JP4638844B2 - Agricultural materials - Google Patents

Description

The present invention relates to agricultural materials.

In farmlands that contain a relatively large amount of cadmium, when crops such as paddy rice and vegetables must be cultivated, there is an interest in how to suppress the absorption of cadmium into crops. Conventionally, in paddy rice cultivation, a method for solving the problem by water management of paddy fields and the use of lime nitrogen has been proposed (Patent Document 1), but there is still room for improvement.
Japanese Patent No. 3688274

An object of the present invention is to provide an agricultural material that is more excellent in the effect of suppressing the absorption of cadmium into agricultural crops.

The present invention is an agricultural material comprising a composition containing light-burned magnesia, phosphoric acid or a salt thereof, and lime nitrogen. In the present invention, (1) light calcined magnesia is a calcined product of magnesium carbonate at 700 to 900 ° C., and (2) at least one phosphoric acid or a salt thereof selected from phosphoric acid, sodium phosphate and calcium phosphate (3) further containing an organic acid or a salt thereof; (4) at least one organic acid or a salt thereof selected from lignin sulfonic acid, citric acid, gluconic acid and sodium salts of these acids; be species, (5) content, light burned magnesia is 60 to 90 wt%, 0.5 to 15% by weight phosphoric acid or a salt thereof as _P 2 _{O 5,} lime nitrogen 5 to 40 wt%, It is preferable to have at least one embodiment selected from the fact that the organic acid or a salt thereof is 6% by mass or less (including 0%).

Agricultural materials that are even more effective in suppressing the absorption of cadmium into crops are provided.

Lightly burned magnesia has the property of hydraulically in the presence of phosphoric acid or a salt thereof, and has the action of capturing and fixing cadmium present in soil when sprayed on agricultural land. Lightly burned magnesia can be produced by firing magnesite (magnesium carbonate) produced in Shuen district of Liaoning Province, China, seawater magnesia etc. using bittern in seawater at 700 to 900 ° C., for example. From the viewpoint of availability, a fired product of 700 to 900 ° C. of magnesium carbonate is preferable. The average particle size is preferably 0.01 to 0.3 mm.

Phosphoric acid or its salt functions as a hydraulic reaction agent for light-burned magnesia. For example, phosphoric acid, sodium phosphate, calcium phosphate and the like. Sodium phosphate includes sodium metaphosphate, acidic sodium metaphosphate, sodium pyrophosphate, acidic pyrophosphate sodium, tripolyphosphate sodium, etc., and calcium phosphate includes acidic calcium phosphate, dicalcium phosphate, tricalcium phosphate, calcium phosphate There is magnesium. Among these, at least one selected from phosphoric acid, sodium phosphate and calcium phosphate is preferable. Examples of substances containing these phosphoric acids or salts thereof include yodophosphorus, superphosphate lime, and heavy superphosphate lime, which can be used. “Yorin” is preferable from the viewpoint of availability. “Yorin” is a phosphate fertilizer produced by melting a mixture of phosphate ore containing phosphoric acid and lime and, for example, serpentine containing silicic acid and magnesium at about 1400 ° C. and then cooling. .

As lime nitrogen, generally available lime nitrogen is sufficient, and calcium cyanamide (CaCN ₂ ) is a main component, and quick lime (CaO), slaked lime (Ca (OH) ₂ ), carbon (C) and the like are subcomponents. are known in a variety of compositions, both as long as it contains more than 40 mass% as CaCN ₂ it can be used. The particle size is preferably 0.01 to 0.3 mm in average particle size when lightly-burned magnesia, phosphoric acid or a salt thereof, and an organic acid or a salt thereof to be contained as necessary are mixed in advance. . On the other hand, when these components are mixed individually or in combination with two or more components and sprayed on the soil at the fertilization site, there is no particular limitation, and a powder with an average particle size of 0.01 to 0.3 mm, an average particle size of 0 Any particle size of .5 to 4.0 mm can be used.

By delaying the hydraulic reaction between light-burned magnesia and phosphoric acid or a salt thereof, the effect of capturing cadmium can be enhanced. Therefore, in the present invention, it is preferable to use a hydraulic reaction retarder comprising an organic acid or a salt thereof. Illustrative examples include humic acid, lignin sulfonic acid, citric acid, tartaric acid, gluconic acid, and sodium, ammonium and calcium salts of these acids. Among these, at least one selected from lignin sulfonic acid, citric acid, gluconic acid and sodium salts of these acids is preferable.

The content, light burned magnesia is 60 to 90 wt%, 0.5 to 15% by weight phosphoric acid or a salt thereof as _P 2 _{O 5,} lime nitrogen 5 to 40 wt%, organic acids or salts thereof 6 mass % Or less (including 0%). When these components do not reach 100% by mass, inorganic carbonates such as sodium carbonate, sodium bicarbonate, ammonium carbonate, and magnesium carbonate, for example, inorganic sulfates such as iron sulfate, magnesium sulfate, aluminum sulfate, and calcium sulfate, such as blast furnace The mixture is filled with appropriate materials such as granulated slag, fly ash, and other calcareous substances and siliceous substances.

