MXPA98000971A - Format of fumigate of iron or of other meso and nutritive microelements available for lanutrition of the plants and method for obtene - Google Patents

Abstract

A compound is described between the humic substances and the iron called "iron fumigation" characterized by having a structure of the type: where the metal is protected against the pyrophosphate and against the humic substances (SU), obtained through a process comprising the following steps: a) dosing of the humic extracts, b) purification of said humic extracts through centrifugation or filtering by pressure to remove any suspended particles that may exist, c) transfer of the floating product to a mixer d) addition of K4P2O710H2O by completely dissolving it, e) mixing of solution d) with an aqueous solution of FeSO47H2O with a minimum amount of H2SO4 operating the aggregate slowly and having vigorous agitation the humic extract; f) after agitation of a few minutes, quick drying at 60-90

Description

STABLE FORM OF FUMIGATED IRON OR OTHER MESO AND NUTRITIONAL MICROELEMENTS AVAILABLE FOR THE NUTRITION OF THE PLANTS AND METHOD TO OBTAIN IT TECHNICAL FIELD OF THE INVENTION It is known that the meso and microelements essential for the nutrition of plants are mainly calcium, magnesium, sulfur, iron, manganese, copper, zinc, boron and molybdenum. In agrarian conditions, situations of nutritional deficiency can be verified, mainly due to an insufficient availability of iron, calcium and magnesium and sometimes also of the other elements. In fact, the soil often contains abundant amounts of these elements, but most of them may be present in insoluble forms, such as, for example, oxides (for example Fß2? 3), hydroxides (for example, Fe (0H)). 3) and carbonates (for example, CaC? 3 and MgC03), not available for vegetable nutrition since they are in the insoluble crystalline or amorphous form. There are few plant species that, in case of need dictated by the absence of more available forms, are in a position to set in motion an effective, but costly biochemical process that allows to carry to the soluble form elements precipitated in the form of oxides, hydroxides or carbonates. The mechanisms illustrated in the examples, apart from iron, calcium and magnesium, may be valid for manganese, copper and zinc. All these nutrients, therefore, must be present in the soil under the form available for assimilation, to be used by the plants. In the soil there are different physical phases: a gaseous, a liquid and a solid phase; The latter is composed of a mineral part and organic materials. The organic materials, in turn, comprise humic substances and non-humified substances, and derive from the contribution and transformation of animal and vegetable organic waste. The humic substances are of complex polymeric nature and possess numerous functional groups, predominantly carboxylic and phenolic; they are very stable over time, difficult to attack by microorganisms and able to develop a series of agronomic functions maintaining a certain level of soil fertility. The nutritional functions of humic substances are: 1) direct type, when there is a release of the nutrients during the slow mineralization of the same humic substances; 2) of indirect type, when, for example, its ability to compose and chelate the metals that are in the liquid phase is used, to then transfer them to the plants.

In nature, said indirect-type nutritional function is considered the most important to make available different metallic nutrients, such as iron, calcium and magnesium. The humic substances, in fact, tend to chelate the metals present in the soil solution, thus preventing precipitation in the form of oxides, hydroxides or carbonates, unusable since they have insoluble forms, inaccessible to the roots of plants. This chelation, in turn, makes metals available for nutritional processes. Fertilization can be done substantially in two ways: by foliar or through the soil. In foliar fertilization the fertilizer is absorbed through the tissues that line the outer part of the leaves, therefore it can happen only with fertilizers that have a molecular structure of very small dimensions and this vehicle is used predominantly to solve problems of lack momentary nutritious. Different is the case of fertilization through soil, which is the means that ensures in nature the nutrition of plants.

