CN115974624A - High-yield slow-release compound fertilizer for saline-alkali soil and application thereof - Google Patents

Abstract

The invention provides a slow-release compound fertilizer for saline-alkali soil and a preparation method and application thereof, belonging to the technical field of saline-alkali soil improvement fertilizers. The slow release compound fertilizer comprises the following components: biochar, humic acid, urea phosphate, potassium sulfate, a compound microbial agent and a coating material; the coating material comprises polyvinyl alcohol, polyglutamic acid and zeolite powder. The components of the slow-release compound fertilizer have synergistic effect, so that the pH value of the saline-alkali soil is effectively reduced, the nitrogen leaching loss is effectively prevented, the fertilizer efficiency of the compound fertilizer is prolonged, the application amount of the fertilizer is reduced, and the crop yield is improved.

Description

A high-yield slow-release compound fertilizer for saline-alkali land and its application

Technical Field

The invention relates to the technical field of improved fertilizers, and in particular to a slow-release compound fertilizer for saline-alkali land and a preparation method and application thereof.

Background Art

The salt in saline-alkali soil accumulates on the surface, making it difficult for plant roots to absorb water, causing "physiological drought" in plants, severe water loss in plants, and "reverse osmosis" phenomenon, which directly leads to plant withering and death; the salt content in the soil increases, and the concentration of certain ions is too high, which is easy to be toxic to general plants, directly corroding the tender shoots, young roots and some fibrous tissues of plants, causing harm. In addition, when there are too many soluble salts in the soil, the soil fertility will also decrease, and the carbonate and bicarbonate content in saline-alkali soil will increase. After hydrolysis, the acidity and alkalinity of the soil will show strong alkalinity as the pH value of the soil increases. The solubility of macroelements and trace elements in the soil will decrease significantly as the alkalinity increases, resulting in a decrease in the effectiveness of soil nutrients, inhibiting the absorption and utilization of soil nutrients by plants, and reducing yields. Moreover, when the soil nutrients decrease, the application of compound fertilizers can increase yields in a short period of time, but it can also lead to a reduction in crop yields in a long period of time. It can be seen that the improvement and utilization of saline-alkali resources is crucial to agricultural development and ecological protection.

At present, the methods for improving saline-alkali land mainly include physical methods, chemical methods and biological methods. Among them, physical methods generally use irrigation and drainage systems, flushing and desalination, loosening and pressing, etc. to achieve the purpose of improvement and utilization, but due to high costs, low outputs, or secondary pollution, or resource limitations, they cannot be truly promoted in production; although chemical methods can improve the yield of crops in saline-alkali land in a short period of time, they are also prone to aggravate other forms of pollution in improved saline-alkali land. For example, for soda saline-alkali soil, the introduction of _SO2 can reduce the soil pH value, but the more soluble _Na2SO4 produced will aggravate the salt stress on the plant _roots ; traditional biological methods mainly plant salt-alkali tolerant plants and fertilize the soil. This method has a long cycle and high cost, and it is difficult to quickly and efficiently improve large-scale saline-alkali soil and increase crop yields.

Compound fertilizers mainly contain three elements: nitrogen, phosphorus, and potassium. They can replenish nutrients lost, thereby increasing the total yield of crops. However, the utilization rate of compound fertilizers in saline-alkali land has a downward trend, and the yield of crops is much lower than before. Many agricultural studies have pointed out that although compound fertilizers can supplement sufficient nutrients for the soil, the loss of nutrients in saline-alkali land is serious, and more compound fertilizers need to be applied multiple times to ensure the high yield of crops. However, the increase in the amount of compound fertilizers will have adverse effects on the soil and the environment. Therefore, it is urgent to invent a slow-release fertilizer that can be used in saline-alkali land, which can not only prolong the fertilizer effect, but also improve the soil environment and increase crop yields.

Summary of the invention

The purpose of the present invention is to provide a high-yield slow-release compound fertilizer for saline-alkali land and a preparation method and application thereof. The slow-release compound fertilizer provided by the present invention can not only improve the soil environment of saline-alkali land, but also achieve a slow-release and long-term effect, thereby achieving a high-yield effect.

