Liquid fertilizer and its application method

Abstract

To develop a liquid fertilizer containing high concentration nitrogen when being fertilized and causing no damage if attached to plants.SOLUTION: A liquid fertilizer contains 5-15% w / w of nitrogen when being fertilized and has a ratio of methylene urea and / or polymethylene urea relative to the total amount of nitrogen is 20% to 80%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a liquid fertilizer containing a high concentration of nitrogen and a method for applying the liquid fertilizer in a high-nitrogen-concentration state. [Background technology]

[0002] In recent years, in Japan, large-scale plots of farmland have been developed through field consolidation and consolidation with the aim of improving productivity. Typical land-use crops grown in large plots include soybeans and wheat, and it is known that the amount of nitrogen applied after the flowering stage of these crops has a significant effect on the subsequent yield and quality improvement (Non-Patent Documents 1 and 2). Therefore, top dressing during the flowering stage is an essential task for cultivation.

[0003] However, in recent years, the agricultural workforce in Japan has been aging, and top dressing work on large fields using conventional backpack sprayers or hand-pushed sprayers not only increases the amount of time spent working, but also places a significant workload on agricultural workers.

[0004] As a result, in recent years, with the aim of reducing the labor and costs involved in agricultural work, attention has been focused on the use of unmanned aerial vehicles, such as radio-controlled helicopters and agricultural drones, for fertilizing, spraying pesticides, and sowing seeds in large plots of farmland, and these have already been put to practical use in some areas.

[0005] When fertilization is performed using an unmanned aerial vehicle, the fertilizer is applied by aerial spraying from a high place. In this case, since the fertilizer is dispersed over a wide area due to the influence of wind, etc., it is desirable to spray it at a high concentration in order to achieve efficient fertilization. However, when a high concentration of fertilizer adheres to the leaves of crops, it causes leaf burn (so-called fertilizer burn) due to concentration disorders caused by fertilizer components, especially nitrogen, due to osmotic pressure (Non-Patent Document 3). Fertilizer burn causes a decrease in crop production, plant death, and a decrease in commercial value due to a decrease in aesthetic appearance.

[0006] Therefore, in the case of aerial spraying, liquid fertilizer is usually used that is diluted to a predetermined concentration so that the nitrogen during application does not cause fertilizer burn. However, due to dilution, the nitrogen concentration per spray area in one flight is inevitably low. Unmanned aerial vehicles cannot carry large amounts of liquid fertilizer. Therefore, in order to apply a certain amount of nitrogen that can achieve a topdressing effect, the same plot must be sprayed by flying multiple times. This makes it impossible to enjoy the original benefits of unmanned aerial vehicle spraying, such as labor saving and cost reduction. However, there is a trade-off between the amount of nitrogen applied in a single spray and the occurrence of fertilizer burn, and it has been extremely difficult to find a solution to this problem until now. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Masato Kuwahara, 1985, Agricultural Overview, Agricultural Technology Series, Crop Edition, Supplement No. 7: Techniques + 143-147. [Non-Patent Document 2] Yumi Shimazaki, 2015, Agricultural Overview, Agricultural Technology Series, Crop Edition, Supplementary No. 37 (4): Tech+174-74-174-82 [Non-Patent Document 3] John Sawyer, 2010, Nutrient Deficiencies and Application Injuries in Field Crops, Extension and Outreach publications, Iowa State University, IPM42. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to develop and provide a liquid fertilizer that has a high nitrogen content when applied and does not cause fertilizer burn even when attached to plants.

[0009] The present invention provides a method for applying liquid fertilizer containing a high concentration of nitrogen without causing fertilizer burn. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present inventors conducted various studies and found that a liquid fertilizer containing methyleneurea and / or polymethyleneurea at a specific ratio relative to the total nitrogen content does not cause fertilizer burn when sprayed aerially, even if the nitrogen content at the time of fertilization is 10 to 460 times that of conventional liquid fertilizers. The present invention is based on this novel finding and provides the following. (1) A liquid fertilizer having a nitrogen content of 5 to 15% w / w at the time of application and having a ratio of methyleneurea and / or polymethyleneurea to the total nitrogen content of 20% to 80%. (2) The liquid fertilizer according to (1), wherein the molecular weight of the polymethylene urea is 200 to 400. (3) A liquid fertilizer described in (1) or (2) for foliar spraying. (4) A nitrogen fertilization method comprising the steps of: The fertilization method includes a spraying step of spraying the liquid fertilizer according to any one of (1) to (3) onto the leaves of a target plant. (5) The fertilization method according to (4), wherein the foliar spraying is an aerial spraying from above the fertilized plant. (6) The fertilizer application method according to (4) or (5), wherein the foliar spraying is performed using a spraying device. (7) The fertilization method according to any one of (4) to (6), wherein a pesticide is simultaneously sprayed in the spraying step. Effect of the Invention