BACKGROUND OF THE INVENTION The sector of the present invention covers the fertilization that occurs through the soil, the latter being understood as a natural means to make the fertilizer available to the root system of the plants. It is about, therefore, to prevent the fertilizer, consisting of a common salt, for example ferrous sulfate (FeS? 4), introduced in a soil lacking iron, with a neutral-alkaline pH (eg, pH 7-8). ) and poor of humic substances, is transformed into insoluble products such as oxide, hydroxide and carbonate. From an ideal point of view, a fertilizer based on meso and icroelements to be used for soil fertilization should have the following characteristics: 1) have the metal attached in an assimilable way, ie transformable, where it is not originally, in a soluble form and, therefore, available for radical system nutrition; 2) have a sufficient bond strength so as not to lose the metal in the soil, but not too high to allow the agents quelates of the roots to separate it and make it available for the biochemical processes designated for the absorption by the vegetables; 3) not be easily degradable in the soil to be able to keep the metal in a chelated form for quite a long time, corresponding at least to the whole crop cycle. There are currently three main categories of fertilizer based on meso and microelements: a) Inorganic salts, which do not have the capacity to make the fertilizer available for the roots for a sufficiently long period; b) Organic compounds, which are substantially organic salts with functional groups (eg, citric acid) capable of binding a metal, including strongly. Said compounds often do not allow a good use of the metal both because of the biodegradability due to the attack of the microorganisms and because of the binding force too intense, which does not allow the release of the metal and its introduction in the biological cycles; c) Organic chelates that are characterized by the composition of the metal with several coordination junctions by polyvalent molecules that envelop it by protecting it with a configuration that can be represented as a pincer, or a chela. The structure of these compounds, therefore, is such as to offer sufficient repair to the metal, keeping it available for a sufficiently long time. This means that in theory, a fertilizer contribution through an organic chelate manages to satisfy the demands of a crop for quite a long time. These types of chelates, however, do not prevent the activity of the microbes and suffer, therefore, a fairly rapid degrade, such that the availability of the metal in the soil is not allowed throughout the temperate of the crop. Therefore, it is possible that in this case the cultivated plants live for a period of the year in a stage of nutritional deficiency, especially if they are poly-annual species (eg fruit plants). It is known to use as organic salts some derivatives of the tartronic acids and their salts in the variants with and without the mobilization of the phosphates, as can be seen in the Italian patents n. 767605, n. 788509 and n. 833128. Other organic chelates and salts are described in US patents 4,181,516 (Gray, 1980) and 4,786,387 (Marihart, 1988) and in European patents 284339 Bl (Marihart, 1991). In these last two patents, fulvic acid (a fraction of the humic substances) is used together with various chelators and anhydrous ammonia (with the aim of neutralizing the mixture) without obtaining the formation of bridge protection structures of the type that is the object of the invention. present invention. In a work published by D. F. Cle ens et al. in Fertilizer Research Vol 25, p. 127-131 (1990), the structure of chelating agents and related metal compounds is described, such as those of Fe (III), distinguishing it into two classes: the aminopolycarboxylates and the hydroxycarboxylates (where the term carboxylated means "functional group of a organic acid "). For example, the class of the aminopolycarboxylates belong to EDTA (etylamylaminotetraacetic acid), and also EDDHA (ethylenediamine (o-hydroxyphenylacetic acid)) h * to the class of hydroxycarboxylic acids belong, for example, citric acid, gluconic acid, glucoeptonic acid. The structure of the humic substances corresponds to the characteristics required by an ideal chelant-coplayer. For the purposes of plant nutrition, the humic substances are, in any case, the ideal complexing agents for iron and for the other nutritive elements, as is known from the technical literature, for example according to FJ Stevenson "Humus Chemistry" J Wiley &; Sons Ed. (1982), and according to F. Sequi "Organic groundlessness, Funzioni nutrizionali" (The organic substance in the soil, Nutritional functions ", Agricultural Italy 113 (2): 91-112 (1976). of the humic substances is not well defined in the part that affects the chelation of metals, however, it is known that the humic molecule preponderantly uses the -OH of the functional groups to be able to complex the metallic elements (Stevenson, 1982). According to some authors, the structure of the metal-fumigated complex affects two hydroxyls, one of which is carboxylic and one that derives from another functional, alcoholic, phenolic or other group, as indicated by Sequi (1976), the structure of the compound often also includes a phosphate group that in the matter has two functions: 1) to protect the metal (for example, iron) from being "wrapped" completely by the humic substances and, therefore, to be less available for the plants, and 2) be, in turn, available as such for plant nutrition. For this purpose it should be remembered that phosphate also has significant availability problems in the soil as it easily goes to precipitation processes. According to Sevenson (1982), the extraction of humic substances using a base such as NaOH or KOH is produced by salification of the humic and fulvic acids in an alkaline environment according to the following reaction: HA-OH + K-OH - > HA-OH + H2O where HA-OH is humic acid. The K + can also be replaced by Na +; the compound that is formed (HA-OK or HA-ONa) is a salt of humic acid (fumigated). In the case that a non-alkaline metal (eg iron) is bound to the humic molecule, only the base (KOH) is not able to salify the humic acid and the extraction of the humic acid compound with the metal must be produced with the help of a salt that has a chelating agent, such as sodium or potassium pyrophosphate. As indicated by Stevenson (1982) the reaction that would lead to the humic acid solution could be as follows: HA-O-Me + I / 4K4P2O4 - > HA-OK + l / 4Me¿P207 In other words the metal would be separated from the humic acid and replaced with the K +, thus giving rise to a salt of humic acid, while the metal would form a compound with the pyrophosphate giving rise to an insoluble salt that would precipitate ().

