DK150637B - Plant food solution and process for its preparation - Google Patents

Description

150637

The present invention relates to a plant nutrient solution with macronutrients consisting of Mg and P and intended for use in the preparation of a liquid, with respect to its content of plant nutrients such as N, P, K, S, Ca, Mg, 5 Fe, Mn, Zn, Cu, B, Mo, and Co complete nutrient stock solution for nutrient enrichment of irrigation water. The invention also relates to a process for preparing said plant nutrient solution.

Within certain types of plant cultivation, it is advantageous and useful to add the necessary plant nutrition for irrigation, often with each irrigation, dissolved in the raw water used for irrigation. Generally, 2 150 S37 is prepared, whereby one or more commercially available water-soluble, solid and / or liquid plant nutrients and water is relatively concentrated, with respect to its plant nutrient complete stock solution. This stock solution, containing mainly in the form of dissolved salts, contains both macronutrients, e.g. N, K, P, S, Ca and Mg, as well as micronutrients, e.g. Fe, Mn, Zn, Cu, B, Mo and Co. is then dosed in the raw water to form nutrient-enriched irrigation water with a total content of dissolved nutrients of, for example, one or a few ten to ten parts by weight, although higher concentrations may occur. By preparing the stock solution at the place of cultivation from several different plant nutrients, the grower can adjust the composition of the stock solution according to the current nutritional needs of the cultivated plants in the cultivation environment 15 and taking into account any nutrients already present in the raw water available for irrigation.

To rationalize the preparation of such stock solutions, pre-composed micronutrients are available in the form of a dry product or in the form of an aqueous solution having a dry matter content of approx. 25% by weight in which mixtures of the micronutrients are present in combination with chelating organic compounds. In addition, there are in the trade an approx. 50% plant nutrient solution containing Mg and P in an amount proportional to the consumption of these nutrients. However, necessary temperature stability (no crystallization of salts at normal operating temperatures) could only be achieved by the addition of nitric acid or another strong acid, which complicates the preparation of the stock solution by making the Mg 30 and P containing solution caustic and additionally requiring great caution in the addition. of the chelated micronutrient which, in contact with the strong oxidizing acid of the Mg and P-containing solution, could be decomposed during precipitation of highly soluble micronutrient salts in the stock solution without value to the plants. One way to avoid these drawbacks would be to use a Mg and P containing solution with a sufficient concentration of phosphoric acid sufficient to obtain acceptable temperature stability instead of the strong acid mentioned. However, this would require an additional work step to complete the stock solution with respect to its Mg content, thereby losing some of the intended rationalization gain. Among the sources of magnesium which, from the practical and economical point of view, are considered available, namely bitters salt (magnesium sulfate) and magnesium nitrate, the bitters salt causes the disadvantage that sulfur is also added to the stock solution, of which it is already difficult to avoid over-concentration, while The composition, which is more acceptable from a compositional point of view, but fairly unfavorably magnesium nitrate is difficult to keep and handle due to its strong hygroscopic properties.

It is therefore an object of the present invention to provide a novel plant nutrient solution containing the macronutrients Mg and P in the desired high molar ratio, but which, when used for the preparation of plant nutrient solutions, does not cause the disadvantages described above.

For this purpose, a plant nutrient solution of the kind initially stated is peculiar in that it is a magnesium phosphate solution having a total water content of 20-45 preferably 35 to 42% by weight and a molar ratio of Mg to P of 0.9: 2-1. 2: 2, preferably 1: 2-1,2: 2, and in addition 25 contains micronutrients, such as Fe, Mn, Zn, Cu, B, Mo and Co, in a sufficient amount to cover its P content. the micronutrient requirement of such a complete nutrient stock solution whose total P content is supplied with said plant nutrient solution, as well as one or more chelating substances in a sufficient amount of chelates to bind the micronutrients. Consequently, the plant nutrient solution conveniently contains micronutrients in an amount which according to the invention exceeds 5% of the P weight and is suitably of the order of 10-12% of the P weight. The plant nutrient solution proposed according to the invention has surprisingly good stability even at high concentration and over-content of Mg, ie. at a molar ratio of Mg to P exceeding 1: 2. At the high concentration, additional benefits are obtained in the form of reduced transport costs and reduced packaging costs per unit. quantity unit plant nutrition. In addition, the plant nutrient solution contains both required Mg and P and required micronutrients in mutually matched quantities, significant rationalization gains are obtained in preparing stock solutions without detrimentally affecting the degree of freedom of their composition.

