阅读说明：本技术 用于防治北方落叶果树生理性病害的聚天冬氨酸液体水溶肥及其制备方法 (Polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees and preparation method thereof ) 是由 焦永康 于雪松 吴学强 赵龙梅 李文曦 范占权 于 2021-10-14 设计创作，主要内容包括：本发明公开了一种用于防治北方落叶果树生理性病害的聚天冬氨酸液体水溶肥,包括由聚琥珀酰亚胺在45～75℃、内肽酶催化作用下水解得到的重均分子量为1000～2000D且该区间分布率不低于90％的聚天冬氨酸。本发明通过对水解条件进行合理控制,获得能够稳定且有效促进营养元素在落叶果树生长过程吸收的聚天冬氨酸,以此作为水溶肥的主剂或增效助剂,从而得到对落叶果树生理性病害具有显著防治作用的聚天冬氨酸液体水溶肥。(The invention discloses a polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees, which comprises polyaspartic acid, wherein the polyaspartic acid is obtained by hydrolyzing polysuccinimide at 45-75 ℃ under the catalysis of endopeptidase, has the weight-average molecular weight of 1000-2000D, and the distribution rate of the polyaspartic acid in the interval is not lower than 90%. According to the invention, by reasonably controlling hydrolysis conditions, polyaspartic acid capable of stably and effectively promoting nutrient elements to be absorbed in the growth process of deciduous fruit trees is obtained and is used as a main agent or a synergistic auxiliary agent of the water-soluble fertilizer, so that the polyaspartic acid liquid water-soluble fertilizer with a remarkable effect of preventing and treating physiological diseases of deciduous fruit trees is obtained.)

1. The polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees is characterized by comprising the following components:

polyaspartic acid with the weight-average molecular weight of 1000-2000D and the interval distribution rate of not less than 90% is obtained by hydrolyzing polysuccinimide under the catalysis of endopeptidase at 45-75 ℃.

2. The liquid water-soluble polyaspartic acid fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees according to claim 1, wherein the polyaspartic acid is prepared by the following method:

the method comprises the steps of taking polysuccinimide as a main raw material, adding water, fully and uniformly stirring to form paste, adding a pre-activated endopeptidase catalyst, carrying out hydrolysis reaction at the temperature of 45-75 ℃, adding an alkaline substance to quickly terminate the reaction when the weight average molecular weight of a hydrolysate reaches a required range, and obtaining the polyaspartic acid.

3. The polyaspartic acid liquid water-soluble fertilizer for controlling physiological diseases of northern deciduous fruit trees according to claim 1, which is characterized in that: the polysuccinimide is prepared by a thermal polymerization method.

4. The polyaspartic acid liquid water-soluble fertilizer for controlling physiological diseases of northern deciduous fruit trees according to claim 1, which is characterized in that: the endopeptidase is serine protease or/and aspartic protease.

5. The polyaspartic acid liquid water-soluble fertilizer for controlling physiological diseases of northern deciduous fruit trees according to claim 2, which is characterized in that: the alkaline substance is selected from one or more of oxides, hydroxides and carbonates containing potassium, ammonium, calcium, zinc, manganese, magnesium and iron.

6. The polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees according to any one of claims 1 to 5, which is characterized by comprising the following components in parts by mass: 1-50 parts of polyaspartic acid, 0-50 parts of nutrient substances and 100 parts of water;

the nutrient substances comprise 0-30 parts of nitrogen-containing nutrient substances, 0-30 parts of phosphorus-containing nutrient substances, 0-30 parts of potassium-containing nutrient substances and 0-30 parts of beneficial medium and trace element-containing substances, and the total amount of all nutrient substance components is not more than 50 parts.

7. The polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees according to any one of claims 1 to 5, wherein polyaspartic acid is added to the water-soluble fertilizer to obtain the polyaspartic acid liquid water-soluble fertilizer, and the addition amount of polyaspartic acid in 100 parts by mass of the polyaspartic acid liquid water-soluble fertilizer is 1 to 50 parts.

