poured in water at room temperature. It was so obtained a "frit" product that was then grinded to obtain the desired granulometry. This product was subject to analysis and it had the composition in the Table 1 above; the product was then subject to the tests described in the following in experiments carried out in parallel with the compositions containing trivalent chromium according to the invention.

EXAMPLE 2

Preparation of the composition 2 of the invention

This composition was prepared by using the same starting elements of the Example 1 , to which it was furthermore added trivalent chromium in the form of chromite in amount of 1 % by weight with respect of the total weight of the composition expressed as Cr₂0₃. The amount of each of the other elements present was proportionally decreased as a consequence of the addition of 1 % of chromium, and the composition was prepared as described above in the Example 1.

EXAMPLE 3

Preparation of the composition 3 of the invention

Similarly to the composition of Example 2, a further composition was prepared but containing 2.99% w/w of trivalent chromium, expressed as Cr₂0₃, always in the form of chromite.

EXAMPLE 4

Preparation of the composition 4 of the invention

Similarly to the composition of Example 2, a further composition was prepared but containing 5.02% w/w of trivalent chromium, expressed as Cr₂0₃, always in the form of chromite.

EXAMPLE 5

Preparation of the composition 5 of the invention

Similarly to the composition of Example 2, a further composition was prepared but containing 3.02% w/w of trivalent chromium, expressed as Cr₂0₃, in the form of chromium oxide.

EXAMPLE 6

Test of release in citric acid

The five compositions with glass matrix prepared as described above in Examples from 1 to 5 were subject in parallel to a test of release in laboratory, with the aim of evaluating the percentage of insoluble residue with respect to the total weight of the composition, as well as with the aim of assessing the amount of trivalent chromium released in a 2% solution of citric acid, that is one of the components of the acidic root exudate and it is contemplated in the Italian Gazzetta Ufficiale as analytical test of release. It was moreover carried out a check of the concentrations of hexavalent chromium in the eluate, that has showed the values far below the maximum values allowed as proof of the non-toxicity of the present compositions. The test was carried out by introducing 1 g of each composition in 1 litre of a 2% aqueous solution of citric acid, maintaining the so formed suspension under moderate stirring at room temperature for 24 hours. At the end of this period of time the suspension was filtered and the filter, previously conditioned, was weighed thus obtaining the weight of insoluble residue. Each solution was instead subject to analysis for determining the concentrations of trivalent chromium and of hexavalent chromium dissolved in each of them.

The concentrations of chromium (III) and of chromium (VI) indicated in the following Table 3 were thus obtained:

Table 3

As it can be seen from the values in the second column of Table 3, the concentration of trivalent chromium in solution, also taking into account the percentage of starting chromium added, reaches optimal values of dissolution in citric acid for values of starting chromium added to the composition around 3% w/w.

As far as the insoluble residue is concerned, in the Table 4 below are reported the values obtained for the five tested compositions: Table 4

EXAMPLE 7

Test of release in organic acids having low molecular weight (LMWOAs; Low Molecular Weight Organic Acids)

The composition having a glass matrix prepared as described above in Example 3 and containing 2.99% w/w of trivalent chromium was subject to a test of release in laboratory, with the aim of quantifying the amount of trivalent chromium and of the other main elements contained in the composition released under conditions that simulate the prevalent conditions in the rhizosphere, reproduced in a laboratory method just known with the name "method of the rhizosphere" or "RHIZO-method", described in Feng M.H. et al. 2005a Chemosphere 59:939-949 and in Feng M.H. et al. 2005b Enviromental Pollution 137:231-240.

In this method the composition under examination is solubilized in a solution of organic acids having low molecular weight (LMWOAs) that simulate, even more realistically than citric acid alone, the acidic exudates of the plants roots. The protocol adopted in this method is as follows: 2.00 g of moist soil of the rhizosphere is mixed with 20 ml of a solution of the following organic acids combined: acetic acid, lactic acid, citric acid, malic acid and formic acid, in 50 ml centrifuge vials previously cleaned. The total concentration of these organic acids was 10 mM, and their molar ratio was respectively 4:2: 1 : 1 : 1. The mixture was stirred for 16 hours, and then centrifuged at 3000 revolutions per 10 minutes. A 5 ml aliquot of supernatant was immediately removed with a pipette and transferred in a 10 ml round-bottom volumetric flask then HNO₃ 2% was added up to the mark.

From the results obtained an even higher release of trivalent chromium was observed in the composition 3 in the solution of organic acids with respect to the release in the solution of citric acid, thus expecting an even better behaviour in soil than in the laboratory, at least for what concerns the release of trivalent chromium. In particular, 3404.33 mg/Kg of trivalent Cr have been detected in the solution of organic acids, and this amount corresponds to over the 10% by weight of the chromium present in the tested frit (2.99%).

It was moreover observed a satisfactory release of all the other elements contained in the composition, comparable to that observed for similar compositions without chromium, this being a sign that the presence of chromium in the composition does not influence its nutritive and fertilizing efficacy on the plant.

* * * * *

The present invention has been described up to here with reference to a preferred embodiment thereof. It should be understood that there can be other embodiments that derive from the same inventive core, all of which are covered by the scope of protection of the claims given hereafter.

Claims

A fertilizing composition with a glass matrix having a weight percentage composition, expressed as weight of the single components with respect to the total weight of the composition, of phosphorus (expressed as P₂0₅) comprised between 26 and 36%, of potassium (expressed as K₂0) comprised between 14 and 24%, of calcium (expressed as CaO) comprised between 5 and 15%, of iron (expressed as Fe₂0₃) comprised between 5 and 16%, of manganese and silicon (expressed as their respective dioxides) comprised between 2 and 10% for each element, further comprising an amount of trivalent chromium (expressed as Cr₂0₃) comprised between 0.1 and 6% by weight with respect of the total weight of the composition.

The composition according to claim 1 , wherein said amount of trivalent chromium (expressed as Cr₂0₃) is comprised between 0.2 and 4% by weight with respect to the total weight of the composition.

The composition according to claim 1 , wherein said amount of trivalent chromium (expressed as Cr₂0₃) is equal to about 3% by weight with respect to the total weight of the composition.

The composition according to any of the preceding claims, further comprising one or more among the following elements: magnesium (expressed as MgO) in amount comprised between 0 and 10%, copper (expressed as CuO) in amount comprised between 0 and 3%, zinc (expressed as ZnO) in amount comprised between 0 and 10%, aluminium (expressed as Al₂0₃) in amount comprised between 0 and 3%, boron (expressed as B₂0₃) in amount comprised between 0 and 5%, molybdenum (expressed as oxide Mo0₃) in amount comprised between 0 and 2% by weight, and cobalt (expressed as oxide Co₂0₃) in amount comprised between 0 and 2% by weight, all the above said percentages being weight percentages with respect to the total weight of the composition.

A fertilizing product comprising the composition as defined in claims 1-4, in combination with one or more among dispersing agents, organic composts or soil improvers, and substances for bio-stimulating the growth of plants and/or of their root system.

6. Use of a fertilizing composition as defined in claims 1-4 or of a fertilizing product as defined in claim 5, for the nutrition of plants and for their enrichment in trivalent chromium.

7. A method of growing plants comprising the administration of a fertilizing composition as defined in claims 1-4 or of a fertilizing product as defined in claim 5, for the nutrition of plants and for their enrichment in trivalent chromium.