The invention also relates, as mentioned, to a process for the preparation of a plant nutrient solution containing macro nutrients consisting of Mg and P and containing micronutrients such as Fe, Mn, Zn, Cu, B, Mo and Co, and one or more chelating compounds in a for binding the micronutrient as chelate sufficient amount. In the process of the invention, a plant nutrient solution having a high concentration and high molar ratio of Mg to P is prepared without the risk of precipitation of heavily soluble, as plant nutrient inert salts in the preparation and subsequent handling and use of the plant nutrient solution. The process according to the invention is essentially characterized in that the micronutrient and one or more chelating substances are added to a slurry of magnesium oxide in water, after which phosphorous in the form of phosphoric acid and optionally further slurry of magnesium oxide in water, for which preparation of the magnesium oxide slurry is added. and optionally diluting uses water to a final water content in the plant nutrient solution of 20-45, preferably 35-42% by weight, and the amount of magnesium oxide and phosphoric acid is adjusted in such a way as to obtain in the solution a molar ratio of Mg and P of 0, 9-1.2: 2, preferably 1-1.2: 2. It is thus within the scope of the invention that the magnesium oxide is used in said slurry in a pre-cured form. The amount and composition of the micronutrient is hereby preferably selected in such a way as to cover the micronutrient requirement of a complete full fertilizer whose total P content and preferably also 35 Mg content is added using the plant nutrient solution described above. Conveniently, micronutrients are added in an amount greater than 5% by weight of the plant nutrient solution P content, preferably in the range of 10-12% by weight P.

In one embodiment of the process according to the invention, 10-20% of the total amount of magnesium oxide slurry is initially used while the residue is added after 5 or simultaneously with the addition of phosphoric acid.

Of the micronutrients, ie. mainly Fe, Mn, Cu, B, Zn, Mo and Co, which the plants need only in very small amounts, according to one embodiment of the invention one or more, with the exception of boron and molybdenum, is added in the form of a sulfate. Boron is preferably added in the form of boric acid, while a suitable molybdenum composition of the invention is ammonium molybdate. A preferred alternative form of iron is a complex of iron with the trisodium salt of hydroxyethyl ethylenediaminetriacetic acid, which complex is a commercially available product.

As a chelating substance or substances, any substance used in other contexts can be used to form chelates with micronutrients in various fertilizers or plant nutrients. Examples 20 of such substances are ethylenediaminetetraacetic acid (EDTA) in the form of free acid, hydroxyethylethylenediaminetriacetic acid (HEEDTA) in the form of free acid or the trisodium salt, citric acid, tartaric acid, nitrilotriacetic acid and other chelating agents having good solubility in acidic environment. Hereby it may be advantageous to use specially soluble chelating agents or to supplement a less soluble chelating agent with a more easily soluble one. Thus, in cases where EDTA is used as a chelating agent, it may be appropriate to use HEEDTA at the same time whereby the proportion of EDTA, based on the weight of the mixture, is conveniently at most 2/3.

The amount of chelating substance or substances is adjusted to the amount of micronutrients in such a way that the latter can be completely bound in the form of chelates. The amount of micronutrients, in turn, is adjusted to each other and to the amount of P in such a way as to satisfy the conditions that usually prevail between micronutrients among themselves and between P and full fertilizers.

The invention will now be further illustrated by some embodiments.

Example 1

A plant nutrient is prepared at which 100 kg of solution used: 5 45 kg 85% s H3PO4 8.3 kg MgO (56.7% Mg) 6.9 kg Fe-HEEDTA complex (9% Fe) 2.4 kg EDTA (in acid form) 2.18 kg micro-mixture without Fe of which 0.82 kg of MnSO4 (32.5% Mn) 0.48 kg of CuSO4 (25.4% Cu) 0.57 kg of H3B03 (17.5% B) 0.27 kg of ZnSO4 (22.7% Zn) ) 0.022 kg (NH 4) 6 Mo? 024 (54.3% Mo) 0.019 kg. CoSO 4 (21.0% Co) 2.18 kg 35.22 kg H2 O 100.00 kg

MgO is worked up to a slurry with twice the amount of water.

