JP2000302583A - Slow-release liquid fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slow-release liquid fertilizer which exhibits a higher fertilizer effect and has excellent storage stability by producing the fertilizer so that it consists of a cyanamide acidic aqueous solution containing a dicyandiamide and the ratio of the dicyandiamide content to the total content of the cyanamide and dicyandiamide in the solution is within a specified range and in particular, the calcium ion concentration in the solution is equal to or lower than a specified concentration value. SOLUTION: This fertilizer is a cyanamide acidic aqueous solution containing dicyandiamide. In the solution, the ratio of the dicyandiamide content to the total content of the cyanamide and dicyandiamide is 1-20 wt.% and the calcium ion concentration is <=1.00 ppm. The production process of the fertilizer comprises: agitating calcium cyanamide in water and blowing gaseous carbon dioxide into the liquid agitated, to precipitate calcium as calcium carbonate and to filter the resulting liquid; thereafter adjusting the pH of the filtrate to about 4-6 with an inorganic acid such as mineral acid or organic acid such as acetic acid to form a stabilized cyanamide acidic aqueous solution; adding a dicyandiamide to the cyanamide acidic aqueous solution to adjust the dicyandiamide content; and further adding an ion exchange resin to the solution, agitating them and thereafter removing the ion exchange resin from the solution, to reduce the calcium ion concentration in the solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a slow-release liquid fertilizer.

[0002]

2. Description of the Related Art Hitherto, there has been proposed a liquid fertilizer having a fertilizing effect equivalent to that of lime nitrogen and containing cyanamide as a main component and which is easy to spray (Japanese Patent Application Laid-Open No. 9-328363). Although this liquid fertilizer has excellent fertilizing effect, it is still unsolved that nitric acid is generated quickly in cultivation of agricultural products, and it changes over time during storage, and the fertilizing effect is not sufficiently obtained. Met.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above, and it is an object of the present invention to exhibit a higher fertilizing effect by slowing down liquid fertilizer and to improve storage stability. It is to provide an excellent liquid fertilizer.

[0004]

That is, the present invention comprises a cyanamide acidic aqueous solution containing dicyandiamide, wherein the dicyandiamide is present in an amount of 1 to 20% by weight based on the total amount of cyanamide and dicyandiamide. It is an effective liquid fertilizer, particularly characterized in that calcium ion is 100 ppm or less.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The present invention is a slow-acting liquid fertilizer comprising a cyanamide acidic aqueous solution in which the production of nitric acid in soil is suppressed by the presence of more dicyandiamide than before. What is important in the present invention is that the content of dicyandiamide in the acidic aqueous solution of cyanamide is 1 to 20% by weight based on the total amount of cyanamide and dicyandiamide. If the content of dicyandiamide is less than 1% by weight, the production of nitric acid is rapid, and the fertilizer runs off, and a sufficient fertilizing effect cannot be obtained similarly to the conventional liquid fertilizer containing cyanamide as a main component. On the other hand, if the content of dicyandiamide exceeds 20% by weight, the rate of nitric acid generation is excessively suppressed, so that nitric acid cannot be absorbed during the growing period. Can not be obtained. The dicyandiamide content in the present invention is 0.5% of that of the conventional liquid fertilizer containing cyanamide as a main component.
It is specific as compared to about weight%.

[0007] The calcium ion concentration of the liquid fertilizer of the present invention is preferably 100 ppm or less, particularly preferably 30 ppm or less. A conventional liquid fertilizer containing cyanamide as a main component contains a large amount of calcium ions, so that cyanamide changes to dicyandiamide, urea, ammonia, and the like during storage, and a sufficient fertilizer effect may not be obtained. In the present invention, such a problem is solved by reducing the calcium ion contained in the acidic aqueous solution of cyanamide to 100 ppm or less with an ion exchange resin or the like, and a high fertilizing effect can be obtained even after several years. .

The concentration of cyanamide in the liquid fertilizer of the present invention is preferably 5 to 50% by weight from the viewpoint of use and stability. Further, the liquid fertilizer of the present invention is compounded by adding a phosphorus component such as phosphates such as phosphoric acid and potassium phosphate, a potassium component such as potassium chloride and potassium sulfide, and a trace element such as magnesium, boron and manganese. It can also be used as a liquid fertilizer.

The method of using the liquid fertilizer of the present invention will be described. For example, in the case of a liquid fertilizer containing 15% by weight of cyanamide, the original fertilizer such as paddy rice, open-field vegetables, greenhouse horticulture, etc. is diluted 5 to 50 times during normal application and 300 to 500 times when applied simultaneously with irrigation. The liquid thus obtained is sprayed with a sprinkler, a boom sprayer, an irrigation tube or the like.
On the other hand, in the case of topdressing of open-field vegetables, greenhouse horticulture, fruit trees, etc.
An undiluted solution or a solution diluted 2 to 20 times is peeled off from the roots and sprayed or sprayed on ridges, ridge shoulders and the like.

