FI112938B - Sour potassium nitrate - Google Patents

Description

112938

5 ACID POTASSIUM NITRATE

The present invention relates to solid, acidic potassium nitrate, whereby the chemical properties of hard alkaline water, such as water pH and bicarbonate content, can be better adjusted to the plant growth requirements. The invention also relates to a watering plant irrigation solution prepared from this product.

BACKGROUND ART Plants need heat and sunlight, water and nutrients to grow. The growth factor of plants is determined by the growth factor that is the least in relation to their need. In order to guarantee the growth potential, the plants are provided with sufficient water and nutrient supply.

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Except for sufficient water supply, plant growth can be ensured by ensuring proper water supply, ·. : problematic. This is particularly problematic when the soil is calcareous and alkaline. In this case, the raw water also contains dissolved calcium and bicarbonate, which makes it alkaline and hard and thus less suitable for watering plants.

Of the various irrigation methods, drip irrigation, where nutrient levels in the irrigation water can be adjusted to meet the • specific needs of the plants of the particular semen, has proven to be - effective in both water and nutrient use. For example, the efficiency of phosphorus in drip irrigation is significantly better than that of 35 fixed phosphorus fertilizers applied as land fertilizer. Drip irrigation has become a popular crop in Mediterranean countries, for example.

In drip irrigation, the use of hard and alkaline water can cause technical problems, for example, with calcium carbonate 40 (CaCO 3) forming deposits on irrigation piping walls 2 112938 5 and nozzles. This problem is particularly pronounced in sub-surface drip irrigation (SDI).

In practice, this problem has been solved by dissolving the precipitates formed in the pipelines with strong mineral acids such as nitric acid or phosphoric acid. As strong liquid acids, they are not only difficult to handle but also dangerous to humans and the environment. Also, solid inorganic acids such as solid phosphoric acid hemihydrate (melting point 29.3 ° C, CRH 9% RH) are not suitable because of their unfavorable physical properties.

From WO 01/25168 a solid water soluble fertilizer composition is known which, in addition to the fertilizers, contains phosphate free organic acid for adjusting the pH of the water. However, in nutrient solutions, organic acids can act as microbial nutrients, forming a mucus-like microbial growth that clogs the nozzles of irrigation equipment. Organic substances nor are they compatible with oxidizing agents such as ···. potassium nitrate. Since organic acids are expensive 25 and do not contain nutrients essential for plants, they do not. . the use is merely unnecessary.

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··· 'The addition of solid ureaf osphate to irrigation fertilizers is: ··; has been a clear improvement in preventing the formation of precipitates.

The addition of nitrogen and phosphorus as nutrients to the solution also enables the pH of the solution to be acidified and precipitated; formation. Such a solution has been proposed by R.L. Mikkelsen (Soil Sci.Soc.Am.J. 1987 51: 2 464-468).

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ZA 7507914 (Triomf Fertilizers Ltd) discloses a process for preparing a solid, acidic NPK compound fertilizer based on urea, concentrated phosphoric acid solution and potassium nitrate.

40 3 1 .38 5 It is known that the pH of a working solution suitable for irrigation fertilization is preferably 5-7. However, to be able to prepare such a working solution, the farmer should be aware of the pH and buffering capacity of the raw water, the urea phosphate concentration of the solution and the effect of other fertilizers in the solution on the pH of the final working solution. A further complication is that the pH of the same fertilizer, for example monoammonium phosphate, may vary depending on the production process of the product and the raw materials used.

15 Most irrigated plants need relatively most potassium, slightly less nitrogen and least phosphorus in their primary nutrients (N, P, K). For this reason, potassium nitrate is an ideal nutrient salt for use as a source of nitrogen and potassium in irrigation fertilizers.

20: The most common potassium salt used in both horticultural and glasshouse cultivation is potassium, ·. : lithium nitrate. Potassium chloride is used less for its disadvantages / ··. due to the high chloride content. Potassium sulphate 25, on the other hand, cannot be used if it is rich in raw water. . calcium, which precipitates as calcium sulphate or gypsum.

Potassium nitrate is used either alone or in a compound fertilizer; * ·; with other nutrient salts to provide the desired nutrient ratios. It is also common for farmers to make their own working solutions using different fertilizers.

For good growth, the plant needs not only water and N, P and K, but also secondary and micronutrients. It is known 35 that the availability of both phosphorus and micronutrients is highly pH dependent (Kluwer Academic Publishers, Fertilizer Manual, 1998, pp. 24-26).