8. The polyaspartic acid liquid water-soluble fertilizer for controlling physiological diseases of northern deciduous fruit trees according to claim 1, which is characterized in that: the northern deciduous fruit tree physiological diseases comprise apple water core disease and yellow comb pear chicken foot disease.

9. A preparation method of the polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees according to any one of claims 1 to 8, which is characterized by comprising the following preparation steps:

a. obtaining polysuccinimide: selecting polysuccinimide prepared by a thermal polymerization method, wherein the content of free aspartic acid in the polysuccinimide is required to be less than or equal to 2.0 percent;

b. preparation of polyaspartic acid: taking polysuccinimide as a main raw material, adding water, fully and uniformly stirring to form paste, adding a catalyst endopeptidase which is activated in a water bath at 30 ℃ for 3-4 h in advance, uniformly adding and fully mixing the catalyst, heating to 45-75 ℃ after the catalyst is fully added to perform hydrolysis reaction, adding an alkaline substance to quickly stop the reaction and adjusting the pH value of the material after 12-48 hours, thus obtaining polyaspartic acid with the weight average molecular weight of 1000-2000D and the interval distribution rate of not less than 90%;

c. preparing a water-soluble fertilizer: and c, uniformly mixing the polyaspartic acid prepared in the step b with other components of the water-soluble fertilizer, or adding the polyaspartic acid prepared in the step b into the liquid water-soluble fertilizer and uniformly stirring to obtain the polyaspartic acid liquid water-soluble fertilizer.

10. The preparation method of the polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees according to claim 9, which is characterized by comprising the following steps: in the step b, the adding amount of water accounts for 40-60% of the total mass of the reaction system, the adding amount of the catalyst accounts for 0.5-1.5% of the total mass of the reaction system, and the adding amount of the alkaline substance accounts for 10-20% of the total mass of the reaction system.

Technical Field

The invention relates to the technical field of water soluble fertilizers, in particular to a polyaspartic acid liquid water soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees and a preparation method of the water soluble fertilizer.

Background

The water-soluble fertilizer is a compound fertilizer which can be completely dissolved in water and contains nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium, trace elements, amino acid, humic acid, alginic acid and the like, and is divided into a macroelement water-soluble fertilizer, a medium-element water-soluble fertilizer, a trace element water-soluble fertilizer, an amino acid-containing water-soluble fertilizer, a humic acid-containing water-soluble fertilizer, an organic water-soluble fertilizer and the like according to the nutrient content. The water soluble fertilizer is used as an important component of agricultural fertilizer, is mainly used for foliage spraying, spraying (dripping) irrigation, flushing application and the like, and can supplement nutrient elements which are needed urgently in the critical period of crop growth. With the promotion of national water-saving engineering and the development of water and fertilizer integration technology, the production scale of domestic water-soluble fertilizer is changed newly every year, statistics shows that the production scale of the domestic water-soluble fertilizer is only 30 ten thousand tons in 2009, and is close to 370 ten thousand tons in 2015, and then the domestic water-soluble fertilizer is popularized and applied on a large scale. In addition to the scale enlargement, the water-soluble fertilizer in China also gradually develops from a single mineral nutrient water-soluble fertilizer to diversification, specialization and synergism.

Polyaspartic acid, a world-recognized green chemical, has been widely applied in the aspect of agricultural fertilizer synergism, but has not been reported in detail in the aspect of direct application to fruit tree physiological diseases. The molecular weight distribution of the existing polyaspartic acid on the market is scattered, the absorption rate and the effect are different, which is contrary to the characteristics of quick absorption and high utilization rate of water-soluble fertilizers, so that the polyaspartic acid with obvious synergy in the conventional fertilizers (urea, compound fertilizers and the like) is limited to be applied to the water-soluble fertilizers.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides the polyaspartic acid liquid water-soluble fertilizer for preventing and treating the physiological diseases of the northern deciduous fruit trees, which is characterized in that polyaspartic acid with a specific molecular weight range, which is obtained by hydrolyzing specific raw materials under specific conditions, is used as a main agent or a synergistic auxiliary agent of the water-soluble fertilizer, so that the water-soluble fertilizer can stably and efficiently play a role in preventing and treating the physiological diseases of the northern deciduous fruit trees.