In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

The invention provides a high-yield slow-release compound fertilizer for saline-alkali land, comprising the following raw materials in parts by weight: 20-30 parts of biochar, 3-8 parts of humic acid, 25-35 parts of urea, 18-23 parts of urea phosphate, 7-13 parts of potassium sulfate, 0.3-0.9 parts of composite microbial agent and 31.5-46.5 parts of coating material; the coating material comprises polyvinyl alcohol, polyglutamic acid and zeolite powder; the mass ratio of the polyvinyl alcohol, polyglutamic acid and zeolite powder is (0.3-1.5):(1-5):(20-30).

Preferably, the composite microbial agent includes Bacillus subtilis ZLS-01 agent, Aspergillus niger NJDL-12 agent and Trichoderma ST02 agent, and the mass ratio of the Bacillus subtilis ZLS-01 agent, Aspergillus niger NJDL-12 agent and Trichoderma ST02 agent is (1-3):(1-3):(1-3).

The present invention also provides a preparation method of the above-mentioned slow-release compound fertilizer, comprising the following steps: mixing the polyvinyl alcohol with water to obtain a polyvinyl alcohol solution, mixing it with polyglutamic acid and imidic acid ester solution to obtain a reaction system, performing cross-linking modification, and after the reaction is completed, mixing it with the urea and zeolite powder, sieving to obtain coated urea; mixing the coated urea with the biochar, humic acid, urea phosphate, potassium sulfate and composite microbial agent to obtain a slow-release compound fertilizer.

Preferably, the mass percentage of the polyvinyl alcohol solution is 3%-8%.

Preferably, the volume percentage of the imidic acid ester solution is preferably 20%-30%; the addition amount of the imidic acid ester solution is 0.1%-0.5% of the volume of the reaction system.

Preferably, the cross-linking modification temperature is 55-65° C. and the time is 1.5-2.5 h.

The present invention also provides application of the above slow-release compound fertilizer in increasing crop yield.

Preferably, the crop comprises corn.

Preferably, the slow-release compound fertilizer is applied as a base.

Preferably, the application amount of the slow-release compound fertilizer is 30-40 kg/mu.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention provides a high-yield slow-release compound fertilizer for saline-alkali land, comprising: biochar, humic acid, urea, urea phosphate, potassium sulfate, composite microbial agent and coating material; the coating material comprises polyvinyl alcohol, polyglutamic acid and zeolite powder. Among them, biochar can make the soil more loose, improve the compaction condition of saline-alkali land, and at the same time improve the ability of soil to absorb organic matter and fertilizer, can increase the organic matter content of soil, delay the release of fertilizer, and play the role of fertilization and slow release; the humic acid has a variety of active groups, which can improve the buffering capacity of soil to alkalinity changes; after coating, urea can reduce nitrogen leaching during crop planting; the urea phosphate itself is acidic, which will be able to reduce the pH value of saline-alkali soil, play the role of improving soil structure, promoting crop growth, etc.; the composite microbial agent increases the diversity of microorganisms in the soil, has the effect of enhancing soil microbial activity, improving soil physical and chemical properties, and improving soil fertility. The components of the slow-release compound fertilizer of the present invention have synergistic effects, effectively reduce the pH value of saline-alkali soil, effectively prevent nitrogen leaching, extend the fertilizer effect of the compound fertilizer, reduce the amount of fertilizer applied, and increase the yield of crops.

DETAILED DESCRIPTION

The invention provides a high-yield slow-release compound fertilizer for saline-alkali land, comprising the following raw materials in parts by weight: 20-30 parts of biochar, 3-8 parts of humic acid, 25-35 parts of urea, 18-23 parts of urea phosphate, 7-13 parts of potassium sulfate, 0.3-0.9 parts of composite microbial agent and 31.5-46.5 parts of coating material; the coating material comprises polyvinyl alcohol, polyglutamic acid and zeolite powder; the mass ratio of the polyvinyl alcohol, polyglutamic acid and zeolite powder is (0.3-1.5):(1-5):(20-30).