Ca. 20% of the slurry was placed in a stirred and water-cooled reaction vessel, to which was added the remaining amount of water, the Fe-HEEDTA complex and the micro-mixture with stirring and cooling.

After 4 minutes, the phosphoric acid was added and the remainder of the MgO slurry was added at such a rate that a homogeneous mixture was obtained and the temperature did not exceed 85 ° C.

After all the MgO was added, stirring and cooling were continued for 15 minutes, after which the product was drained after bottling.

The resulting product had a content of 41.97 wt% H 2 O, 12.06 wt% P and 4.7 wt% Mg corresponding to a molar ratio Mg: P of 1.0: 2.

7 15QS37

Example 2

A plant nutrient was prepared in the same manner as in Example 1, but so that per 100 kg of solution was used: 5 45 kg 85% H3 PO4 9 kg MgO (56.7% Mg) 6.9 kg Fe-HEEDTA complex (9% Fe) 2.4 kg EDTA (in acid form) 2.18 kg micro-mixture without Fe (see Example 1) 10 34.52 kg H2 O 100.00 kg

The resulting product had a content of 41.27 wt% H 2 O, 12.06 wt% P and 5.10 wt% Mg corresponding to a molar ratio Mg: P of 1.08: 2.

Example 3

A plant nutrient was prepared in the same manner as in Example 1, but so that per 100 kg of solution were used: 45 kg of 85% H 3 PO 4 8.3 kg MgO (56.7% Mg) 5.3 kg of micro-mixture of which 3.12 kg FeSO 4 (20.1% Fe) 0.82 kg MnSO 4 (32, 5% Mn) 0.48 kg CuSO4 (25.4% Cu) 0.57 kg H3B03 (17.5% B) 0.27 kg ZnSO4 (22.7% Zn) 0.022 kg (NH4) 6Mo7024 (54, 3% Mo) 0.019 kg CoSO 4 (21.0% Co) 5.3 kg 30 3.0 kg EDTA (in acid form) 2.0 kg citric acid 36.4 kg H2 O 8 150S37

The resulting product had a content of 43.2 wt% 1 50, 12.06 wt% P and 4.7 wt% Mg corresponding to a molar ratio Mg: P of 1: 2.

The solutions prepared according to the examples were found to be very stable and withstand temperatures below -30 ° C without salting out.

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Claims (4)

150637 1. <· Plant nutrient solution containing macronutrients consisting of Mg and P and intended for use in the preparation of a liquid, with regard to its content of plant nutrients 5 such as N, P, K, S, Ca, Mg, Fe, Mn, Zn , Cu, B, Mo, and Co complete nutrient stock solution for nutrient enrichment of irrigation water, characterized in that the plant nutrient solution is a magnesium phosphate solution with a total water content of 20-45, preferably 35-42% by weight and a mole ratio of 10 Mg to P of 0.9-1.2: 2, preferably 1-1.2: 2, and furthermore, micronutrients such as Fe, Mn, Zh, Cu, B, Mo and Co contain a sufficient amount in relation to the P content of the solution to cover the micronutrient requirement in such a complete nutrient stock solution whose total P content is supplied with the plant nutrient solution, as well as one or more chelating substances, in a sufficient amount of chelate to bind the micronutrients. Plant nutrient solution according to claim 1, characterized in that it contains micronutrients in an amount of 20 which exceeds 5% of the P weight, suitably in an amount of about 10-12% of the P weight. A process for preparing a plant nutrient solution as claimed in claim 1 with macronutrients consisting of Mg and P and containing micronutrients such as Fe, 25 Mn, Zn, Cu, B, Mo and Co and one or more chelating agents in one for the binding of the micronutrient as a chelating amount, characterized in that the micronutrient or chelating agent (s) is added to a slurry of magnesium oxide in water, whereupon phosphorus is added in the form of phosphoric acid and, if necessary, additional slurry of magnesium oxide in water, whereby to prepare the magnesium slurry and possibly dilution water is used for a final water content of the plant nutrient solution of 20-45, preferably 35-42% by weight and the amount is adjusted. of magnesium oxide and phosphoric acid in a manner such that a molar ratio of Mg to P of 0.9-1.2: 2 is used, preferably 1-1.2: 2.