[0011] According to the liquid fertilizer of the present invention, even if it contains a high concentration of nitrogen at the time of application, it does not cause fertilizer burn on plants that have been fertilized by foliar spraying, etc. This makes it possible to supply nitrogen at a high concentration per application, thereby reducing the number of applications per unit area.

[0012] According to the nitrogen fertilization method of the present invention, liquid fertilizer can be sprayed with a high nitrogen content without causing fertilizer burn. [Brief description of the drawings]

[0013] [Figure 1-1] This is a diagram showing the state of fertilizer burn when liquid fertilizers No. 1 to 6 listed in Table 1 were sprayed on the leaves of soybeans. "Day 0" indicates the state of the leaves on the day of spraying, and "Day 8" indicates the state of the leaves 8 days after spraying. In the figure, the arrowheads indicate the whitened areas caused by fertilizer burn. [Figure 1-2] This is a diagram showing the effect of fertilizer burn when liquid fertilizers No. 7 to 11 listed in Table 1 were sprayed on soybeans. "Day 0" indicates the condition of the leaves on the day of spraying, and "Day 8" indicates the condition of the leaves 8 days after spraying. In the diagram, the arrowheads indicate white areas caused by fertilizer burn, and the white arrows indicate dead areas caused by fertilizer burn. [Diagram 2] This is a diagram showing the growth status of soybeans 8 days after foliar spraying of urea (left) and the liquid fertilizer of the present invention (right). The nitrogen content of the liquid fertilizers applied to the corresponding plants on the left and right is the same, and the nitrogen content is higher at the top of the photograph. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 1.Liquid fertilizer 1-1. Overview A first aspect of the present invention is a liquid fertilizer. The liquid fertilizer of the present invention is characterized in that the nitrogen content in the liquid fertilizer at the time of application and the component ratio of the nitrogen-containing substance in the total nitrogen amount of the liquid fertilizer are specified.

[0015] The liquid fertilizer of the present invention does not cause fertilizer burn when applied to leaves, despite its high nitrogen content. Therefore, it is possible to supply nitrogen at a high concentration per application, such as through aerial spraying. As a result, the amount of work and time required can be reduced, leading to labor savings and improved efficiency in agricultural work.

[0016] 1-2.Definition of Terms Terms used in this specification are defined below. In this specification, the term "fertilizer" refers to a nutrient source that contains all or part of the nutrients necessary for plant growth and is artificially supplied. The term "nutrient" refers to a substance whose deficiency causes some abnormality in the growth or reproduction of a plant, and whose recovery from the symptoms cannot be compensated for by the supply of other substances. Usually, it means an essential element for a plant. Typical plant nutrients include 17 essential elements, namely, hydrogen (H), oxygen (O), carbon (C), nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), sulfur (S), iron (Fe), manganese (Mg), zinc (Zn), boron (B), molybdenum (Mo), copper (Cu), chlorine (Cl), and nickel (Ni). In addition, compounds containing these elements (e.g., urea, ammonium salts, (per)phosphates) are also included in the term "nutrient" in this specification. Usually, a fertilizer contains multiple types of nutrients, but it may contain a single type of nutrient. When multiple types of fertilizers are contained, the combination and ratio are not particularly limited. However, the fertilizer in this specification includes a nitrogen source. The term "nitrogen source" refers to a compound containing nitrogen element, and a fertilizer component that serves as a nitrogen supply source.