In order to achieve the purpose, the polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees, provided by the invention, comprises the following components:

polyaspartic acid with the weight-average molecular weight of 1000-2000D and the interval distribution rate of not less than 90% is obtained by hydrolyzing polysuccinimide under the catalysis of endopeptidase at 45-75 ℃.

As a limitation to the above technical solution, the polyaspartic acid is prepared by the following method:

the method comprises the steps of taking polysuccinimide as a main raw material, adding water, fully and uniformly stirring to form paste, adding a pre-activated endopeptidase catalyst, carrying out hydrolysis reaction at the temperature of 45-75 ℃, adding an alkaline substance to quickly terminate the reaction when the weight average molecular weight of a hydrolysate reaches a required range, and obtaining the polyaspartic acid.

The polyaspartic acid liquid water-soluble fertilizer disclosed by the invention is prepared by utilizing polysuccinimide under a specific enzyme hydrolysis condition, has the characteristics of small weight average molecular weight, concentrated molecular weight, high water solubility and high absorption rate, can exert the advantages of activating soil nutrition, improving the fertilizer utilization rate, increasing yield and improving quality, and the like, is stable and effective in promoting the absorption of nutrient elements in the growth process of deciduous fruit trees, effectively improves the stress resistance of crops, so that the stress resistance of the crops is obviously improved, and the application effect of the water-soluble fertilizer in the aspect of physiological disease control of the deciduous fruit trees is comprehensively improved. The polyaspartic acid obtained by the scheme of the invention can be used as a main agent of the water-soluble fertilizer and also can be used as a synergist to be added into the existing water-soluble fertilizer, so that the physiological disease control effect of the water-soluble fertilizer on deciduous fruit trees can be obviously improved, and the green and efficient water-soluble fertilizer is formed.

As a limitation to the technical scheme, the polysuccinimide is prepared by a thermal polymerization method.

As a limitation to the above technical scheme, the endopeptidase is selected from serine protease or/and aspartic protease.

As the limitation of the technical scheme, the alkaline substance is selected from one or more of oxides, hydroxides and carbonates containing potassium, ammonium, calcium, zinc, manganese, magnesium and iron.

Further limiting the hydrolysis condition of the polyaspartic acid to ensure the stability and the high efficiency of the polyaspartic acid as a raw material of the water-soluble fertilizer, thereby ensuring the prevention and treatment effect of the water-soluble fertilizer.

As the limitation to the technical scheme, the polyaspartic acid liquid water-soluble fertilizer comprises the following components in parts by mass: 1-50 parts of polyaspartic acid, 0-50 parts of nutrient substances and 100 parts of water;

the nutrient substances comprise 0-30 parts of nitrogen-containing nutrient substances, 0-30 parts of phosphorus-containing nutrient substances, 0-30 parts of potassium-containing nutrient substances and 0-30 parts of beneficial medium and trace element-containing substances, and the total amount of all nutrient substance components is not more than 50 parts.

Wherein the nitrogen-containing nutrient substances comprise one or more of urea, urea phosphate, ammonium carbonate, ammonium nitrate, ammonium sulfate, ammonium chloride and ammonia water; the phosphorus-containing nutrient comprises one or more of urea phosphate, ammonium phosphate, potassium phosphate and phosphoric acid; the potassium-containing nutrient substance comprises one or more of potassium phosphate, potassium nitrate, potassium chloride, potassium sulfate, potassium carbonate and potassium hydroxide; the beneficial trace element-containing substances include one or more of water-soluble inorganic salts containing zinc, boron, iron, manganese, calcium, magnesium and the like and can be applied to agriculture.