[0010] The liquid fertilizer of the present invention can be produced using cyanamide, lime nitrogen, urea and the like as raw materials. For example, when manufacturing from lime nitrogen, lime nitrogen is stirred in water, and carbon dioxide gas is blown in to precipitate calcium as calcium carbonate. After filtration, the pH is adjusted to 4 to 6 with an inorganic acid such as a mineral acid or an organic acid such as acetic acid. Adjusted to a stable level to obtain a stabilized cyanamide acidic aqueous solution. Next, dicyandiamide is added to the acidic aqueous solution of cyanamide or denatured by heating to adjust the dicyandiamide content within the range of the present invention. Further, when the above-mentioned acidic aqueous solution of cyanamide is produced, it can be carried out by raising the reaction temperature in a step of blowing carbon dioxide gas to convert calcium into calcium carbonate.

The calcium ions can be reduced to 100 ppm or less by adding an ion-exchange resin to the above-prepared acidic aqueous solution of cyanamide and removing the ion-exchange resin after stirring, or by adding the above-mentioned liquid fertilizer to the ion-exchange resin. By passing through a column packed with. As the ion exchange resin, a cation exchange resin such as a carboxylic acid type and a sulfonic acid type is used.

[0012]

The present invention will be described more specifically below with reference to examples and comparative examples. Examples 1-5 Comparative Examples 1-2 Powdered lime nitrogen (manufactured by Denki Kagaku Kogyo KK: 21% nitrogen)
130 parts by weight were added to 250 parts by weight of water, carbon dioxide gas was blown in for 6 hours while stirring at room temperature, and the precipitate was removed by filtration. The pH was adjusted to 5 with acetic acid, and the cyanamide concentration was 1
There was obtained 100 parts by weight of a 5.9% by weight and 0.09% by weight of dicyandiamide aqueous solution of cyanamide acid. To 100 parts by weight of the obtained aqueous acid solution of cyanamide, 100 parts by weight of powdery dicyandiamide shown in Table 1 was added and stirred to produce various liquid fertilizers. Table 1 shows the analysis values of the liquid fertilizer. The calcium ion concentration of these liquid fertilizers was 300
５００500 ppm.

Example 6 The concentration of calcium ion produced in Example 1 was 342 p.
5 parts by weight of an ion exchange resin (Amberlite IRC-50) was added to 110 parts by weight of a liquid fertilizer at pm, and the mixture was stirred and filtered to remove calcium ions, and the cyanamide concentration was 15.6.
100 parts by weight of a liquid fertilizer having a weight percentage of 0.57% by weight of dicyandiamide, a calcium ion concentration of 12 ppm and a pH of 4.8 were obtained. This was subjected to a storage stability promotion test in which it was stored at 40 ° C. for 2 months (corresponding to about 2 years at ordinary temperature), and the analysis value of the liquid fertilizer was measured. Table 2 shows the results.

Reference Example 1 The concentration of calcium ion produced in Example 1 was 342 p.
A storage stability test was conducted in which 100 parts by weight of pm liquid fertilizer was stored at 40 ° C. for one month, and its components were measured. Table 2 shows the results.

[0015]

[Table 1]

[0016]

[Table 2]

The liquid fertilizer produced as described above was subjected to the following mineralization test. The results are shown in Table 3 and FIG.

(Mineralization test) In a container, 30 grams of dry soil (medium-coarse brown lowland soil: 0.93 kilograms per liter on site) and liquid fertilizer diluted with 100 times pure water as nitrogen 20 mg was added and mixed, pure water was further added to adjust the maximum water volume to 60%, and the mixture was allowed to stand in a thermostat at a temperature of 30 ° C., followed by shaking with 150 ml of a 1 NK ₂ SO ₄ aqueous solution for 30 minutes, followed by filtration. Was measured with an ion meter.

[0019]

[Table 3]

Next, the following cultivation tests were conducted using some of the liquid fertilizers produced in the examples and comparative examples. Table 4 shows the results.

(Cultivation test) Target crop: Kyabetsu Cultivation conditions: Open-field cultivation Cultivation area: 1 area 10 square meters (compartment 3
Liquid fertilizer application period: One week before planting Application amount: Water is added to 2 liters of liquid fertilizer to make the total volume 20 liters, sprayed over 10 square meters, and 1.25 kg of lime superphosphate is further added.
Acid Kali 0.4kg, Formic Lime 1.0
Kilograms were sprayed and mixed well with soil. Harvest survey period: 4 months after planting

[0022]

[Table 4]

[0023]

EFFECT OF THE INVENTION The slow-release liquid fertilizer of the present invention has a higher fertilizing effect because it is slow-released compared to the conventional liquid fertilizer containing cyanamide as a main component, and has excellent storage stability. It is a thing.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the nitrate production rate in soil and the dicyandiamide content in liquid fertilizer.

Claims (2)

[Claims] 1. An aqueous cyanamide solution containing dicyandiamide, wherein the dicyandiamide is present in an amount of 1 to 20% by weight based on the total amount of cyanamide and dicyandiamide.
A slow-acting liquid fertilizer, characterized in that: 2. The slow-release liquid fertilizer according to claim 1, wherein the calcium ion is 100 ppm or less.