[0017] In the present specification, the term "liquid fertilizer" (often abbreviated as "liquid fertilizer") refers to a fertilizer in liquid form. Its specific gravity may be in the range of 0.7 to 1.5, 0.75 to 1.45, 0.8 to 1.4, 0.85 to 1.35, or 0.9 to 1.3. Usually, it is an aqueous solution containing a fertilizer, particularly a nitrogen source in this specification. The viscosity of the liquid fertilizer is not particularly limited as long as it has a viscosity that allows it to be sprayed and has adhesion and spreadability to the stems and leaves of the plant to be fertilized, but it is usually in the range of 0.8 to 100 mPa·s, 1.0 to 80 mPa·s, 2.0 to 70 mPa·s, 3.0 to 60 mPa·s, 4.0 to 50 mPa·s, or 5.0 to 40 mPa·s at 20°C.

[0018] As used herein, the term "fertilization" refers to administering fertilizer or the like to a plant. Additionally, as used herein, the term "at the time of fertilization" refers to the time at which fertilization is performed.

[0019] In this specification, the term "plant to be fertilized" refers to a plant to be fertilized with the liquid fertilizer of the present invention. The type of plant is not limited. It may be either angiosperms or gymnosperms, and angiosperms include both dicotyledonous and monocotyledonous plants. Furthermore, it does not matter whether the plant is herbaceous or woody. Preferably, the plant is an agriculturally important crop plant or a horticulturally important horticultural plant. Examples of such plants include crop plants such as cereals, flowers, vegetables, and fruits. Specifically, among monocotyledonous plants, species belonging to the Poaceae family (e.g., rice, wheat, barley, rye, corn, sugarcane, foxtail millet, millet, barnyard millet, sorghum, sorghum, and turfgrass), species belonging to the Musaceae family (e.g., banana and musa), species belonging to the Liliaceae family (e.g., leek, onion, Chinese chive, tulip, hyacinth, muscari, and lily), species belonging to the Amaryllidaceae family (e.g., garlic), and species belonging to the Bromeliaceae family (e.g., pineapple) are relevant. In addition, among dicotyledonous plants, species belonging to the Fabaceae family (e.g., soybean, peanut, pea, kidney bean, adzuki bean, broad bean, sweet pea), species belonging to the Brassicaceae family (e.g., cabbage, radish, Chinese cabbage, rapeseed), species belonging to the Solanaceae family (e.g., tomato, eggplant, potato, tobacco, bell pepper, chili pepper, petunia), species belonging to the Cucurbitaceae family (e.g., pumpkin, watermelon, melon, cucumber), species belonging to the Convolvulaceae family (e.g., cucumber, convolvulaceae ... ceae (e.g., sweet potato), Rosaceae (e.g., strawberry, rose, apple, pear, peach, loquat, almond, plum, plum, cherry), Rutaceae (e.g., mandarin orange, orange, grapefruit, lemon, yuzu), Vitaceae (e.g., grape), Asteraceae (e.g., lettuce, chrysanthemum, dahlia, daisy, sunflower), Theaceae (e.g., sasanqua, tea plant).

[0020] In this specification, "leaf burn caused by concentration disorder" refers to the phenomenon in which, when a high concentration of fertilizer, in this specification especially a high concentration of nitrogen, adheres to the stems and leaves of a fertilized plant, the difference in osmotic pressure concentration causes water to flow out from the leaf surface to which the fertilizer adheres, resulting in the wilting or death of part or all of the leaf. This is also called "fertilizer burn," and this term is often used in this specification.

[0021] 1-3.Configuration The liquid fertilizer of the present invention is a liquid nitrogen fertilizer that contains a nitrogen source as a nutrient. In the liquid fertilizer of the present invention, the nitrogen content at the time of fertilization is 5 to 15% w / w, 6 to 15% w / w, 7 to 15% w / w, 8 to 15% w / w, 9 to 15% w / w, or 10 to 15% w / w based on the total weight. Since this is at the time of fertilization, the content may be higher than the above content at other times, for example, when commercially available or during storage. In this case, the fertilizer is diluted with water or the like so that the nitrogen content falls within the above range at the time of fertilization.

[0022] The liquid fertilizer of the present invention contains methylene urea and / or polymethylene urea as an essential nitrogen source, which is an active ingredient of the liquid fertilizer. Other nitrogen sources may include, but are not limited to, potassium nitrate, ammonium nitrate, ammonium sulfate, urea, monomethylol urea (NH2CONHCH2OH), biuret ((CONH2)2NH), and the like, as needed.