As a limitation on the technical scheme, polyaspartic acid is added into the existing water-soluble fertilizer to obtain a polyaspartic acid liquid water-soluble fertilizer, and the adding amount of polyaspartic acid in 100 parts by mass of the polyaspartic acid liquid water-soluble fertilizer is 1-50 parts.

As a limitation on the technical scheme, the physiological diseases of northern deciduous fruit trees comprise apple water core disease and yellow comb pear chicken foot disease.

Further limiting the formula of the polyaspartic acid liquid water-soluble fertilizer, the addition amount of polyaspartic acid into the water-soluble fertilizer and the specific physiological diseases of deciduous fruit trees, and providing comprehensive, stable and effective technical guidance for the disease prevention and control application of the polyaspartic acid liquid water-soluble fertilizer.

Meanwhile, the invention also provides a preparation method of the polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees, which comprises the following preparation steps:

a. obtaining polysuccinimide: polysuccinimide prepared by a thermal polymerization method is selected, wherein the content of free aspartic acid is less than or equal to 2.0 percent;

b. preparation of polyaspartic acid: taking polysuccinimide as a main raw material, adding water, fully and uniformly stirring to form paste, adding a catalyst endopeptidase which is activated in a water bath at 30 ℃ for 3-4 h in advance, uniformly adding and fully mixing the catalyst, heating to 45-75 ℃ after the catalyst is fully added to perform hydrolysis reaction, adding an alkaline substance after 12-48 hours to rapidly terminate the reaction and simultaneously adjust the pH value of the material, thereby obtaining polyaspartic acid with the weight-average molecular weight of 1000-2000D and the interval distribution rate of not less than 90%; wherein the content of polyaspartic acid is more than or equal to 25% (w/w), the content of nutrient elements in polyaspartic acid is 2.4-6.4% (w/w), and the solid content is 30-50% (w/w);

c. preparing a water-soluble fertilizer: and c, uniformly mixing the polyaspartic acid prepared in the step b with other components of the water-soluble fertilizer, or adding the polyaspartic acid prepared in the step b into the existing liquid water-soluble fertilizer and uniformly stirring to obtain the polyaspartic acid liquid water-soluble fertilizer.

As a limitation to the technical scheme, in the step b, the adding amount of water accounts for 40-60% of the total mass of the reaction system, the adding amount of the catalyst accounts for 0.5-1.5% of the total mass of the reaction system, and the adding amount of the alkaline substance accounts for 10-20% of the total mass of the reaction system.

The key point of the polyaspartic acid liquid water-soluble fertilizer is the hydrolysis preparation of polyaspartic acid. The source of raw material polysuccinimide is limited, and the advantageous performance of the product after hydrolysis is ensured; endopeptidase is used as a hydrolysis catalyst, hydrolysis is carried out under the condition of medium and low temperature, and alkaline substances are added to stop the reaction, so that the control of the molecular weight range and concentration of a hydrolysate is realized, the control effect of the water-soluble fertilizer on the physiological diseases of deciduous fruit trees is ensured, the safety and efficiency of the production process can be improved, and the safety of crop growth is further facilitated.

In conclusion, the polyaspartic acid liquid water-soluble fertilizer disclosed by the invention has the advantages that the specific polyaspartic acid is added into the existing water-soluble fertilizer as a water-soluble fertilizer main agent or a synergistic auxiliary agent, so that the absorption of nutrient elements in the growth process of deciduous fruit trees can be stably and effectively promoted, and the application effect of preventing and treating physiological diseases of deciduous fruit trees is improved. The preparation of the liquid water-soluble fertilizer containing polyaspartic acid takes the hydrolysis of polyaspartic acid as a technical key, and obtains the green and efficient water-soluble fertilizer by effectively controlling the hydrolysis conditions.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Examples

The embodiment relates to a polyaspartic acid liquid water-soluble fertilizer for preventing and treating physiological diseases of northern deciduous fruit trees and preparation thereof.