The plant is most comfortable in an environment with a pH of about 5-7. 40 Within this pH range, most nutrients are in a form suitable for use by plants. In alkaline environment, precipitation of cundar and micronutrients as phosphates or other compounds occurs. At low pH (pH <5), for example, the concentration of aluminum in the soil fluid increases sharply. This has adverse effects on the roots of the plants. Generally, a pH range of 5.5 to 6.5 is preferred for root growth; which in turn is 10 basic preconditions for plant growth. (Taiz L., Zaiger E., Plant

Physiology, 105, 1991; Kluwer Academic Publishers, Fertilizer Manual, 1998, pp. 24-26).

DISCLOSURE OF THE INVENTION The present invention relates to solid, acidic potassium nitrate, which can better adjust the pH and bicarbonate content of hard, alkaline water to meet plant growth requirements. The acidic potassium nitrate of the invention contains less than 15% by weight of urea phosphate. The invention also relates to a solution containing: 20 mg potassium nitrate, up to 0.3% (w / w). The acid potassium nitrate used according to the invention may be a mixture of crystalline substances, a granular product.

, ···. The acidic potassium nitrate of the invention may be prepared, for example, by simply mixing crystalline urea phosphate and crystalline potassium nitrate at desired weight ratios.

·· Potassium nitrate acidified with urea phosphate therefore has a positive effect on the solubility of both phosphorus and secondary and micronutrients and thus enhances the ability of plants to utilize these nutrients. However, irrigation solutions containing it are not too acidic to be used, for example, in drip irrigation. Also, when using the product according to the invention, no separate acid addition devices are required.

Generally, for irrigation fertilization, a stock solution of about 10% (w / w) is first prepared and then further diluted to a working solution of about 40 0.01-0.3% (w / w). The acidic potassium nitrate of the invention containing 2-15% (w / w) urea phosphate can also be used in dilutions of 0.01-0.3% (w / w), preferably 0.05-0. 3% (w / w) dilutions at pH 7-9 of available raw water and 175-350 ppm HCO3 bicarbonate. Particularly preferred is the use of acidic potassium nitrate with medium hard water having a pH of 7-9 and a bicarbonate content of 175-250 ppm HCl 3.

However, the use of the product of the invention for irrigation fertilization purposes is not limited to hard water, but is also suitable for use with soft water, provided that a good dilution ratio is taken into account.

The pH of the solution used for drip irrigation can be adjusted with 0.01 to 0.3% aqueous solution of potassium nitrate acidified with urea phosphate to a pH range where no CaCO 3 precipitates.

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Other conventional fertilizers, such as urea, may be used in combination with the product for irrigation. : and / or monoammonium phosphate (MAP), while taking into account • t. ···. that the total nutrient concentration of the irrigation solution is less than 25 <0.3% (w / w).

· · · In fertilizer compositions, the proportion of potassium nitrate varies, but ··· 'is typically about half or more than half of the total amount of fertilizer ·; ··: Addition of urea phosphate to potassium nitrate, i.e. acidification of potassium nitrate, thus makes it possible to adjust the pH of conventional fertilizer solutions used in irrigation fertilizers (nutrient content <0.3%; solids KN03 over '50% (w / w)). The acidic potassium nitrate solution automatically adjusts the pH of the working solution wherever medium hard water is available. Such areas are the Mediterranean countries, South America and Australia, for example.

Due to its low phosphorus content, the use of acidic potassium nitrate 40 is possible even when the plant's phosphorus requirement is low. If, on the other hand, the plant needs more phosphorus, any phosphorous fertilizer suitable for irrigation fertilization may be used.

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Drip irrigation is one of the most effective forms of fertilization. However, problems may occur when al-10 alkaline and hard water forms deposits (e.g., Ca-CO 3) on the piping wall walls and nozzles. Particularly the problem is highlighted in sub-surface drip irrigation (SDI). Aqueous solutions of potassium nitrate acidified with urea phosphate 0.01-0.3% (w / w) can be used to adjust the pH of raw water

15 water hardness to the area where no CaCO 3 precipitate is formed and thus the problems caused by humus and mucus bacterial coatings are eliminated.

... · Thus, as a solution to the above problems, it has been found 20 to add urea phosphate among potassium nitrate. Urea Phosphate: Due to the sufficient acidity, the amounts of urea phosphate used are small and do not limit the use of conventional fertilizer compositions in irrigation fertilization.

Table 1 shows the acid potassium according to the invention. a nutrient composition of raate when containing urea phosphate; * Amount varies.