Said reaction is likely to occur only if the iron complexer has a binding strength lower than that of the pyrophosphate, but can not happen at the moment when the organic complexer (humic substance in the specific case) has a binding strength greater than that of the inorganic complex (pyrophosphate). In a process of extraction of the humic substances, that is to say of solubilization, the combined action of the two extractors KOH and K4P2O? allows the realization of the following phases (Stevenson, 1982, E. Bar-Ness and Y. Chen Plant Soil, 130, 35-43, 1991): 1) solubilization by the work of KOH, in the form of potassium salts, of the humic substances not composed of metals; 2) solubilization by the work of K P2O7, in the form of potassium salts, of the humic substances bound to metals with low chelating force with simultaneous precipitation of the metal-pi-phosphate compounds; 3) solubilization by the work of K4P2O7 of the humic substances joined to metals with high chelating force with the formation of a compound between the humic substance and the pyrophosphate by a metal bridge. This phase is confirmed by Stevenson (1982) when it describes the criteria for extraction (solubilization) of copper from the soil: the form bound to the organic substance, in fact, is extracted with pyrophosphate. The same reaction is described in the work of Bar-Ness and Chen (1991), when there is talk of a notable presence of iron in the organic substance extracted from a peat previously composed of iron. On the occasions mentioned and in other cases in which it has been sought to prepare metal chelates based on humic substances for research or commercial supply purposes, to provide a product with superior quality and performance to those of the products present on the market , the following problems have been verified: - in many cases, mainly due to erroneous stoichiometric calculations, the addition of the metal to the humic extract (saline aqueous solution with humic substances in solubilized form) led to an immediate flocculation of the extract; the chelates based on humic substances prepared up to the present were presented in the liquid state, in the form of a solution, but the solubility of the product was very low because of the polymerization phenomena that took place in a few days: only the compounds of the metals with fulvic acids (US Patents 4,186,387 and European Patent 284,339) could be soluble by the presence of other chelating substances, as has been said above; the amount of metal bound to the humic substances was always very low and not enough to justify the introduction of a commercial formulation on the market (Lobartini and Orioli, Plant Soli, 106, 153, 1988); the products were not soluble after drying; this showed the fact that the presence of the metal had favored the formation of a closed polymer and, therefore, of a flocculation.