The gaps between the internal molecules of the biochar of the present invention are relatively large, and it has good water absorption capacity, which can make the soil more loose, improve the compaction condition of saline-alkali land, and improve the ability of soil to absorb organic matter and fertilizer, so it can increase the organic matter content of the soil, delay the release of fertilizer, and play the role of fertilization and slow release; the humic acid has a variety of active groups, has strong hydrophilicity, cation exchange, complexing ability and high adsorption capacity, etc., which can improve the buffering capacity of soil to alkalinity changes; after the urea is coated, it can reduce nitrogen leaching during crop planting; the urea phosphate itself is acidic, which will be able to reduce the pH value of saline-alkali soil to a limited extent, thereby improving soil physical and chemical properties, improving soil structure, and promoting crop growth; the composite microbial agent increases the diversity of microorganisms in the soil, has the effect of enhancing soil microbial activity, improving soil physical and chemical properties, and improving soil fertility. The components of the slow-release compound fertilizer of the present invention have a synergistic effect, effectively reduce the pH value of saline-alkali soil, effectively prevent nitrogen leaching, extend the fertilizer effect of compound fertilizer, reduce the amount of fertilizer applied, and increase crop yield.

In the present invention, the composite microbial agent preferably includes Bacillus subtilis ZLS-01 agent, Aspergillus niger NJDL-12 agent and Trichoderma ST02 agent; the effective live bacteria amount in the composite microbial agent is ≥10 ⁸ cfu/mL; the mass ratio of the Bacillus subtilis ZLS-01 agent, Aspergillus niger NJDL-12 agent and Trichoderma ST02 agent is preferably (1-3):(1-3):(1-3), more preferably 2:2:2. The Bacillus subtilis ZLS-01 of the present invention has a deposit number of CGMCC No. 3513, which was deposited in the General Microbiological Center of China National Microbiological Culture Collection Committee (hereinafter referred to as CGMCC, address: Datun Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, zip code 100101) on December 17, 2009, and the deposit number is CGMCC No. 3513; the Aspergillus niger NJDL-12 has a deposit number of CGMCC NO. 11544, which was deposited in the General Microbiological Center of China National Microbiological Culture Collection Committee on October 26, 2015, and the deposit address is: No. 3, No. 1, Beichen West Road, Chaoyang District, Beijing; the Trichoderma ST02 is Trichoderma harzianum ST02, with a deposit number of CGMCC No.16964, deposited in the General Microbiological Center of China Microbiological Culture Collection Administration on December 5, 2018. The present invention has no special limitation on the preparation of the composite bacterial agent, and conventional preparation methods in the art can be used.

The strains of the composite bacterial agent of the present invention have no antagonism between each other, and the functions of each microorganism are relatively stable. They can play different roles in the slow-release compound fertilizer, increase the microbial diversity in the soil, enhance the activity of soil microorganisms, improve the physical and chemical properties of the soil, and improve the soil fertility.

The present invention also provides a preparation method of the above-mentioned slow-release compound fertilizer, comprising the following steps: mixing the polyvinyl alcohol with water to obtain a polyvinyl alcohol solution, mixing it with polyglutamic acid and imidic acid ester solution to obtain a reaction system, performing cross-linking modification, and after the reaction is completed, mixing it with the urea and zeolite powder, sieving to obtain coated urea; mixing the coated urea with the biochar, humic acid, urea phosphate, potassium sulfate and composite microbial agent to obtain a slow-release compound fertilizer.

The mixing temperature of the polyvinyl alcohol and water of the present invention is preferably 85-93°C, more preferably 90°C, and the mixing time is preferably 45-90min, more preferably 60min; the imidic acid ester solution acts as a cross-linking agent; the polyvinyl alcohol and polyglutamic acid undergo a cross-linking reaction to prepare a coating material with strong adhesion and good water resistance. After mixing with urea and zeolite powder, the obtained coated urea has the ability to slowly release nitrogen.

In the present invention, the mass percentage of the polyvinyl alcohol solution is preferably 3%-8%, more preferably 5%; the volume percentage of the imidic acid ester solution is preferably 20%-30%, more preferably 25%; the addition amount of the imidic acid ester solution is preferably 0.1%-0.5% of the volume of the reaction system, more preferably 0.3%; the temperature of the cross-linking modification is preferably 55-65°C, more preferably 60°C, and the time is preferably 1.5-2.5h, more preferably 2h.

The present invention also provides application of the above slow-release compound fertilizer in increasing crop yield.

In the present invention, the crops preferably include corn; the slow-release compound fertilizer is preferably applied as a base fertilizer; the application amount of the slow-release compound fertilizer is preferably 30-40 kg/mu, more preferably 35 kg/mu.