: ·· Table 1. Nutrient Ratios of Acid Potassium Nitrate 30, Mixture Mixture Relative; p -% UP and p -% KNO3 N - P205 - K20 N - P205 - K20 '' UP_KNO3_N_P2O5 K20 N_P2O5 K20 15_85_14,3 6, 6 39, 1 1, 0 0,5 2,7 10_90_14,1 4,4 41 , 4 1.0 0.3 2.9 5_95_ 13.9 2.2 43.7 1, 0 0.2 3.1 0_ | l00 _113, 7 jo, 0 | 46.0 | l, 0 | o, 0 | 3,4

Other benefits of acid potassium nitrate are good physical quality, since both components have little or no moisture absorption.

The corrosive effect of urea phosphate metals (e.g., copper and zinc metals) is also significantly less than that of the mineral acids used for similar purposes. The advantage of urea phosphate is enhanced when the solution is rich in potassium nitrate. (Corros.Sci. (1976), 16 (8), 485-98).

Compared to other mineral acids, phosphoric acid has a strongly buffering nature. In practice, this means that when urea phosphate acidified potassium nitrate is added, the pH of the alkaline water (e.g. pH 8) can be quickly and efficiently lowered to the desired range (<pH 7), but the pH remains within the range 5-7 because of the buffer effect.

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For the adjustment of the pH of particularly hard water (e.g., 250-350 ppm HC03), either stronger concentrated solutions of acidic potassium nitrate (e.g. 0.2-0.3% (w / w)) or relatively more urea phosphate may be used. acidic potassium nitrate.

25th . The invention is further defined in claims 1-10.

: ·; The following examples are intended to illustrate the invention without, however, limiting it in any way.

" ' ; Example 1

Comparison of acidic potassium nitrate solutions Two series of fertilizer solutions were prepared in deionized water, one containing potassium nitrate acidified with urea phosphate and one with mono-ammonium phosphate. The pH of the solutions was measured. The measurement results are shown in Table 2.

40 112 * 30 8 5 Table 2.

Fertilizer- Potassium Nitrate- Potassium Nitrate Concentration of potassium nitrate solution (90%) and (90%) and monoamerate, urea phosphate monium phosphate (100%), w-% (10%), (10%), _______pH__pH___pH_ 0.1__3, 22__5,59__6, 87_ 1.0 __2,35__4,83__6, 85_ 10.0 | 1.55 [4.30 1 6, 82_ 10 The results show that when the same amount of monoammonium phosphate and urea phosphate are added to potassium nitrate, the pH change with urea phosphate acidified potassium nitrate is significantly greater than that of monoammonium phosphate with acidified potassium nitrate.

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Example 2

Effect of acidic potassium nitrate on medium hard water 1. 'Synthetic, medium hard water with a bicarbonate sodium content of 175 ppm HC03, a calcium content of 82 ppm Ca and a pH of 7.2 was added by adding 241 mg of sodium bicarbonate and 160 mg of calcium chloride to one liter of ion exchange.

! A series of solutions of five different potassium nitrates acidified with different amounts of urea phosphate were prepared in the above-mentioned synthetic medium-hard water. Control solutions were prepared from pure potassium nitrate. The pH of the solutions was measured. The measurement results are shown in Table 3.

9 1: 30 5 Table 3

Fertilizer 0.05% 0.1% 0.2% 0.3% Composition Nutrient Nutrient Nutrient Nutrient Solution Solution Solution __pH__pH__pH__pH_ 15% UP, 85% KN03 7,0__7 ^ 0__6? _4__5, 6 12% UP , 88% KN03 7.0 * __-__ 6 ^ 5__M) _ 8% UP, 92% KN03 __-__ 6 ^ 9__6 ^ 5_ 5% UP, 95% KN03 __-__-__ 6 ^ _9_ 2% UP, 98% KN03 __ = __ = __ 7.0 * 0% UP, 100% KN03 [7.8 | 7.9 1 8.1 L 8.1 (* pH of raw water about 7) '··· Example 3; Effect of Acid Potassium Nitrate on Moderate Hard Water '· Synthetic Moderate Medium Water with Bicarbonate Content: 250 ppm HCO3, Calcium Content 82 ppm Ca and pH 7 was prepared by adding 344 mg of sodium bicarbonate and 228 mg of 15 mg of calcium chloride to one liter of ion exchange.