DESCRIPTION OF THE INVENTION The aforementioned problems and others presented by the techniques and by the known products are solved by the invention which describes a stable composition of fumigation of iron or other meso and nutritive microelements available for plant nutrition and the method for obtaining it. In the case of the present invention, the humic substances that are used as raw materials are already in extractable form (for example, humic extracts obtained through the extraction with KOH of the humic substances of leonardite) and, therefore, we are in front of potassium salts of organic acids. Obviously, it is a very complex mixture in which there are both low and high chelating compounds. The productive process object of the present invention foresees the following passages: a) To the humic extract obtained by solubilization of humic substances with an aqueous solution of KOH or of another alkaline reagent, after a careful elimination through centrifugation or filtering by pressure of the parts that could be in suspension, a quantity is added, to be defined according to the characteristics of the humic extract, of a molecule of the pyrophosphate type (K P2O7) . In this phase, nothing is done other than mixing the components without causing any specific reaction. b) To the solution obtained in step a), slowly in order to make possible the chelation / complexification reaction, but immediately, a solution of FeS? 4 or another inorganic salt completely soluble in water is added. If the salt is said ferrous sulfate, now the iron, the humic substance and the K4P2O7 react with each other according to the mechanism described below: the humic substances contained in the extract may have a complexing force very different from each other, but at purposes of the mechanism of reaction with Fe (II) and K4P2O7 we are interested in subdividing them into two categories: 1) humic substances with chelating strength superior to that of K4P2O7 and; 2) humic substances with lower chelating strength than that of K4P2O7. When an ion of Fe (II) is added to the solution containing the humic substances in potassium form and K4P2O7, the metal is bound by coordinated bonds to the humic molecule with the highest chelating force and simultaneously forms a bridge with a phosphate of K4P2O7 forming a phospho-metal-fumigated compound. The evidence of this reaction is given by the fact that, if the metal were bound only to K4P2O7, a light-colored precipitate would form, while a reaction would only occur between the humic substance and the iron, forming a precipitate dark. Said reaction is verified until all the humic substances with chelating force superior to those of K4P2O7 have not reacted with iron and, therefore, with K4P2O7. To such an extent, if we continue to add Fe (II) it has been observed that the metal forms a compound through K4P2O7 because it is now the free complexer with the highest binding strength. As proof of this, the immediate formation of a whitish flocculate can be observed. In the process object of the present invention, it is not necessary to use salts of organic compounds, since one would not be sure of said reactions of formation of chelates / compounds by the humic substances, but there would be the risk of obtaining a mixture of humic substances and the metallic compound, which presents the problems described above. With the method of the present invention a soluble compound is formed between the humic substances, the metal and the pyrophosphate, quite stable so as to be able to be dehydrated (dehydration must occur immediately after the preparation phase). The dehydrated product can be completely redissolved in water and, therefore, can be used to fertilize the soil through the practice of irrigation fertilization. The final product has a total iron content, completely related to humic substances, equal to or greater than 3-4% depending on the organic matrix used for the extraction of humic substances. By using optimal humic extracts, an iron fumigation is achieved, which contains approximately 4.5% iron chelate. This title (concentration of dissolved substance) may be lower if organic extracts of peat, compounds or other less fumigated organic matrixes of leonardite are used. With some humic extracts of coal dust a title equal to 7% of bound iron has also been obtained. If metals with an atomic weight and valence different from those of iron are used, it is obvious that the metal titles composed of the humic substances will be different. The main reason why in most cases refers to iron is that this nutritive element is undoubtedly the most critical in the nutritional deficiencies of meso and microelements. The quantities of the reagents must be calibrated perfectly in order to prevent the addition of an excess of metal and, therefore, cause a precipitation of Fe-pyrophosphate and / or humic substances polymerized around the iron. The iron fumigates prepared so far were characterized, at a neutral to alkaline pH value, by a structure similar to the following: In this situation the metal ion, notwithstanding the alkalinity of the medium, causes the rapid polymerization of the humic substance forming a compound of the type: SU-0 i ^ 0-SU ^ '^ "" "Fe-r' su-o ^ i" ^ -o-su The polymerization could be prevented only by drastically reducing the content of bivalent metal (Fe) so as to entrust potassium, as counter-ion, with the task of having the compound in solution. In other words, the potassium ion must neutralize most of the charges of the functional groups of the humic substances, preventing the polymerization by iron. Based on what has been said previously and on the available information, it is considered that iron fumigation, from the chemical point of view, is formed in this way, With such a structure the metal is protected against pyrophosphate and against humic substances and also prevents rapid flocculation of the compound due to the creation of possible coordination junctions. To carry out the products object of the present invention, the following procedures are indicated, by way of example but not limited to: EXAMPLE 1 The following phases have been provided: a) the humic extracts have been dosed in a way corresponding to 3 kg of dehydrated humic extracts; b) said humic extracts have been purified from the suspended particles (clay substances and organic colloidal material in suspension), by centrifugation; c) the fleet product has been transferred to a mixer; d) an amount of 1.5 kg of K4P2O7IOH2O has been added to the mixer and completely dissolved; e) an aqueous solution of 1 kg of water is prepared separately FeS? 7H? in 10-15 liters of water, with the addition of a minimum amount of H2SO4 to avoid oxidation of Fe (II) to Faith (III); f) solution (e) has been added slowly to solution d), stirring the humic extract simultaneously and rapidly; g) the agitation has been carried out for 5 minutes and then it has been quickly provided for drying. In total, 4.5 kg have been obtained. of finished product with an iron bound title equal to -6. The obtained product has been subjected to poor iron soil, in a controlled environment, for agronomic tests in comparison with other classic chelates (EDDHA-Fe) and the following results have been obtained: all the experienced horticultural plants (cucumbers, strawberries, etc.) have yielded significantly better results from the quantitative and qualitative point of view if they had been fertilized with iron fumigation, while the other classic chelates provided positive results only temporary and discontinuous. From the results mentioned above, the greater fertilization efficiency of the product object of the present invention is demonstrated, in comparison with the products that are currently used for the nutrition of plants. There are numerous variants to Example 1 mentioned above since the humic extracts can have different origins and, therefore, can be obtained with a variety of solvents, at different pressures and temperatures, and come from all organic matrices containing humic substances or similar (eg peat, lignite, leonardite, carbon, organic fertilizer, compound, sludge, sewage, land, etc.). In addition to the iron salts, the process can also be applied to the salts of other metals essential for the nutrition of plants, such as calcium, magnesium, zinc, etc. Apart from the rapotassium tet pyrophosphate dehydrate, other types of calcium can be used. pyrophosphates and metaphosphates, pyrophosphoric and metaphosphoric acid and all organic and inorganic compounds containing phosphorus, with the condition to regulate the reaction with buffer systems.