In the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example 1

Preparation of compound bacterial agent

Bacillus subtilis ZLS-01, Aspergillus niger NJDL-12 and Trichoderma ST02 are respectively activated by seeds, cultured by seeds, fermented, concentrated and dried to obtain corresponding microbial agents, which are then mixed in equal weight to obtain the composite microbial agent. The effective live bacterial amount in the composite microbial agent is ≥10 ⁸ cfu/mL.

Example 2

Preparation of high-yield slow-release compound fertilizer for saline-alkali land

(1) 1 kg of polyvinyl alcohol was mixed with 19 kg of water at 90° C. for 60 min to obtain a polyvinyl alcohol solution, which was mixed with 3 kg of polyglutamic acid and 69 g of an imidic acid ester solution having a volume percentage of 25% to obtain a reaction system, and cross-linked at 60° C. for 2 h. After the reaction was completed, a coating solution was obtained;

(2) Spraying the coating solution on the surface of 30 kg of urea, then coating it with 25 kg of zeolite powder, and drying it to obtain coated urea;

(3) The coated urea was mixed evenly with 25 kg of biochar, 5 kg of humic acid, 20 kg of urea phosphate, 10 kg of potassium sulfate, and 0.5 kg of the composite microbial agent obtained in Example 1 to obtain a slow-release composite fertilizer.

Example 3

Preparation of high-yield slow-release compound fertilizer for saline-alkali land

(1) 0.3 kg of polyvinyl alcohol was mixed with 9.7 kg of water at 85° C. for 93 min to obtain a polyvinyl alcohol solution, which was mixed with 1 kg of polyglutamic acid and 11 mL of an imidic acid ester solution having a volume percentage of 20% to obtain a reaction system, and cross-linked at 55° C. for 2.5 h. After the reaction was completed, a coating solution was obtained;

(2) Spraying the coating solution on the surface of 25 kg of urea, then coating it with 20 kg of zeolite powder, and drying it to obtain coated urea;

(3) The coated urea was mixed evenly with 20 kg of biochar, 3 kg of humic acid, 18 kg of urea phosphate, 7 kg of potassium sulfate, and 0.3 kg of the composite microbial agent obtained in Example 1 to obtain a slow-release composite fertilizer.

Example 4

Preparation of high-yield slow-release compound fertilizer for saline-alkali land

(1) 1.5 kg of polyvinyl alcohol was mixed with 18.5 kg of water at 93° C. for 45 min to obtain a polyvinyl alcohol solution, which was then mixed with 5 kg of polyglutamic acid and 125 mL of an imidic acid solution having a volume percentage of 30% to obtain a reaction system, and cross-linked at 65° C. for 1.5 h. After the reaction was completed, a coating solution was obtained;

(2) Spraying the coating solution on the surface of 35 kg of urea, then coating it with 20 kg of zeolite powder, and drying it to obtain coated urea;

(3) The coated urea was mixed evenly with 30 kg of biochar, 8 kg of humic acid, 23 kg of urea phosphate, 13 kg of potassium sulfate, and 0.9 kg of the composite microbial agent obtained in Example 1 to obtain a slow-release compound fertilizer.

Comparative Example 1

The specific implementation is the same as that of Example 2, except that there are no steps (1) and (2).

Comparative Example 2

The specific implementation is the same as Example 2, except that no biochar is added.

Comparative Example 3

The specific implementation is the same as that of Example 2, except that no composite microbial agent is added.

Experimental Example 1

Experiment on nitrogen release of slow-release compound fertilizer

Field nitrogen release experiment

The fertilizers prepared in Examples 2-4 and Comparative Examples 1-3 were respectively placed in double-layer nylon mesh bags and buried in a 15 cm deep soil layer (Inner Mongolia saline-alkali soil) during the corn planting period. Samples were collected for determination at 7, 14, 30, 60, 90, and 120 days after sowing, and each sampling was repeated 3 times. There was no significant difference in the situation of each repeated soil. The determination of nitrogen was carried out by concentrated sulfuric acid digestion-Kjeldahl method, and the nitrogen release rate was calculated. Nitrogen release rate (%) = nitrogen release amount/fertilizer sample weight × 100. The specific results are shown in Table 1.