[0023] Methyleneurea (NH2CONHCH2NHCONH2) (MW: 132) is a slow-release nitrogen fertilizer, and polymethyleneurea (H[-NHCONHCH2] n NHCONH2) is a chain polymer. Both are also called ureaforms because they are synthesized by condensation of formaldehyde and urea. Depending on the degree of polymerization, they are classified as methylenediurea (M2U: equivalent to methyleneurea [C3H8N4O2]), dimethylenetriurea (2M3U: equivalent to polymethyleneurea [C5H 12 N6O3] (MW: 204), trimethylenetetraurea (3M4U: n=3 polymethyleneurea [C7H 16N8O4] (MW: 276), and tetramethylenepentaurea (4M5U: polymethyleneurea with n=4 [C9H 20 N 10 O5] (MW: 348) and the like are known. The degree of polymerization of the polymethylene urea in the liquid fertilizer of the present invention is not particularly limited, but a low degree of polymerization is preferable because a high degree of polymerization increases the viscosity and makes fertilization by spraying or the like difficult. For example, but not limited to, the degree of polymerization may be n=2 to 4 in the above chemical formula, that is, 2M3U (MW: 204), 3M4U (MW: 276), and 4M5U (MW: 348).

[0024] The molecular weight of the polymethyleneurea contained in the liquid fertilizer of the present invention is not constant because polymethyleneurea is not a single compound but a chain polymer compound with methyleneurea as a monomer. Therefore, the molecular weight of the polymethyleneurea is not limited. However, for the above-mentioned reasons, in the liquid fertilizer of the present invention, low-polymerization degree polymethyleneurea with n=2 to 4 is preferable, so that the molecular weight of the polymethyleneurea may be in the range of 200 to 400. When polymethyleneurea with various polymerization degrees is contained, the ratio of low-polymerization degree polymethyleneurea in the total polymethyleneurea may be increased so that a peak appears in the molecular weight range of 200 to 400.

[0025] In the present invention, liquid fertilizers with high nitrogen content are applied at a high nitrogen concentration. Contrary to conventional wisdom, even if applied in this state, the liquid fertilizer of the present invention does not cause fertilizer burn on the fertilized plant because it contains methylene urea and / or polymethylene urea at a predetermined ratio to the total nitrogen content. Therefore, the ratio of methylene urea and / or polymethylene urea to the total nitrogen content in the liquid fertilizer of the present invention is important for achieving the effects of the present invention. The value may be in the range of 20% to 80%, 30% to 75%, 40% to 70%, 50% to 65%, or 55% to 60%. In addition, the content ratio of methylene urea and polymethylene urea in the liquid fertilizer of the present invention is not particularly limited because there is no clear difference in the inhibitory effect against fertilizer burn. Similarly, the polymerization ratio of polymethylene urea in the liquid fertilizer of the present invention is not particularly limited because there is no clear difference in the inhibitory effect against fertilizer burn depending on the degree of polymerization for polymethylene urea. For the reasons mentioned above, it is preferable that the ratio of the low polymerization degree polymethyleneurea (n=2 to 4) is high.

[0026] The liquid fertilizer of the present invention can contain other nutrients in addition to the nitrogen source. The other nutrients are not particularly limited. For example, in addition to hydrogen, oxygen, and carbon, the liquid fertilizer can contain the above-mentioned potassium, phosphorus, magnesium, calcium, sulfur, iron, manganese, zinc, boron, molybdenum, copper, chlorine, and nickel.

[0027] The liquid fertilizer of the present invention may further contain, in addition to an agriculturally acceptable solvent, an agriculturally acceptable component having another action, if necessary.

[0028] The term "agriculturally acceptable solvent" refers to a solvent that, when applied to a plant, has no or very little harmful effect on the plant body and / or the environment such as soil and water quality. Although not limited thereto, the solvent in the liquid fertilizer of the present invention is preferably water (including pure water, distilled water, and aqueous solutions).

[0029] Furthermore, the agriculturally acceptable components having other actions include, for example, agricultural chemicals such as insecticides or fungicides, or growth enhancers used in agriculture.