Raw materials are selected, polysuccinimide is an industrial product produced by a thermal polymerization method, and the content of free aspartic acid is not more than 0.2%; the aspartic protease selects industrial products with 5W enzyme activity; other raw materials are all industrial grade products.

Example 1

A water-soluble fertilizer for preventing and treating apple water core diseases comprises 20kg of calcium-containing polyaspartic acid, 30kg of potassium-containing polyaspartic acid, 5kg of potassium sulfate, 10kg of monopotassium phosphate, 3kg of phosphoric acid and 32kg of water, wherein the total amount is 100 kg.

Wherein the calcium-containing polyaspartic acid and the potassium-containing polyaspartic acid are prepared by the following method:

5.5kg of water and 3.0kg of polysuccinimide were added to the reactor in one portion, and the stirring was started. Adding aspartic protease which is activated in water bath at 30 ℃ for 4 hours in advance after the aspartic protease is uniform, controlling the adding time to be 30 +/-5 min and the adding amount to be 50g in the enzyme adding process, raising the temperature of the reactor after the catalyst is completely added to control the reaction temperature to be 45 +/-5 ℃, starting timing and preserving the temperature for 36 hours after the set temperature is reached. And (3) monitoring the molecular weight at any time by Gel Permeation Chromatography (GPC) when the heat preservation period is about to end, quickly and uniformly adding 1.1kg of calcium hydroxide (or 0.9kg of potassium hydroxide) to terminate the reaction when the required molecular weight range is reached, generally controlling the alkali adding time according to the temperature of a material system, controlling the temperature of the material system to be less than or equal to 100 ℃, and approaching the critical temperature of 100 ℃ as much as possible, and simultaneously avoiding the influence on the efficacy of the polyaspartic acid due to low hydrolysis molecular weight caused by slow alkali addition caused by temperature control. Adding alkaline substances and adjusting the pH of the materials to prepare calcium-containing polyaspartic acid (or potassium-containing polyaspartic acid), and carrying out sample sending detection when the temperature of the materials is reduced to be lower than 40 ℃, wherein the detection result shows that the content of the polyaspartic acid is more than or equal to 25 percent, the content of the aspartic acid is less than or equal to 4.0 percent, the weight average molecular weight is 1500D, the distribution rate of the interval is not less than 90 percent, the pH value is 6.2, and the content of calcium is more than or equal to 5.0 percent or the content of potassium is more than or equal to 6.0 percent.

Mixing the prepared calcium-containing polyaspartic acid, potassium-containing polyaspartic acid and other components uniformly according to the following operations: adding 32kg of water into a container at one time, adding 30kg of potassium-containing polyaspartic acid, uniformly stirring, continuously adding 5kg of potassium sulfate, 10kg of monopotassium phosphate and 3kg of phosphoric acid until the potassium sulfate, the monopotassium phosphate and the phosphoric acid are dissolved, finally slowly adding 20kg of calcium-containing polyaspartic acid, and fully stirring for 2 hours to obtain the calcium-potassium-containing polyaspartic acid liquid water-soluble fertilizer. The obtained water soluble fertilizer contains polyaspartic acid more than or equal to 12%, calcium more than or equal to 1.0%, and K₂O content is not less than 7.0%, P₂O₅The content is more than or equal to 6.0 percent. The above contents are mass fractions.

The calcium-potassium-containing polyaspartic acid liquid water-soluble fertilizer obtained in the example was subjected to an application test, and the amount of each water-soluble fertilizer used was 5kg/667m compared with the comparative example²The specific data are shown in the following table:

the normal apples are 7 yuan/kg in wholesale price, the fruit of Chinese pistachios is 3 yuan/kg in wholesale price, and compared with the comparative examples 1-4 and 1-6, the example 1 is a 70E for increasing the income of farmers for one year810 Yuan/667 m²(ii) a Compared with comparative examples 1-5, example 1 increased farmer income by 1520 yuan/667 m per year²。