A series of four solutions of potassium nitrate acidified with various amounts of urea phosphate were prepared in this water. Solution concentrations ranged from 0.1% to 0.3%. Reference solutions containing potassium nitrate alone were prepared. The pH values of the solutions and the results are shown in Table 4.

112-38 10 5 Table 4.

Fertilizer Composition 0.1% 0.2% 0.3% Nutrient Nutrient Solution Solution Solution __pH__pH__pH_ 15% UP, 85% KN03 __; Λ_0__6 ^ 6__6 ^ 1_ 12% UP, 88% KN03 __ = __ 6 ^ 7__6 ^ 4_ 8% UP, 92% KN03 __: _ 7,0__6 ^ 7_ 5% UP, 95% KN03 __ = __-__ 7.0 0% UP, 100% KN03_ | 8,0_ | 8.0_8.0_

Example 4

Effect of acidic potassium nitrate on fairly hard water '····' 10. '* Synthetic, relatively hard water with a bicarbonate content of 300 ppm HCl 3, a calcium content of 99 ppm Ca and a pH of 7 was prepared by the addition of 413 mg / liter sodium bicarbonate and 274 mg; mg / liter of calcium chloride in deionized water.

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Four different potassium nitrates acidified with different amounts of urea phosphate; 0.2-0.3% solutions of this water in this water were made. Control solutions containing potassium nitrate alone were prepared. The pHs of the solutions were measured and the results are shown in Table 5.

20: Table 5! Fertilizer composition 0.2% 0.3% nutrient solution nutrient solution ___ Pä_ 15% UP, 85% KN03__6 ^ 8__6 ^ 5_ 12% UP, 88% KN03__6j_9__6 ^ 27_ 8% UP, 92% KN03__I__6j_9_ 5% UP, 95% KN03 __-__ V_ 0 % UP, 100% KN03_I 7,8_7,8_11 112938 5 Example 5

Effect of acidic potassium nitrate on fairly hard water

Synthetic, fairly hard water with a bicarbonate content of 330 ppm HC03, a calcium content of 109 ppm Ca and pH 7 was prepared by adding 454 mg / liter of sodium bicarbonate and 301 mg / liter of calcium chloride to deionized water.

0.05-0.3% solutions of this potassium nitrate in two different amounts of urea phosphate acidified in water were prepared. Control solutions containing potassium nitrate alone were prepared. The pH of the solutions was measured and the results are shown in Table 6.

Table 6 '·. · 20 ____ it <: Fertilizer composition- 0.05% 0.2% 0.3% tum nutrient nutrient nutrient solution

\ | pH pH pH

15% UP, 85% KN03 7.1 6.9 6.7 »-------------------------------- 12 % UP, 88% KN03 -___ 7jl0 ___ 6 ^ 5_ ·. . 0% UP, 100% KN03 7, 6 7.9 8.0! »H On the basis of the tests carried out, it can be said that the acidity of potassium nitrate was able to control different hardnesses: water (pH about 7), acidity for watering plants (25 pH range. Potassium nitrate-only reference solutions) unexpectedly raised the pH of the water to 8.

Claims (10)

1. An aqueous solution of solid potassium nitrate, acidified with urea phosphate, intended for irrigation of plants, characterized in that it consists of 0.01-0.3% by weight of acidic potassium nitrate and hard alkaline water. An aqueous solution of acidic potassium nitrate according to claim 1, characterized in that it contains hard alkaline water whose pH is 7-9 and whose bicarbonate content is 175-350 ppm HC03. An aqueous solution of acidic potassium nitrate according to claim 2, characterized in that it contains hard alkaline water whose pH is 7-9 and whose bicarbonate content is 175-250 ppm HC03. 15 An aqueous solution of acidic potassium nitrate according to claim 1, characterized in that the pH of the solution is 5-7. An aqueous solution of acid potassium nitrate according to claim 4, characterized in that the pH of the solution is 6-7. : An aqueous solution of acidic potassium nitrate according to claims 4 and 5, characterized in that its bicarbonate content is <150 ppm HC03. 25 An aqueous solution of acidic potassium nitrate according to claim 1 for use in drip irrigation. An aqueous solution of acid potassium nitrate according to claim 1 for use with other nutrient salts. 9. A solid acidic potassium nitrate for adjusting the chemical properties of a hard alkaline water and for preparing an aqueous solution for watering plants, characterized in that it contains 85-98% by weight potassium nitrate and 2-15% by weight. % urea phosphate. 11: 38 An acidic potassium nitrate according to claim 9, characterized in that it can contain desiccant.