[0030] The method of application of the liquid fertilizer of the present invention is not particularly limited. For example, application by addition to soil or water such as paddy field for the purpose of absorption from the roots is also possible. However, since the liquid fertilizer of the present invention is in a liquid form, it can be applied by spraying (including spraying), coating, or immersion to the stems and leaves. In particular, in view of the fact that the nitrogen source, which is the active ingredient of the liquid fertilizer of the present invention, can be absorbed from the stems and leaves, and the purpose of the present invention, it is preferable to use it for spraying purposes. For example, it can be used for foliar spraying, in which the liquid fertilizer is sprayed from above the target plant using an aircraft (including agricultural drones, radio-controlled helicopters, etc.), a sprinkler, or a large work machine (including boom sprayers, power sprayers, etc.), and the liquid fertilizer is directly sprayed on the stems and leaves of the target plant.

[0031] 2. Nitrogen fertilization method 2-1. Overview The second aspect of the present invention is a method for applying nitrogen. In the method of the present invention, the liquid fertilizer described in the first aspect is applied in a high-concentration nitrogen state. According to the fertilization method of the present invention, even if high-concentration nitrogen is directly applied to the plant body, particularly the stem and leaf parts, fertilizer burn does not occur. Therefore, a high-concentration nitrogen-containing liquid fertilizer can be applied in one application. This enables efficient nitrogen topdressing by unmanned aerial vehicles, which can lead to labor saving and cost reduction in the application of nitrogen to vast farmland. In addition, it can be easily mixed with pesticides, making it possible to simultaneously control pests and topdressing, which can contribute to improving the productivity of agricultural crops.

[0032] 2-2. Method 2-2-1. Spraying process The nitrogen fertilization method of the present invention includes a spraying step as an essential step. The "spraying step" is a step of spraying the liquid fertilizer described in the first embodiment on the leaves of a fertilized plant. This step makes it possible to utilize the advantages of the liquid fertilizer described in the first embodiment and to solve the problems of the conventional fertilization method using unmanned aerial vehicles or the like for vast farmland, which aims to reduce labor and costs in farming.

[0033] "Foliar application" is a fertilization method in which liquid fertilizer is applied to the leaves of a target plant. The liquid fertilizer applied to the leaves is absorbed through the leaves and used by the plant. In the present invention, the nitrogen source, which is the main active ingredient in the liquid fertilizer, is the subject of particular application.

[0034] The method of foliar spraying may be any method known in the art, as long as it allows the liquid fertilizer to be sprayed so as to come into direct contact with the leaf surface, and is not particularly limited. For example, the liquid fertilizer may be sprayed directly onto the leaf surface of the target plant manually using a sprayer or the like, or the liquid fertilizer may be applied to the leaf surface with a brush, etc. However, in view of the problem to be solved by the present invention, a method of spraying the liquid fertilizer from the air from above the target plant is usually preferred.

[0035] The method of aerial spraying of liquid fertilizer may be any method known in the art, and is not limited thereto. For example, the liquid fertilizer may be sprayed using a spraying device. Specific examples of the spraying device include boom sprayers or power sprayers capable of automatically spraying liquid fertilizer, unmanned aerial vehicles such as agricultural drones and radio-controlled helicopters, etc.

[0036] The feature of this process is that the nitrogen content in the liquid fertilizer at the time of fertilization, i.e., at the time of spraying, is 5 to 15% w / w based on the total weight of the liquid fertilizer. In general, in order to avoid fertilizer burn when spraying aerially, the liquid fertilizer is diluted before use so that the nitrogen content is usually in the range of 0.03 to 0.1% w / w. Therefore, the liquid fertilizer of the present invention is applied at a nitrogen concentration about 50 to 460 times higher than that of conventional liquid fertilizers.

[0037] In the present invention, the liquid fertilizer according to the first aspect can be absorbed not only by leaves but also by the whole plant, including the roots. Therefore, it can be sprayed or added to the soil or paddy field in which the plant to be fertilized is grown.