Table 1 Nitrogen release rate of different fertilizers in some fields (%)

deal with 7 days 14 days 30 days 60 days 90 days 120 days Example 2 18.7 34.5 42.5 55.9 75.8 83.3 Example 3 20.3 36.2 44.7 58.7 79.7 85.7 Example 4 19.5 37.9 43.7 58.4 80.2 87.5 Comparative Example 1 38.8 50.8 73.7 85.8 89.7 96.3 Comparative Example 2 35.6 48.2 62.6 79.5 85.5 95.9 Comparative Example 3 36.8 45.4 61.3 77.9 84.9 95.2

From the data in Table 1, it can be seen that the slow-release period (the time when the cumulative release rate reaches 80%) of the fertilizers in Examples 1-3 of the present invention is about 120 days, which is consistent with the nitrogen demand during the growth of corn. Compared with the fertilizers in Comparative Examples 1-3, the fertilizers of the present invention have a synergistic effect and can achieve a significant slow-release effect.

Experimental Example 2

Field experiment of slow-release compound fertilizer

Experimental location: Tuoketuo County, Hohhot City, Inner Mongolia, Tuoketuo Scientific Research Base of Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences;

Corn variety: Jingke 968;

Experimental setup: Examples 2-4 and Comparative Examples 1-3 were used for 6 fertilizer application treatments, with each fertilizer application rate of 35 kg/mu; no fertilizer application was used as the control, with a total of 7 treatments; the corn planting area of each treatment was 30 m ² ; each treatment was repeated 3 times, and there was no significant difference in the soil conditions of each repeat. The soil pH value before and after planting was measured by potentiometric determination, and the soil pH value before planting was 8.6.

Fertilizer should be applied once as base fertilizer before tilling the soil, plowed deep into the soil, with a fertilization depth of 25cm, and covered with soil.

After the corn matured, the yield was counted. The specific results are shown in Table 2.

Table 2 Yield and soil pH of different fertilizers

It can be seen from the data in Table 2 that the slow-release compound fertilizer of the present invention can not only reduce the pH value of saline-alkali soil and improve the compaction of the soil, but also significantly increase the yield of corn compared with the control.

The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims (10)

1. A high-yield slow-release compound fertilizer for saline-alkali land, characterized by comprising the following raw materials in parts by weight: 20-30 parts of biochar, 3-8 parts of humic acid, 25-35 parts of urea, 18-23 parts of urea phosphate, 7-13 parts of potassium sulfate, 0.3-0.9 parts of composite microbial agent and 31.5-46.5 parts of coating material; The coating material comprises polyvinyl alcohol, polyglutamic acid and zeolite powder; the mass ratio of the polyvinyl alcohol, polyglutamic acid and zeolite powder is (0.3-1.5):(1-5):(20-30). 2. slow-release composite fertilizer according to claim 1, is characterized in that, described composite microbial inoculant comprises bacillus subtilis ZLS-01 inoculant, aspergillus niger NJDL-12 inoculant and Trichoderma ST02 inoculant, and the mass ratio of described bacillus subtilis ZLS-01 inoculant, aspergillus niger NJDL-12 inoculant and Trichoderma ST02 inoculant is (1-3):(1-3):(1-3). 3. The method for preparing the slow-release compound fertilizer according to claim 1 or 2, characterized in that it comprises the following steps: mixing the polyvinyl alcohol with water to obtain a polyvinyl alcohol solution, mixing it with polyglutamic acid and imidic acid ester solution to obtain a reaction system, performing cross-linking modification, and after the reaction is completed, mixing it with the urea and zeolite powder, sieving to obtain coated urea; mixing the coated urea with the biochar, humic acid, urea phosphate, potassium sulfate and composite microbial agent to obtain a slow-release compound fertilizer. 4. The preparation method according to claim 3, characterized in that the mass percentage of the polyvinyl alcohol solution is 3%-8%. 5. The preparation method according to claim 3, characterized in that the volume percentage of the imidic acid ester solution is 20%-30%; the addition amount of the imidic acid ester solution is 0.1%-0.5% of the volume of the reaction system. 6. The preparation method according to claim 3, characterized in that the temperature of the cross-linking modification is 55-65°C and the time is 1.5-2.5h. 7. Use of the slow-release compound fertilizer according to claim 1 or 2 in increasing crop yield. 8. The use according to claim 7, characterized in that the crop comprises corn. 9. The use according to claim 7, characterized in that the slow-release compound fertilizer is applied as a base. 10. The use according to claim 9, characterized in that the application amount of the slow-release compound fertilizer is 30-40 kg/mu.