Example 2

A water-soluble fertilizer for preventing and treating apple water core diseases is prepared by adding zinc-containing polyaspartic acid to an existing medium-element water-soluble fertilizer meeting NY2266-2012 or a trace-element water-soluble fertilizer meeting NY1428-2010 or an original formula of a major-element water-soluble fertilizer meeting NY1107-2010, wherein the adding amount is 8.5%, uniformly mixing and stirring to obtain the zinc-containing polyaspartic acid water-soluble fertilizer, and the water-soluble fertilizer is prepared from 8.5kg of zinc-containing polyaspartic acid liquid, 40kg of potassium nitrate, 30kg of potassium dihydrogen phosphate and 100kg of water in a specific ratio, and meets related product standards and related regulations of product types.

The zinc-containing polyaspartic acid is prepared by the following method:

4.5kg of water and 3.0kg of polysuccinimide were added to the reactor in one portion, and the stirring was started. Adding aspartic protease which is activated in water bath at 30 ℃ for 4 hours in advance after the aspartic protease is uniform, controlling the adding time to be 30 +/-5 min and the adding amount to be 50g in the enzyme adding process, controlling the reaction temperature to be 50 +/-5 ℃, starting timing after the temperature reaches the set temperature, and keeping the temperature for 24 hours. And (3) monitoring the molecular weight at any time by Gel Permeation Chromatography (GPC) when the heat preservation period is about to end, quickly and uniformly adding 1.1kg of zinc hydroxide to terminate the reaction when the required molecular weight range is reached, wherein the alkali adding time is generally controlled according to the temperature of a material system, the temperature of the material system needs to be controlled to be less than or equal to 100 ℃, and is as close to the critical temperature of 100 ℃ as possible, and meanwhile, the influence on the efficacy of the polyaspartic acid due to low hydrolysis molecular weight caused by slow alkali addition caused by temperature control is avoided. Adding alkaline substance while regulating pH of the material to obtain zinc-containing polyaspartic acid, and detecting when the temperature of the material is reduced to below 40 deg.C. The detection result shows that the content of the polyaspartic acid is more than or equal to 32 percent, the content of the aspartic acid is less than or equal to 4.0 percent, the weight average molecular weight is 2000D, the distribution rate of the interval is not less than 90 percent, the pH value is 6.5, and the content of the zinc is more than or equal to 8.0 percent. The above contents are mass fractions.

The liquid water-soluble fertilizer containing zinc polyaspartic acid obtained in this example was subjected to an application test, and compared with the comparative example, each waterThe using amount of the dissolved fertilizer is 5kg/667m²Used 3 times per growing season, the specific data are shown in the following table:

normal apples were rated at a wholesale price of 7 yuan/kg, and fruit of water-cored nuts were rated at a wholesale price of 3 yuan/kg. Compared with comparative examples 2-1 to 2-4 and comparative examples 2-6, the yield of the example 2 is increased by 70-450 yuan/667 m for farmers in one year²(ii) a Compared with comparative examples 2-5, example 2 increased the income of farmers 750 yuan/667 m per year²。

Example 3

A water-soluble fertilizer for preventing and treating 'chicken foot disease' of Huangguan pears comprises 50kg of ammonia nitrogen-containing polyaspartic acid, 15.3kg of calcium nitrate tetrahydrate, 10.2kg of potassium nitrate, 4kg of urea and 20.5kg of water, wherein the total weight is 100 kg.