An example of the method of using the agricultural material of the present invention is as follows: a method of spraying the agricultural material of the present invention to the soil, a mixture of light-burned magnesia and phosphoric acid or a salt thereof is prepared in advance, and lime nitrogen is added to the soil. Any of the methods of spraying the components constituting the agricultural material of the present invention to the soil at the site, such as a method of spraying on the soil, is possible. The amount used is light burned magnesia consisting of a mixture of light burned magnesia and phosphoric acid or its salt (which may include organic acid or its salt), excluding lime nitrogen, with respect to 100 parts by mass of soil (in terms of dry soil). It is preferable that the powder composition is 0.1 to 0.5 parts by mass, particularly 0.2 to 0.4 parts by mass. It is preferable to make other components other than the light-burning magnesia composing the light-burning magnesia powder composition proportional to the above-mentioned preferred ratio. Lime nitrogen is preferably 0.01 to 0.1 parts by mass, particularly 0.01 to 0.04 parts by mass as CaCN ₂ .

Examples 1-4 Comparative Examples 1-5
Natural magnesium carbonate was calcined at 800 ° C. for 4 hours in an air atmosphere and then pulverized to produce a light calcined magnesia powder (average particle size 0.1 mm). Moreover, commercially available iodine (P ₂ O ₅ as 20% by mass, average particle size 0.1 mm), commercially available heavy perphosphate phosphate powder (P ₂ O ₅ as 44% by mass, average particle size 0.1 mm), Hexametaphosphate sodium (P ₂ O ₅ content 67% by mass), tripolyphosphate sodium (P ₂ O ₅ content 57% by mass), and an organic acid or a salt thereof (both reagents) were prepared. These were mixed at a ratio shown in Table 1 to prepare a light-burned magnesia powder composition. On the other hand, commercially available powdered lime nitrogen (CaCN ₂ 50 mass%, average particle diameter 0.1 mm) was prepared.

Cadmium sulfate was added to a commercially available horticultural soil to obtain artificially contaminated soil having a cadmium content of 0.5 ppm, 1 ppm or 5 ppm. After mixing the ratio shown in Table 1 with the light calcined magnesia powder composition and lime nitrogen to 100 parts by mass in terms of dry soil of this artificially contaminated soil, add water and mix with a pot mixer, and the maximum water capacity of the soil Of water. As a result, the agricultural material having the composition shown in Table 2 is mixed with the soil. This was put into a synthetic resin vat and air-dried, and passed through a crusher and a sieve to make a total of 7 mm. Transfer this soil to a planter, add water to make the maximum water content 60%, sow soy (variety: Tachinagaha) 12 seeds per planter, cultivate to 6 seeds after thinning, The actual cadmium content was measured by 1N hydrochloric acid extraction / atomic absorption spectrometry (Agriculture and Horticulture, Vol. 79, No. 8, Nakajima: Determination of cadmium in soybean grains by process quantitative analysis). The results are shown in Table 2.

As is clear from the comparison between the examples and the comparative examples, it can be seen that the agricultural material of the present invention is more excellent in the absorption suppression effect of cadmium. Moreover, from the comparison between Examples 1 and 2 and Examples 3 and 4, it can be seen that the effect of the present invention is promoted by further including an organic acid or a salt thereof.

The agricultural material of this invention can be used as a fertilizer, a soil improvement material, etc.

Claims (4)

It consists of a composition containing light-burned magnesia, phosphoric acid or a salt thereof, an organic acid or a salt thereof, and lime nitrogen, and their content is 60 to 90% by weight of light-burned magnesia, phosphoric acid or its 0.5 to 15 mass% salt as _P 2 _{O 5,} an organic acid or a salt (including 0%) 6 wt% or less, lime nitrogen is an agricultural material for 5 to 40 mass%, and its Applying the application amount to 100 parts by mass of soil (in terms of dry soil), lime nitrogen is 0.01 to 0.1 parts by mass as CaCN ₂ , and components other than lime nitrogen are 0.1 to 0.5 parts by mass. Agricultural material that suppresses cadmium absorption of crops without any characteristic and flooding after application. The agricultural material according to claim 1, wherein the lightly burned magnesia is a fired product of magnesium carbonate at 700 to 900 ° C. The agricultural material according to claim 1 or 2, wherein the phosphoric acid or a salt thereof is at least one selected from phosphoric acid, sodium phosphate and calcium phosphate. The agricultural material according to any one of claims 1 to 3 , wherein the organic acid or a salt thereof is at least one selected from lignin sulfonic acid, citric acid, gluconic acid, and sodium salts of these acids.