[0038] 2-2-2.Amount of fertilizer applied The amount of liquid fertilizer to be applied in the nitrogen fertilization method of the present invention is not particularly limited. An appropriate amount of fertilizer may be calculated based on the type of plant to be fertilized, the purpose of fertilization, and / or the amount of nitrogen required per unit area of ​​the farmland.

[0039] The nitrogen content contained in the liquid fertilizer according to the first embodiment at the time of fertilization is about 50 to 460 times the nitrogen content at the time of fertilization of the conventional liquid fertilizer for foliar application, as described above. Even if a liquid fertilizer having an extremely high concentration of nitrogen content, which is completely different from the common sense of such liquid fertilizers for foliar application, is applied, the nitrogen fertilization method of the present invention can avoid the problem of fertilizer burn. Since the amount of nitrogen fertilizer applied per one application can be increased, the number of fertilizations can be reduced, thereby saving labor and reducing costs in agricultural work. In addition, the nitrogen content per application can be increased compared to the conventional fertilization method. As a result, the same or more amount of fertilizer can be applied with less labor, and the yield per unit area of ​​agricultural crops can also be increased.

[0040] 2-2-3.Applicable Location The location to which the nitrogen fertilization method of the present invention is applied is not particularly limited. It may be applied to any location where foliar application is possible and fertilization such as top dressing is required. Application to large plots of land, paddy fields, orchards, gardens, golf courses, and other large farmland is particularly preferred because it allows the advantages of the method of the present invention to be utilized. Below, suitable examples of application locations and their advantages are described.

[0041] (1) Application in large plots of land For land-use crops (wheat, soybeans), the protein content of the harvested seeds increases when nitrogen is applied as a top dressing during the flowering and thickening stages. By using the nitrogen fertilization method of the present invention, it is possible to apply a sufficient amount of nitrogen with less work, even in large fields, compared to conventional methods, and the amount of application can also be reduced. As a result, it becomes possible to harvest high-grade wheat and barley, and to improve the saleable yield. Furthermore, it is also possible to simplify work by applying it simultaneously with pesticides.

[0042] (2) Application in orchards In orchards, the more sunlight there is, the higher the yield and the higher the quality of the fruit that can be harvested, with a high sugar content. For example, citrus orchards are often located on southern slopes where sunlight conditions are good. Since the workload on such steep slopes is extremely high, the application of this method of aerial spraying using unmanned aerial vehicles is extremely suitable in terms of labor saving and reducing the labor required.

[0043] (3) Application in tea fields In tea cultivation, fertilization with spring fertilizer (sprout fertilizer) is required to improve the quality and yield of the first harvest. In addition, as a measure against poor growth due to bad weather, the quality can be improved by increasing the nitrogen content through appropriate fertilization. On the other hand, since tea is generally cultivated in vast hilly areas, the application of this method of aerial spraying using boom sprayers, sprinklers, etc. is extremely suitable in terms of saving labor and reducing the workload of agricultural work. In addition, in tea cultivation, the fertilization period and the pest control period overlap, increasing the workload, but by applying the method of the present invention, it is possible to spray pesticides at the same time, which can simplify the work and reduce the labor.

[0044] (4) Application in rice paddies When applying top dressing to prevent nutrient loss due to high temperatures in rice cultivation, the application of this method of aerial spraying using unmanned aerial vehicles or other devices in the vast wetlands of rice paddies is extremely advantageous in terms of reducing labor and effort.

[0045] (5) Application to golf courses and parks Grass laid on golf courses, parks, etc. requires fertilization in the spring to promote growth and in the fall to strengthen cold resistance before winter. Since fertilization in vast areas dotted with trees and hilly areas is left as is in order to preserve the natural scenery and no farmland is developed, the application of this method of aerial spraying using unmanned aerial vehicles is extremely suitable in terms of labor saving and lightening the workload.