EXAMPLE II A fruit orchard consisting of twenty rows of pear plants (pears) suffering from iron and zinc deficiency has been fertilized, by groups of four rows, in the first row with a product identical to that described in Example I, in the second row with a totally analogous product, except for its preparation conducted with zinc sulfate instead of iron, in the third row with a mixture of the previous two, while the fourth row of the fertilizer was not carried out. As confirmation, each subsequent group of four rows was paid in the same way. Production clearly improved in the first and second rows of each group, but only in the third row did it become abundant and qualitatively perfect. The plaste of the fourth row deteriorated and its production was of very low quality. In the five years following that of the abandoned, the plants of the third row continued to manifest themselves in full vegetative and productive vigor, while those of the first and second were reducing their production and those of the fourth until the death was had of some plants, with consequent faults along the row.

EXAMPLE III Some rows of an orange fruit orchard implanted on a strongly calcareous land lacking iron were fertilized, plant by medium, with a product identical to that of Example I, except for its preparation, which had been conducted with sodium metaphosphate instead. of potassium pyrophosphate. The tests gave excellent results in terms of quality and quantity only in the abandoned plants. The positive results were confirmed for four years after the subscriber. The invention conceived in this way is susceptible to numerous modifications and variants, all within the scope of the same concept of the invention. In practice, obviously, modifications and / or improvements can be made that, in any case, are always within the scope of the following claims

Claims (5)

NOVELTY OF THE INVENTION CLAIMS

1. - Humic compound called "fumigated iron" that has a structure of the type: where the metal is protected against pyrophosphate and against humic substances (SU), obtained through a process characterized by the fact that it comprises the following phases: a) dosage of the humic extracts; b) purification of said humic extracts through a centrifugation or filtering by pressure to eliminate the particles in suspension that may exist; c) transfer of the floating product to a mixer; d) preparation of a solution K4P2O7IOH2 e) mixing solution d) with an aqueous solution of FeS? 47H2? which contains a minimum amount of H2SO4 operating slowly and having vigorous agitation the humic extract; f) after stirring for a few minutes, dry quickly.

2. - Product obtained with the method of claim 1, characterized in that it has a structure of the type:

3. - Product obtained according to the process of claim 1, characterized by containing metals, instead of iron, calcium, magnesium, manganese, copper, zinc, cobalt, and any element useful for nutrition vegetable, in its different oxidation states.

4. Product obtained according to the methods described in the preceding claims, characterized in that they have employed, in the course of preparation, molecules other than pyrophosphate, but able to form bridges with iron to the other metals that, in turn, they are united in the humic substances.

5. Product obtained according to one of the methods described in the preceding claims, characterized in that it contains artificial humic substances, or fractions of natural or artificial humic substances, soluble and insoluble.