Wherein the polyaspartic acid containing ammonia nitrogen is prepared by the following method:

4.0kg of water and 4.0kg of polysuccinimide were added to the reactor in one portion, and the stirring was started. Adding aspartic protease which is activated in water bath at 30 ℃ for 4 hours in advance after the aspartic protease is uniform, controlling the adding time to be 50 +/-5 min in the enzyme adding process, controlling the adding amount to be 100g, controlling the reaction temperature to be 50 +/-5 ℃, starting timing after the temperature reaches the set temperature, and keeping the temperature for 48 hours. And (3) monitoring the molecular weight at any time by Gel Permeation Chromatography (GPC) when the heat preservation period is about to end, quickly and uniformly adding 1.2kg of ammonia water (the mass concentration of an industrial product is 25-28%) to terminate the reaction when the required molecular weight range is reached, generally controlling the alkali adding time according to the temperature of a material system, controlling the temperature of the material system to be less than or equal to 100 ℃, and approaching the critical temperature of 100 ℃ as much as possible, and simultaneously avoiding the influence on the efficacy of the polyaspartic acid due to low hydrolysis molecular weight caused by slow alkali addition caused by temperature control. Adding an alkaline substance and simultaneously adjusting the pH value of the material to obtain polyaspartic acid containing ammonia nitrogen, carrying out sample sending detection when the temperature of the material is reduced to be lower than 40 ℃, wherein the detection result shows that the content of polyaspartic acid is not less than 40%, the content of aspartic acid is not more than 3.0%, the weight average molecular weight is 1000D, the distribution rate of the interval is not less than 90%, the pH value is 5.8, and the total nitrogen content is not less than 6.0%.

The prepared polyaspartic acid containing ammonia nitrogen is uniformly mixed with other components according to the following scheme: 20.5kg of water and 50kg of ammonia nitrogen-containing polyaspartic acid are added into a container at one time, the heating is started to set the temperature at 45 +/-5 ℃, 15.3kg of calcium nitrate tetrahydrate, 10.2kg of potassium nitrate and 4kg of urea are sequentially added, and after the materials are dissolved and the temperature is stabilized for 5min, the ammonia nitrogen-containing polyaspartic acid liquid water-soluble fertilizer is obtained after all the materials are completely dissolved. The content of polyaspartic acid in the obtained water-soluble fertilizer is more than or equal to 20 percent, the content of total nitrogen is more than or equal to 6.0 percent, and K is₂The contents of O and calcium are respectively greater than or equal to 2.5% and 4.0% by mass.

The application test of the liquid water-soluble fertilizer containing the ammonia nitrogen type polyaspartic acid obtained in the embodiment is carried out, and compared with the comparative example, the application amount of the liquid water-soluble fertilizer is 5kg/667m²The specific data are shown in the following table:

the normal pear fruit is calculated according to the wholesale price of 5 yuan/kg, and the drumstick fruit is calculated according to the wholesale price of 2 yuan/kg. Compared with comparative examples 3-1 to 3-4 and 3-6, example 3 increases the income of farmers by 170-520 yuan/667 m in one year²(ii) a Compared with comparative examples 3-5, example 3 increased the income of farmers 1360 yuan/667 m per year²。

Example 4

A water-soluble fertilizer for preventing and treating 'chicken foot disease' of Huangguan pears is prepared by adding calcium-containing polyaspartic acid to an existing medium-element water-soluble fertilizer meeting NY2266-2012 requirements, or a trace-element water-soluble fertilizer meeting NY1428-2010 requirements, or an original formula of a NY1107-2010 macroelement water-soluble fertilizer, uniformly mixing and stirring to obtain a calcium-containing polyaspartic acid liquid water-soluble fertilizer, wherein the water-soluble fertilizer comprises 15kg of calcium-containing polyaspartic acid liquid, 35kg of potassium nitrate, 35kg of potassium dihydrogen phosphate and 100kg of water in a specific mass ratio, and meets related product standards and related regulations of product types.