[0046] 2-3.Effects Liquid fertilizer can be applied without burning the fertilizer due to its high nitrogen content, which reduces the number of fertilizer applications per unit area. In addition, it enables efficient nitrogen topdressing using unmanned aerial vehicles, which reduces the labor required for nitrogen fertilization on large farmland and may also lead to cost reductions. EXAMPLES

[0047] <Experimental Example 1: Analysis of the components of the base solution> (the purpose) The components of the basal liquid fertilizer used in the liquid fertilizer according to the first aspect of the present invention are analyzed. (method) To prepare the liquid fertilizer of the present invention, a stock solution of a commercially available nitrogen liquid fertilizer CoRoN (registered trademark) (Helena Agri Enterprises LLC), which contains methyleneurea and polymethyleneurea as its main components, was used as the basal liquid fertilizer. CoRoN is a liquid nitrogen fertilizer with a specific gravity of about 1.28, pH 10, and viscosity of 38 mPa·s, and is mainly used for foliar spraying. The nitrogen content by form in this CoRoN stock solution and the content ratio of each form in the total nitrogen amount were analyzed by the following method. Determination of total nitrogen: Quantification was performed using the sulfuric acid method. - Urea nitrogen determination: CoRoN was fractionated by HPLC using 85% (v / v) acetonitrile solvent, and ammonia nitrogen was detected and determined using a UV detector at a detection wavelength of 195 nm. Note that urea in the presence of methyleneurea and polymethyleneurea, such as CoRoN, cannot be determined by the ammonia nitrogen detection method due to urease activity inhibition, so the amount was determined using this method. -Quantification of ammonia nitrogen: CoRoN was analyzed and quantified by the indophenol method. - Determination of nitrate nitrogen: Using a nitrate ion meter (HORIBA: B743), CoRoN was analyzed in the measurement range of 62 to 6200 ppm (mg / L) to determine the amount of nitrate nitrogen. Quantitative determination of methyleneurea / polymethyleneurea nitrogen: The amount of methyleneurea / polymethyleneurea nitrogen was calculated by subtracting the sum of urea nitrogen, ammonia nitrogen, and nitrate nitrogen from the total nitrogen amount.

[0048] (result) The CoRoN stock solution contains the various forms of nitrogen shown in Table 1 below.

[0049] [Table 1]

[0050] The nitrogen content per total weight of the CoRoN solution was about 28% w / w, and it was found that about 75% of the total nitrogen was methyleneurea / polymethyleneurea nitrogen.

[0051] CoRoN is sold in a concentrated state, and the instructions state that it should be diluted with water to a specified ratio when used for fertilization. The recommended dilution ratio is 50 times in the United States and 100 to 800 times in Japan. Therefore, the nitrogen content of the diluted liquid fertilizer at the time of application should be in the range of 0.035 to 0.56% w / w.

[0052] <Experimental Example 2: Preparation of liquid fertilizer containing high concentration of nitrogen> (the purpose) A liquid fertilizer of the present invention for use in Examples 1 and 2 is prepared. (method) As shown in Table 1, the nitrogen content in the CoRoN stock solution is about 28% w / w, and the ratio of methyleneurea and / or polymethyleneurea to the total nitrogen amount is about 75%. Here, in order to verify the ratio of methyleneurea and / or polymethyleneurea to the total nitrogen amount and the fertilizer burn suppression effect, solutions with various ratios were prepared. Specifically, the CoRoN stock solution was mixed with an appropriate amount of urea to maintain the nitrogen content of 28% w / w, and the ratio of methyleneurea and / or polymethyleneurea to the total nitrogen amount was prepared to be about 20%, about 10%, and about 5%. Furthermore, the stock solution and each were diluted 2-fold and 5-fold with water to adjust the nitrogen content to 14% w / w and 5.6% w / w. In addition, a liquid fertilizer containing urea as a nitrogen source was also prepared as a positive control. For the negative control, water used as a solvent was used.

[0053] (result) The specific dilution ratio, the nitrogen content (%w / w) in the diluted solution, and the ratio of methyleneurea (MU) and / or polymethyleneurea (PMU) in the total nitrogen (TN) are shown in Table 2. [Table 2]

[0054] <Example 1: Foliar spray test of each liquid fertilizer on soybeans> (the purpose) The effects of fertilizer burn caused by foliar spraying of each liquid fertilizer prepared in Experimental Example 2 will be verified using soybeans. (method) Each liquid fertilizer (Table 2: No. 1-11) prepared in Experimental Example 2 was sprayed once (approximately 0.8 g) on ​​one leaf (pinnate compound leaf consisting of three leaflets) of soybean (variety: Fukuyutaka) three months after sowing. The amount of solution sprayed was set to a level that would drip with a large amount of spray, assuming drift, and no spreading agent was used. The state of fertilizer burn on the leaves sprayed on the leaves 0 days and 8 days after application was evaluated on a 5-point scale based on the state of leaf chlorosis using the following criteria. · -: Normal ±: Slight browning +: Some browning ++: Browning +++: Significant browning (result) The results are shown in Table 3 and Figure 1 (1-1 to 1-2).

[0055] [Table 3]

[0056] In the table, each number corresponds to the liquid fertilizer number shown in Table 2. The nitrogen content in liquid fertilizers used to avoid fertilizer burn during aerial spraying is usually in the range of 0.03 to 0.1% w / w. In addition, since the nitrogen content in liquid fertilizers after dilution at the recommended dilution ratio of CoRoN is 0.035 to 0.56% w / w, liquid fertilizers No. 1 to 8 have extremely high nitrogen concentrations of 10 to 460 times that amount. When liquid fertilizers with such high nitrogen concentrations are sprayed on leaves, symptoms of fertilizer burn usually appear 8 days after spraying, as in the positive control Nos. 9 and 10. This fertilizer burn does not recover thereafter, but progresses to severe symptoms such as browning of leaves or death.

[0057] However, when the ratio of methyleneurea and polymethyleneurea to the total nitrogen amount was 20% or more, no fertilizer burn occurred due to foliar application even 8 days after application, as shown in Nos. 1 to 4. Moreover, as shown in Nos. 1 and 2, even when the ratio of methyleneurea and polymethyleneurea was as high as 75%, the fertilizer burn suppression effect was maintained, and no other problems occurred.

[0058] The above results show that even if the liquid fertilizer has a very high nitrogen content of approximately 5 to 15% w / w, fertilizer burn will not occur as long as the ratio of methyleneurea and polymethyleneurea is 20 to 80% of the total nitrogen content in the liquid fertilizer.

[0059] In addition, Fig. 2 shows the growth status of soybeans 8 days after foliar spraying of urea and the liquid fertilizer of the present invention. Although the nitrogen content of both is the same on the left and right, the liquid fertilizer of the present invention containing methyleneurea and polymethyleneurea not only does not cause fertilizer burn, but also promotes vigorous growth.

[0060] <Example 2: Foliar spray test of each liquid fertilizer on wheat> (the purpose) The effect of fertilizer burn caused by foliar spraying is examined in the same manner as in Example 1 using wheat, a monocotyledonous plant. (method) Of the liquid fertilizers prepared in Experimental Example 2, those containing a high nitrogen content of 14% w / w (Table 2: No. 1, 3, 5, 7) were sprayed twice (approximately 0.8 g / time) onto the leaves of potted wheat (variety: Seto Kirara) plants two weeks after sowing. The state of fertilizer burn on the leaves was evaluated 0 days and 9 days after application. The criteria for fertilizer burn were the same as in Example 1. (result) The results are shown in Table 4.

[0061] [Table 4]

[0062] It was shown that fertilizer burn can be suppressed in monocotyledonous wheat by setting the MU / PMU ratio to 20% or more, even though the monocotyledonous wheat has a very high nitrogen content of 14% w / w, just like soybeans. Therefore, it was demonstrated that the liquid fertilizer of the present invention is effective not only for dicotyledonous plants, but also for monocotyledonous plants, and can be widely applied to plants.

Claims

1. A method for suppressing leaf burn caused by application of liquid nitrogen fertilizer consisting of a highly concentrated nitrogen source, comprising: a spraying step of spraying the liquid nitrogen fertilizer on the leaves of a plant to be fertilized. Including, The liquid nitrogen fertilizer has a nitrogen content of 5 to 15% w / w when applied, and the ratio of methylene urea and / or polymethylene urea to the total nitrogen content is 20% to 80%. The suppression method.

2. 2. The method of claim 1, wherein the molecular weight of the polymethylene urea is 200-400.

3. 3. The method according to claim 1 or 2, wherein the foliar spray is an aerial spray from above the target plant.

4. The method of any one of claims 1 to 3, wherein the foliar application is performed using a spraying device.

5. The method according to any one of claims 1 to 4, wherein a pesticide is simultaneously sprayed in the spraying step.

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