The calcium-containing polyaspartic acid is prepared by the following method:

4.5kg of water and 3.0kg of polysuccinimide were added to the reactor in one portion, and the stirring was started. Adding aspartic protease which is activated in water bath at 30 ℃ for 4 hours in advance after the aspartic protease is uniform, controlling the adding time to be 30 +/-5 min and the adding amount to be 50g in the enzyme adding process, controlling the reaction temperature to be 55 +/-5 ℃, starting timing after the temperature reaches the set temperature, and keeping the temperature for 36 hours. And (3) monitoring the molecular weight at any time by Gel Permeation Chromatography (GPC) when the heat preservation period is about to end, quickly and uniformly adding 1.1kg of calcium hydroxide to terminate the reaction when the required molecular weight range is reached, wherein the alkali adding time is generally controlled according to the temperature of a material system, the temperature of the material system needs to be controlled to be less than or equal to 100 ℃, and is as close to the critical temperature of 100 ℃ as possible, and meanwhile, the influence on the efficacy of the polyaspartic acid due to low hydrolysis molecular weight caused by slow alkali addition caused by temperature control is avoided. Adding alkaline substances and adjusting the pH value of the material to obtain calcium-containing polyaspartic acid, and carrying out sample sending detection when the temperature of the material is reduced to be lower than 40 ℃, wherein the detection result shows that the content of the polyaspartic acid is more than or equal to 25%, the content of the aspartic acid is less than or equal to 4.0%, the weight average molecular weight is 1500D, the distribution rate of the interval is not less than 90%, the pH value is 6.0, and the content of calcium is more than or equal to 6.0%.

The calcium-containing polyaspartic acid liquid water-soluble fertilizer obtained in the example was subjected to an application test, and compared with a comparative example, the application amount was 5kg/667m²Used 3 times per growing season, the specific data are shown in the following table:

the normal pear fruit is calculated according to the wholesale price of 5 yuan/kg, and the drumstick fruit is calculated according to the wholesale price of 2 yuan/kg. Compared with comparative examples 4-1 to 4-4 and 4-6, the example 4 increases the income of farmers by 120-640 yuan/667 m in one year²(ii) a Example 4 in comparison with comparative examples 4 to 5Increase the income of farmers in one year 970 yuan/667 m²。

Comparative example

The respective proportional formulas and preparation methods are illustrated in the following tables

The main reasons for the formation and occurrence of physiological diseases of northern deciduous fruit trees are imbalance of C/N ratio in crop nutrition and imbalance of absorption of macroelements/medium trace elements; wherein the imbalance of the C/N ratio comprises the large-scale application of chemical fertilizers and the reduction of organic fertilizers, the large-scale application of the chemical fertilizers causes the activity of soil floras on organic substances to be weakened, the large-scale application of the chemical fertilizers causes the damage of soil structures and the like; imbalances in macroelement/medium trace element absorption include excessive application of macroelement chemical fertilizers and fixation of trace elements in soil, excessive application of macroelement chemical fertilizers and weakening of soil porosity, excessive application of macroelement chemical fertilizers and weakening of absorption of seed trace elements by crops and the like. The research of the invention finds that the polyaspartic acid prepared by an enzymolysis method has various functions of adjusting the reasons: firstly, the polyaspartic acid has concentrated molecular weight, has the characteristic of enzyme, can stimulate the absorption and utilization of medium and trace elements of crops, activates the medium and trace elements in soil and reduces the fixation of the medium and trace elements; secondly, the polyaspartic acid in the molecular weight section has the lasting effect of common polyaspartic acid and the quick-acting effect of common organic fertilizer due to the synergistic and chelating functions, and the improvement on the yield and the quality of crops is more excellent, so that the use proportion of chemical fertilizer can be reduced; finally, the polyaspartic acid is a polymer of amino acid, can be used as a nutrient component, is decomposed by microorganisms, and can also be utilized and decomposed by crops, so that a C source can be better supplied to the crops and soil microorganisms, and the soil structure can be improved.

According to the comparison result, the polyaspartic acid liquid water-soluble fertilizer which can stably and effectively promote nutrient elements to be absorbed in the growth process of deciduous fruit trees is obtained by reasonably controlling the enzymolysis conditions and is used as a main agent or a synergistic auxiliary agent of the water-soluble fertilizer, so that the polyaspartic acid liquid water-soluble fertilizer with the obvious effect of preventing and treating physiological diseases of deciduous fruit trees is obtained.